"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
If a prototype is ever built, attention to the type and quality of the capacitors used will be needed.
Electrolytics are not intended. Put C1 and C2 near U1 supply pins.
If electrolytics are not intended, why are most of the capacitors rated at 10V?
Yes
When I cut and pasted the file the capacitors were mostly labelled as 10?, 1? and - in the case of the wein bridge capacitors
0.015?
When I cut and pasted the file into notepad++ and removed line 391 and subsequent lines (or fixed wraps) and under encoding
converted to ANSI everything worked fine.
The 15nF capacitors are rated at 16V - the polypropylene parts you can actually buy that are offered with a +/-1% tolerance are
63V and 250V parts
You'd have to take that up with the LTSpice parts library.
I presume you intended u or the Greek mu symbol, and after I'd done that substitution the simulation did work, if not well.
No substitution is required if you convert to ANSI in notepad++
The feedback loop doesn't settle well, and I suspect that I know why. R4 should probably be in series with C3, not in parallel.
More later.
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
If a prototype is ever built, attention to the type and quality of the capacitors used will be needed.
Electrolytics are not intended. Put C1 and C2 near U1 supply pins.
If electrolytics are not intended, why are most of the capacitors rated
at 10V?
When I cut and pasted the file the capacitors were mostly labelled as
10?, 1? and - in the case of the wein bridge capacitors 0.015?
The 15nF capacitors are rated at 16V - the polypropylene parts you can >actually buy that are offered with a +/-1% tolerance are 63V and 250V parts
I presume you intended u or the Greek mu symbol, and after I'd done that >substitution the simulation did work, if not well.
The feedback loop doesn't settle well, and I suspect that I know why. R4 >should probably be in series with C3, not in parallel. More later.
--
Bill Sloman, Sydney
On 9/11/2024 7:39 pm, Edward Rawde wrote:...
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
If a prototype is ever built, attention to the type and quality of the capacitors used will be needed.
Electrolytics are not intended. Put C1 and C2 near U1 supply pins.
In fact I also had to take out C6 and R9. Once I'd done that the circuit simulated a lot faster, and settled down after about 20
seconds. The next 20 seconds showed a third harmonic spike about 60DB below the fundamental - respectable but not great. Putting
too much delay into a feedback loop makes it unstable - that's what Bode plots are all about.
--
Bill Sloman, Sydney
--
Bill Sloman, Sydney
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers.
This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
There are two things I don't understand about my own circuit.
1. Why does LT1678 work fine in position U2 but LT1057 does not.
2. Why is the DC stabilization circuit (U3 and associated components) needed and would it work just the same in reality?
Version 4
SHEET 1 2196 932
WIRE -64 -576 -96 -576
WIRE 48 -576 16 -576
WIRE 128 -528 112 -528
WIRE 208 -528 192 -528
WIRE 288 -528 272 -528
WIRE 368 -528 352 -528
WIRE 448 -528 432 -528
WIRE 528 -528 512 -528
WIRE 640 -528 592 -528
WIRE 640 -512 640 -528
WIRE -32 -464 -32 -480
WIRE 48 -448 48 -576
WIRE 48 -448 0 -448
WIRE -96 -432 -96 -576
WIRE -64 -432 -96 -432
WIRE 112 -416 112 -528
WIRE 112 -416 0 -416
WIRE 160 -416 112 -416
WIRE 208 -416 160 -416
WIRE 336 -416 288 -416
WIRE 400 -416 336 -416
WIRE 512 -416 400 -416
WIRE 624 -416 512 -416
WIRE -96 -384 -96 -432
WIRE -32 -384 -32 -400
WIRE 48 -368 48 -448
WIRE 336 -368 336 -416
WIRE 160 -352 160 -416
WIRE 400 -352 400 -416
WIRE 512 -288 512 -416
WIRE 624 -288 624 -416
WIRE -96 -272 -96 -304
WIRE -96 -272 -192 -272
WIRE -96 -240 -96 -272
WIRE 48 -240 48 -288
WIRE 160 -240 160 -288
WIRE 336 -240 336 -288
WIRE 400 -240 400 -288
WIRE -192 -176 -192 -272
WIRE -224 -128 -256 -128
WIRE -96 -128 -96 -160
WIRE -96 -128 -128 -128
WIRE -80 -128 -96 -128
WIRE 144 -128 -80 -128
WIRE 288 -128 224 -128
WIRE 352 -128 288 -128
WIRE 512 -128 512 -224
WIRE 512 -128 432 -128
WIRE -256 -48 -256 -128
WIRE -208 -48 -256 -48
WIRE -80 -48 -80 -128
WIRE -80 -48 -128 -48
WIRE 288 -16 288 -128
WIRE 288 -16 64 -16
WIRE 352 -16 288 -16
WIRE 512 -16 512 -128
WIRE 512 -16 432 -16
WIRE -256 0 -256 -48
WIRE 144 48 144 32
WIRE -240 96 -320 96
WIRE -176 96 -240 96
WIRE 64 96 64 -16
WIRE 112 96 64 96
WIRE 512 96 512 -16
WIRE 512 96 272 96
WIRE -32 128 -96 128
WIRE 112 128 -32 128
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WIRE 624 144 624 -224
WIRE 656 144 624 144
WIRE 752 144 720 144
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WIRE -32 160 -32 128
WIRE 112 160 64 160
WIRE 624 160 624 144
WIRE 624 160 272 160
WIRE 752 176 752 144
WIRE 144 224 144 208
WIRE -32 256 -32 224
WIRE 64 272 64 160
WIRE 160 272 64 272
WIRE 288 272 160 272
WIRE 400 272 352 272
WIRE 512 272 512 96
WIRE 512 272 480 272
WIRE 64 288 64 272
WIRE 160 288 160 272
WIRE 752 288 752 256
WIRE 880 288 752 288
WIRE 928 288 880 288
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WIRE -320 320 -400 320
WIRE 928 320 928 288
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WIRE -176 336 -320 336
WIRE -96 336 -96 128
WIRE 64 384 64 368
WIRE 160 384 160 352
WIRE 160 384 64 384
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WIRE 64 416 64 384
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WIRE 304 432 272 432
WIRE 384 432 368 432
WIRE 928 432 928 400
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WIRE 624 448 624 160
WIRE 288 544 288 528
WIRE 384 560 384 432
WIRE 384 560 320 560
WIRE 624 560 624 512
WIRE 624 560 384 560
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WIRE 32 576 -48 576
WIRE 144 576 144 432
WIRE 144 576 112 576
WIRE 208 576 144 576
WIRE 256 576 208 576
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WIRE -240 592 -320 592
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WIRE -176 592 -240 592
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WIRE 512 592 512 512
WIRE 512 592 432 592
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WIRE 624 640 624 592
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WIRE -48 736 -48 688
WIRE -48 736 -96 736
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WIRE 512 736 512 704
WIRE 512 736 432 736
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WIRE 624 736 512 736
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FLAG -400 336 0
FLAG 288 528 V+
FLAG 144 224 V-
FLAG -240 96 V+
FLAG -240 592 V-
FLAG 880 288 output
FLAG 144 32 V+
FLAG 288 624 V-
FLAG 432 768 0
FLAG -32 256 0
FLAG -32 -480 V+
FLAG -32 -384 V-
FLAG -256 0 0
FLAG 400 -240 0
FLAG 160 -240 0
FLAG 64 416 0
FLAG 336 -240 0
FLAG -96 768 0
FLAG 208 576 dc-trim
FLAG 640 -512 0
FLAG 48 -240 0
FLAG 928 432 0
SYMBOL voltage -320 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 12 7 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
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SYMATTR Value 6
SYMBOL res 496 256 R90
WINDOW 0 1 52 VBottom 2
WINDOW 3 33 45 VTop 2
SYMATTR InstName R11
SYMATTR Value 10.5k
SYMBOL cap 352 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 35 30 VTop 2
SYMATTR InstName C8
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL res 240 -144 R90
WINDOW 0 -1 46 VBottom 2
WINDOW 3 35 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 6.34k
SYMBOL res 448 -144 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R8
SYMATTR Value 13k
SYMBOL njf -128 -176 R90
WINDOW 0 -37 23 VRight 2
WINDOW 3 -9 -3 VRight 2
SYMATTR InstName J1
SYMATTR Value J112
SYMBOL voltage -320 400 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 10 0 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V2
SYMATTR Value 6
SYMBOL res 48 272 R0
WINDOW 3 36 65 Left 2
SYMATTR Value 10.5k
SYMATTR InstName R10
SYMBOL schottky 496 -288 R0
WINDOW 3 -17 -26 VRight 2
SYMATTR Value BAS40HY
SYMATTR InstName D1
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -112 -64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 82
SYMBOL OpAmps\\LT1994 176 128 R0
WINDOW 3 10 -65 Left 2
WINDOW 0 11 -95 Left 2
SYMATTR InstName U1
SYMBOL OpAmps\\LT1057 288 512 M0
WINDOW 0 19 104 Left 2
WINDOW 3 18 130 Left 2
SYMATTR InstName U3
SYMBOL schottky 528 448 M0
WINDOW 3 52 -26 VRight 2
WINDOW 0 -18 3 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 640 448 M0
WINDOW 3 49 -26 VRight 2
WINDOW 0 -21 4 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D4
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 528 608 M0
WINDOW 3 25 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R16
SYMBOL res 720 608 M0
WINDOW 3 27 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R17
SYMBOL res -112 -256 R0
WINDOW 0 38 42 Left 2
WINDOW 3 36 66 Left 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 320 -384 R0
WINDOW 0 -50 69 Left 2
WINDOW 3 -54 98 Left 2
SYMATTR InstName R13
SYMATTR Value 220k
SYMBOL res 448 -32 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R9
SYMATTR Value 1.0469Meg
SYMBOL res -80 -288 R180
WINDOW 0 40 70 Left 2
WINDOW 3 45 42 Left 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res -80 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
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SYMATTR Value 33k
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 220
SYMBOL res 16 560 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL cap 176 352 R180
WINDOW 0 -37 41 Left 2
WINDOW 3 -50 13 Left 2
SYMATTR InstName C7
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL cap 720 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 100000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.002 Lser=0 mfg="TDK" pn="C575OX5ROJI07M" type="X5R"
SYMBOL res 736 160 R0
SYMATTR InstName R18
SYMATTR Value 600
SYMBOL res 192 -400 R270
WINDOW 0 35 55 VTop 2
WINDOW 3 -6 55 VBottom 2
SYMATTR InstName R12
SYMATTR Value 220k
SYMBOL cap 176 -352 M0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 48 Left 2
SYMATTR InstName C6
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 -352 M0
WINDOW 0 -32 51 Left 2
WINDOW 3 -72 7 Left 2
SYMATTR InstName C10
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 368 448 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C9
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 640 R0
WINDOW 0 -37 6 Left 2
WINDOW 3 -77 53 Left 2
SYMATTR InstName C11
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 608 640 R0
WINDOW 0 -33 9 Left 2
WINDOW 3 -72 51 Left 2
SYMATTR InstName C12
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 160 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -79 48 Left 2
SYMATTR InstName C1
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 432 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 50 Left 2
SYMATTR InstName C2
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -16 224 R180
WINDOW 0 23 78 Left 2
WINDOW 3 -74 78 Left 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL diode -80 688 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL cap -64 688 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C5
SYMATTR Value 1000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM032R60J105ME05" type="X5R"
SYMBOL OpAmps\\LT1678 -32 -432 M0
WINDOW 0 -47 50 Left 2
WINDOW 3 -47 89 Left 2
SYMATTR InstName U2
SYMBOL diode 192 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D6
SYMATTR Value 1N914
SYMBOL diode 272 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D7
SYMATTR Value 1N914
SYMBOL diode 352 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D8
SYMATTR Value 1N914
SYMBOL diode 432 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D9
SYMATTR Value 1N914
SYMBOL diode 512 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D10
SYMATTR Value 1N914
SYMBOL schottky 608 -288 R0
SYMATTR Value BAS40HY
SYMATTR InstName D2
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -80 -560 R270
WINDOW 0 33 55 VTop 2
WINDOW 3 -3 55 VBottom 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 32 -384 R0
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL diode 592 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D11
SYMATTR Value 1N914
SYMBOL res 912 304 R0
SYMATTR InstName R19
SYMATTR Value 600
TEXT -624 272 Left 2 !.tran 0 150s 0s startup
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers.
This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
even if the sim is left to run its
full course. Also, what's the purpose of the 6 diodes in series at the
top of the schematic? If you need to drop 4V there ought to be a more
elegant way of doing it!
There are two things I don't understand about my own circuit.
1. Why does LT1678 work fine in position U2 but LT1057 does not.
2. Why is the DC stabilization circuit (U3 and associated components) needed and would it work just the same in reality?
Version 4
SHEET 1 2196 932
WIRE -64 -576 -96 -576
WIRE 48 -576 16 -576
WIRE 128 -528 112 -528
WIRE 208 -528 192 -528
WIRE 288 -528 272 -528
WIRE 368 -528 352 -528
WIRE 448 -528 432 -528
WIRE 528 -528 512 -528
WIRE 640 -528 592 -528
WIRE 640 -512 640 -528
WIRE -32 -464 -32 -480
WIRE 48 -448 48 -576
WIRE 48 -448 0 -448
WIRE -96 -432 -96 -576
WIRE -64 -432 -96 -432
WIRE 112 -416 112 -528
WIRE 112 -416 0 -416
WIRE 160 -416 112 -416
WIRE 208 -416 160 -416
WIRE 336 -416 288 -416
WIRE 400 -416 336 -416
WIRE 512 -416 400 -416
WIRE 624 -416 512 -416
WIRE -96 -384 -96 -432
WIRE -32 -384 -32 -400
WIRE 48 -368 48 -448
WIRE 336 -368 336 -416
WIRE 160 -352 160 -416
WIRE 400 -352 400 -416
WIRE 512 -288 512 -416
WIRE 624 -288 624 -416
WIRE -96 -272 -96 -304
WIRE -96 -272 -192 -272
WIRE -96 -240 -96 -272
WIRE 48 -240 48 -288
WIRE 160 -240 160 -288
WIRE 336 -240 336 -288
WIRE 400 -240 400 -288
WIRE -192 -176 -192 -272
WIRE -224 -128 -256 -128
WIRE -96 -128 -96 -160
WIRE -96 -128 -128 -128
WIRE -80 -128 -96 -128
WIRE 144 -128 -80 -128
WIRE 288 -128 224 -128
WIRE 352 -128 288 -128
WIRE 512 -128 512 -224
WIRE 512 -128 432 -128
WIRE -256 -48 -256 -128
WIRE -208 -48 -256 -48
WIRE -80 -48 -80 -128
WIRE -80 -48 -128 -48
WIRE 288 -16 288 -128
WIRE 288 -16 64 -16
WIRE 352 -16 288 -16
WIRE 512 -16 512 -128
WIRE 512 -16 432 -16
WIRE -256 0 -256 -48
WIRE 144 48 144 32
WIRE -240 96 -320 96
WIRE -176 96 -240 96
WIRE 64 96 64 -16
WIRE 112 96 64 96
WIRE 512 96 512 -16
WIRE 512 96 272 96
WIRE -32 128 -96 128
WIRE 112 128 -32 128
WIRE -320 144 -320 96
WIRE 624 144 624 -224
WIRE 656 144 624 144
WIRE 752 144 720 144
WIRE -176 160 -176 96
WIRE -32 160 -32 128
WIRE 112 160 64 160
WIRE 624 160 624 144
WIRE 624 160 272 160
WIRE 752 176 752 144
WIRE 144 224 144 208
WIRE -32 256 -32 224
WIRE 64 272 64 160
WIRE 160 272 64 272
WIRE 288 272 160 272
WIRE 400 272 352 272
WIRE 512 272 512 96
WIRE 512 272 480 272
WIRE 64 288 64 272
WIRE 160 288 160 272
WIRE 752 288 752 256
WIRE 880 288 752 288
WIRE 928 288 880 288
WIRE -320 320 -320 224
WIRE -320 320 -400 320
WIRE 928 320 928 288
WIRE -400 336 -400 320
WIRE -320 336 -320 320
WIRE -176 336 -176 224
WIRE -176 336 -320 336
WIRE -96 336 -96 128
WIRE 64 384 64 368
WIRE 160 384 160 352
WIRE 160 384 64 384
WIRE -320 416 -320 336
WIRE 64 416 64 384
WIRE -176 432 -176 336
WIRE 192 432 144 432
WIRE 304 432 272 432
WIRE 384 432 368 432
WIRE 928 432 928 400
WIRE 512 448 512 272
WIRE 624 448 624 160
WIRE 288 544 288 528
WIRE 384 560 384 432
WIRE 384 560 320 560
WIRE 624 560 624 512
WIRE 624 560 384 560
WIRE -96 576 -96 416
WIRE -48 576 -96 576
WIRE 32 576 -48 576
WIRE 144 576 144 432
WIRE 144 576 112 576
WIRE 208 576 144 576
WIRE 256 576 208 576
WIRE -320 592 -320 496
WIRE -240 592 -320 592
WIRE -176 592 -176 496
WIRE -176 592 -240 592
WIRE 432 592 320 592
WIRE 512 592 512 512
WIRE 512 592 432 592
WIRE 624 592 624 560
WIRE 704 592 624 592
WIRE -96 624 -96 576
WIRE -48 624 -48 576
WIRE 288 624 288 608
WIRE 512 624 512 592
WIRE 704 624 704 592
WIRE 432 640 432 592
WIRE 624 640 624 592
WIRE -96 736 -96 688
WIRE -48 736 -48 688
WIRE -48 736 -96 736
WIRE 432 736 432 704
WIRE 512 736 512 704
WIRE 512 736 432 736
WIRE 624 736 624 704
WIRE 624 736 512 736
WIRE 704 736 704 704
WIRE 704 736 624 736
WIRE -96 768 -96 736
WIRE 432 768 432 736
FLAG -400 336 0
FLAG 288 528 V+
FLAG 144 224 V-
FLAG -240 96 V+
FLAG -240 592 V-
FLAG 880 288 output
FLAG 144 32 V+
FLAG 288 624 V-
FLAG 432 768 0
FLAG -32 256 0
FLAG -32 -480 V+
FLAG -32 -384 V-
FLAG -256 0 0
FLAG 400 -240 0
FLAG 160 -240 0
FLAG 64 416 0
FLAG 336 -240 0
FLAG -96 768 0
FLAG 208 576 dc-trim
FLAG 640 -512 0
FLAG 48 -240 0
FLAG 928 432 0
SYMBOL voltage -320 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 12 7 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V1
SYMATTR Value 6
SYMBOL res 496 256 R90
WINDOW 0 1 52 VBottom 2
WINDOW 3 33 45 VTop 2
SYMATTR InstName R11
SYMATTR Value 10.5k
SYMBOL cap 352 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 35 30 VTop 2
SYMATTR InstName C8
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL res 240 -144 R90
WINDOW 0 -1 46 VBottom 2
WINDOW 3 35 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 6.34k
SYMBOL res 448 -144 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R8
SYMATTR Value 13k
SYMBOL njf -128 -176 R90
WINDOW 0 -37 23 VRight 2
WINDOW 3 -9 -3 VRight 2
SYMATTR InstName J1
SYMATTR Value J112
SYMBOL voltage -320 400 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 10 0 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V2
SYMATTR Value 6
SYMBOL res 48 272 R0
WINDOW 3 36 65 Left 2
SYMATTR Value 10.5k
SYMATTR InstName R10
SYMBOL schottky 496 -288 R0
WINDOW 3 -17 -26 VRight 2
SYMATTR Value BAS40HY
SYMATTR InstName D1
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -112 -64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 82
SYMBOL OpAmps\\LT1994 176 128 R0
WINDOW 3 10 -65 Left 2
WINDOW 0 11 -95 Left 2
SYMATTR InstName U1
SYMBOL OpAmps\\LT1057 288 512 M0
WINDOW 0 19 104 Left 2
WINDOW 3 18 130 Left 2
SYMATTR InstName U3
SYMBOL schottky 528 448 M0
WINDOW 3 52 -26 VRight 2
WINDOW 0 -18 3 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 640 448 M0
WINDOW 3 49 -26 VRight 2
WINDOW 0 -21 4 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D4
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 528 608 M0
WINDOW 3 25 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R16
SYMBOL res 720 608 M0
WINDOW 3 27 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R17
SYMBOL res -112 -256 R0
WINDOW 0 38 42 Left 2
WINDOW 3 36 66 Left 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 320 -384 R0
WINDOW 0 -50 69 Left 2
WINDOW 3 -54 98 Left 2
SYMATTR InstName R13
SYMATTR Value 220k
SYMBOL res 448 -32 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R9
SYMATTR Value 1.0469Meg
SYMBOL res -80 -288 R180
WINDOW 0 40 70 Left 2
WINDOW 3 45 42 Left 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res -80 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 33k
SYMBOL res 176 416 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 220
SYMBOL res 16 560 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL cap 176 352 R180
WINDOW 0 -37 41 Left 2
WINDOW 3 -50 13 Left 2
SYMATTR InstName C7
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL cap 720 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 100000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.002 Lser=0 mfg="TDK" pn="C575OX5ROJI07M" type="X5R"
SYMBOL res 736 160 R0
SYMATTR InstName R18
SYMATTR Value 600
SYMBOL res 192 -400 R270
WINDOW 0 35 55 VTop 2
WINDOW 3 -6 55 VBottom 2
SYMATTR InstName R12
SYMATTR Value 220k
SYMBOL cap 176 -352 M0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 48 Left 2
SYMATTR InstName C6
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 -352 M0
WINDOW 0 -32 51 Left 2
WINDOW 3 -72 7 Left 2
SYMATTR InstName C10
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 368 448 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C9
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 640 R0
WINDOW 0 -37 6 Left 2
WINDOW 3 -77 53 Left 2
SYMATTR InstName C11
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 608 640 R0
WINDOW 0 -33 9 Left 2
WINDOW 3 -72 51 Left 2
SYMATTR InstName C12
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 160 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -79 48 Left 2
SYMATTR InstName C1
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 432 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 50 Left 2
SYMATTR InstName C2
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -16 224 R180
WINDOW 0 23 78 Left 2
WINDOW 3 -74 78 Left 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL diode -80 688 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL cap -64 688 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C5
SYMATTR Value 1000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM032R60J105ME05" type="X5R"
SYMBOL OpAmps\\LT1678 -32 -432 M0
WINDOW 0 -47 50 Left 2
WINDOW 3 -47 89 Left 2
SYMATTR InstName U2
SYMBOL diode 192 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D6
SYMATTR Value 1N914
SYMBOL diode 272 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D7
SYMATTR Value 1N914
SYMBOL diode 352 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D8
SYMATTR Value 1N914
SYMBOL diode 432 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D9
SYMATTR Value 1N914
SYMBOL diode 512 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D10
SYMATTR Value 1N914
SYMBOL schottky 608 -288 R0
SYMATTR Value BAS40HY
SYMATTR InstName D2
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -80 -560 R270
WINDOW 0 33 55 VTop 2
WINDOW 3 -3 55 VBottom 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 32 -384 R0
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL diode 592 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D11
SYMATTR Value 1N914
SYMBOL res 912 304 R0
SYMATTR InstName R19
SYMATTR Value 600
TEXT -624 272 Left 2 !.tran 0 150s 0s startup
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers.
This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place, even if the sim is left to run its
full course.
Also, what's the purpose of the 6 diodes in series at the
top of the schematic? If you need to drop 4V there ought to be a more
elegant way of doing it!
There are two things I don't understand about my own circuit.
1. Why does LT1678 work fine in position U2 but LT1057 does not.
2. Why is the DC stabilization circuit (U3 and associated components) needed and would it work just the same in reality?
Version 4
SHEET 1 2196 932
WIRE -64 -576 -96 -576
WIRE 48 -576 16 -576
WIRE 128 -528 112 -528
WIRE 208 -528 192 -528
WIRE 288 -528 272 -528
WIRE 368 -528 352 -528
WIRE 448 -528 432 -528
WIRE 528 -528 512 -528
WIRE 640 -528 592 -528
WIRE 640 -512 640 -528
WIRE -32 -464 -32 -480
WIRE 48 -448 48 -576
WIRE 48 -448 0 -448
WIRE -96 -432 -96 -576
WIRE -64 -432 -96 -432
WIRE 112 -416 112 -528
WIRE 112 -416 0 -416
WIRE 160 -416 112 -416
WIRE 208 -416 160 -416
WIRE 336 -416 288 -416
WIRE 400 -416 336 -416
WIRE 512 -416 400 -416
WIRE 624 -416 512 -416
WIRE -96 -384 -96 -432
WIRE -32 -384 -32 -400
WIRE 48 -368 48 -448
WIRE 336 -368 336 -416
WIRE 160 -352 160 -416
WIRE 400 -352 400 -416
WIRE 512 -288 512 -416
WIRE 624 -288 624 -416
WIRE -96 -272 -96 -304
WIRE -96 -272 -192 -272
WIRE -96 -240 -96 -272
WIRE 48 -240 48 -288
WIRE 160 -240 160 -288
WIRE 336 -240 336 -288
WIRE 400 -240 400 -288
WIRE -192 -176 -192 -272
WIRE -224 -128 -256 -128
WIRE -96 -128 -96 -160
WIRE -96 -128 -128 -128
WIRE -80 -128 -96 -128
WIRE 144 -128 -80 -128
WIRE 288 -128 224 -128
WIRE 352 -128 288 -128
WIRE 512 -128 512 -224
WIRE 512 -128 432 -128
WIRE -256 -48 -256 -128
WIRE -208 -48 -256 -48
WIRE -80 -48 -80 -128
WIRE -80 -48 -128 -48
WIRE 288 -16 288 -128
WIRE 288 -16 64 -16
WIRE 352 -16 288 -16
WIRE 512 -16 512 -128
WIRE 512 -16 432 -16
WIRE -256 0 -256 -48
WIRE 144 48 144 32
WIRE -240 96 -320 96
WIRE -176 96 -240 96
WIRE 64 96 64 -16
WIRE 112 96 64 96
WIRE 512 96 512 -16
WIRE 512 96 272 96
WIRE -32 128 -96 128
WIRE 112 128 -32 128
WIRE -320 144 -320 96
WIRE 624 144 624 -224
WIRE 656 144 624 144
WIRE 752 144 720 144
WIRE -176 160 -176 96
WIRE -32 160 -32 128
WIRE 112 160 64 160
WIRE 624 160 624 144
WIRE 624 160 272 160
WIRE 752 176 752 144
WIRE 144 224 144 208
WIRE -32 256 -32 224
WIRE 64 272 64 160
WIRE 160 272 64 272
WIRE 288 272 160 272
WIRE 400 272 352 272
WIRE 512 272 512 96
WIRE 512 272 480 272
WIRE 64 288 64 272
WIRE 160 288 160 272
WIRE 752 288 752 256
WIRE 880 288 752 288
WIRE 928 288 880 288
WIRE -320 320 -320 224
WIRE -320 320 -400 320
WIRE 928 320 928 288
WIRE -400 336 -400 320
WIRE -320 336 -320 320
WIRE -176 336 -176 224
WIRE -176 336 -320 336
WIRE -96 336 -96 128
WIRE 64 384 64 368
WIRE 160 384 160 352
WIRE 160 384 64 384
WIRE -320 416 -320 336
WIRE 64 416 64 384
WIRE -176 432 -176 336
WIRE 192 432 144 432
WIRE 304 432 272 432
WIRE 384 432 368 432
WIRE 928 432 928 400
WIRE 512 448 512 272
WIRE 624 448 624 160
WIRE 288 544 288 528
WIRE 384 560 384 432
WIRE 384 560 320 560
WIRE 624 560 624 512
WIRE 624 560 384 560
WIRE -96 576 -96 416
WIRE -48 576 -96 576
WIRE 32 576 -48 576
WIRE 144 576 144 432
WIRE 144 576 112 576
WIRE 208 576 144 576
WIRE 256 576 208 576
WIRE -320 592 -320 496
WIRE -240 592 -320 592
WIRE -176 592 -176 496
WIRE -176 592 -240 592
WIRE 432 592 320 592
WIRE 512 592 512 512
WIRE 512 592 432 592
WIRE 624 592 624 560
WIRE 704 592 624 592
WIRE -96 624 -96 576
WIRE -48 624 -48 576
WIRE 288 624 288 608
WIRE 512 624 512 592
WIRE 704 624 704 592
WIRE 432 640 432 592
WIRE 624 640 624 592
WIRE -96 736 -96 688
WIRE -48 736 -48 688
WIRE -48 736 -96 736
WIRE 432 736 432 704
WIRE 512 736 512 704
WIRE 512 736 432 736
WIRE 624 736 624 704
WIRE 624 736 512 736
WIRE 704 736 704 704
WIRE 704 736 624 736
WIRE -96 768 -96 736
WIRE 432 768 432 736
FLAG -400 336 0
FLAG 288 528 V+
FLAG 144 224 V-
FLAG -240 96 V+
FLAG -240 592 V-
FLAG 880 288 output
FLAG 144 32 V+
FLAG 288 624 V-
FLAG 432 768 0
FLAG -32 256 0
FLAG -32 -480 V+
FLAG -32 -384 V-
FLAG -256 0 0
FLAG 400 -240 0
FLAG 160 -240 0
FLAG 64 416 0
FLAG 336 -240 0
FLAG -96 768 0
FLAG 208 576 dc-trim
FLAG 640 -512 0
FLAG 48 -240 0
FLAG 928 432 0
SYMBOL voltage -320 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 12 7 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V1
SYMATTR Value 6
SYMBOL res 496 256 R90
WINDOW 0 1 52 VBottom 2
WINDOW 3 33 45 VTop 2
SYMATTR InstName R11
SYMATTR Value 10.5k
SYMBOL cap 352 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 35 30 VTop 2
SYMATTR InstName C8
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL res 240 -144 R90
WINDOW 0 -1 46 VBottom 2
WINDOW 3 35 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 6.34k
SYMBOL res 448 -144 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R8
SYMATTR Value 13k
SYMBOL njf -128 -176 R90
WINDOW 0 -37 23 VRight 2
WINDOW 3 -9 -3 VRight 2
SYMATTR InstName J1
SYMATTR Value J112
SYMBOL voltage -320 400 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 10 0 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V2
SYMATTR Value 6
SYMBOL res 48 272 R0
WINDOW 3 36 65 Left 2
SYMATTR Value 10.5k
SYMATTR InstName R10
SYMBOL schottky 496 -288 R0
WINDOW 3 -17 -26 VRight 2
SYMATTR Value BAS40HY
SYMATTR InstName D1
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -112 -64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 82
SYMBOL OpAmps\\LT1994 176 128 R0
WINDOW 3 10 -65 Left 2
WINDOW 0 11 -95 Left 2
SYMATTR InstName U1
SYMBOL OpAmps\\LT1057 288 512 M0
WINDOW 0 19 104 Left 2
WINDOW 3 18 130 Left 2
SYMATTR InstName U3
SYMBOL schottky 528 448 M0
WINDOW 3 52 -26 VRight 2
WINDOW 0 -18 3 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 640 448 M0
WINDOW 3 49 -26 VRight 2
WINDOW 0 -21 4 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D4
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 528 608 M0
WINDOW 3 25 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R16
SYMBOL res 720 608 M0
WINDOW 3 27 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R17
SYMBOL res -112 -256 R0
WINDOW 0 38 42 Left 2
WINDOW 3 36 66 Left 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 320 -384 R0
WINDOW 0 -50 69 Left 2
WINDOW 3 -54 98 Left 2
SYMATTR InstName R13
SYMATTR Value 220k
SYMBOL res 448 -32 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R9
SYMATTR Value 1.0469Meg
SYMBOL res -80 -288 R180
WINDOW 0 40 70 Left 2
WINDOW 3 45 42 Left 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res -80 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 33k
SYMBOL res 176 416 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 220
SYMBOL res 16 560 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL cap 176 352 R180
WINDOW 0 -37 41 Left 2
WINDOW 3 -50 13 Left 2
SYMATTR InstName C7
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL cap 720 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 100000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.002 Lser=0 mfg="TDK" pn="C575OX5ROJI07M" type="X5R"
SYMBOL res 736 160 R0
SYMATTR InstName R18
SYMATTR Value 600
SYMBOL res 192 -400 R270
WINDOW 0 35 55 VTop 2
WINDOW 3 -6 55 VBottom 2
SYMATTR InstName R12
SYMATTR Value 220k
SYMBOL cap 176 -352 M0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 48 Left 2
SYMATTR InstName C6
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 -352 M0
WINDOW 0 -32 51 Left 2
WINDOW 3 -72 7 Left 2
SYMATTR InstName C10
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 368 448 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C9
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 640 R0
WINDOW 0 -37 6 Left 2
WINDOW 3 -77 53 Left 2
SYMATTR InstName C11
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 608 640 R0
WINDOW 0 -33 9 Left 2
WINDOW 3 -72 51 Left 2
SYMATTR InstName C12
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 160 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -79 48 Left 2
SYMATTR InstName C1
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 432 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 50 Left 2
SYMATTR InstName C2
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -16 224 R180
WINDOW 0 23 78 Left 2
WINDOW 3 -74 78 Left 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL diode -80 688 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL cap -64 688 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C5
SYMATTR Value 1000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM032R60J105ME05" type="X5R"
SYMBOL OpAmps\\LT1678 -32 -432 M0
WINDOW 0 -47 50 Left 2
WINDOW 3 -47 89 Left 2
SYMATTR InstName U2
SYMBOL diode 192 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D6
SYMATTR Value 1N914
SYMBOL diode 272 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D7
SYMATTR Value 1N914
SYMBOL diode 352 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D8
SYMATTR Value 1N914
SYMBOL diode 432 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D9
SYMATTR Value 1N914
SYMBOL diode 512 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D10
SYMATTR Value 1N914
SYMBOL schottky 608 -288 R0
SYMATTR Value BAS40HY
SYMATTR InstName D2
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -80 -560 R270
WINDOW 0 33 55 VTop 2
WINDOW 3 -3 55 VBottom 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 32 -384 R0
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL diode 592 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D11
SYMATTR Value 1N914
SYMBOL res 912 304 R0
SYMATTR InstName R19
SYMATTR Value 600
TEXT -624 272 Left 2 !.tran 0 150s 0s startup
"Cursitor Doom" <cd@notformail.com> wrote in message news:bs81jjt7d064jc1ktmvihgn30qkhf67taj@4ax.com...
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers. >>>This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
Change R9 to 1.07Meg does it amplitude stabilize now?
Adjustment will be needed in any real circuit.
even if the sim is left to run its
full course. Also, what's the purpose of the 6 diodes in series at the
top of the schematic? If you need to drop 4V there ought to be a more
elegant way of doing it!
There are two things I don't understand about my own circuit.
1. Why does LT1678 work fine in position U2 but LT1057 does not.
2. Why is the DC stabilization circuit (U3 and associated components) needed and would it work just the same in reality?
Version 4
SHEET 1 2196 932
WIRE -64 -576 -96 -576
WIRE 48 -576 16 -576
WIRE 128 -528 112 -528
WIRE 208 -528 192 -528
WIRE 288 -528 272 -528
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FLAG 144 224 V-
FLAG -240 96 V+
FLAG -240 592 V-
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FLAG 144 32 V+
FLAG 288 624 V-
FLAG 432 768 0
FLAG -32 256 0
FLAG -32 -480 V+
FLAG -32 -384 V-
FLAG -256 0 0
FLAG 400 -240 0
FLAG 160 -240 0
FLAG 64 416 0
FLAG 336 -240 0
FLAG -96 768 0
FLAG 208 576 dc-trim
FLAG 640 -512 0
FLAG 48 -240 0
FLAG 928 432 0
SYMBOL voltage -320 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 12 7 Left 2
WINDOW 3 15 104 Left 2
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SYMBOL res 496 256 R90
WINDOW 0 1 52 VBottom 2
WINDOW 3 33 45 VTop 2
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SYMATTR Value 10.5k
SYMBOL cap 352 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 35 30 VTop 2
SYMATTR InstName C8
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
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WINDOW 0 -1 46 VBottom 2
WINDOW 3 35 56 VTop 2
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SYMBOL res 448 -144 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
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SYMBOL njf -128 -176 R90
WINDOW 0 -37 23 VRight 2
WINDOW 3 -9 -3 VRight 2
SYMATTR InstName J1
SYMATTR Value J112
SYMBOL voltage -320 400 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 10 0 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
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SYMBOL res 48 272 R0
WINDOW 3 36 65 Left 2
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SYMATTR InstName R10
SYMBOL schottky 496 -288 R0
WINDOW 3 -17 -26 VRight 2
SYMATTR Value BAS40HY
SYMATTR InstName D1
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -112 -64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 82
SYMBOL OpAmps\\LT1994 176 128 R0
WINDOW 3 10 -65 Left 2
WINDOW 0 11 -95 Left 2
SYMATTR InstName U1
SYMBOL OpAmps\\LT1057 288 512 M0
WINDOW 0 19 104 Left 2
WINDOW 3 18 130 Left 2
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SYMBOL schottky 528 448 M0
WINDOW 3 52 -26 VRight 2
WINDOW 0 -18 3 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 640 448 M0
WINDOW 3 49 -26 VRight 2
WINDOW 0 -21 4 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D4
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 528 608 M0
WINDOW 3 25 87 Left 2
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SYMBOL res 720 608 M0
WINDOW 3 27 87 Left 2
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SYMATTR InstName R17
SYMBOL res -112 -256 R0
WINDOW 0 38 42 Left 2
WINDOW 3 36 66 Left 2
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SYMBOL res 320 -384 R0
WINDOW 0 -50 69 Left 2
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SYMBOL res 448 -32 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
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SYMBOL res -80 -288 R180
WINDOW 0 40 70 Left 2
WINDOW 3 45 42 Left 2
SYMATTR InstName R1
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SYMBOL res -80 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
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SYMBOL res 176 416 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 220
SYMBOL res 16 560 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL cap 176 352 R180
WINDOW 0 -37 41 Left 2
WINDOW 3 -50 13 Left 2
SYMATTR InstName C7
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL cap 720 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 100000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.002 Lser=0 mfg="TDK" pn="C575OX5ROJI07M" type="X5R"
SYMBOL res 736 160 R0
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SYMATTR Value 600
SYMBOL res 192 -400 R270
WINDOW 0 35 55 VTop 2
WINDOW 3 -6 55 VBottom 2
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SYMATTR Value 220k
SYMBOL cap 176 -352 M0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 48 Left 2
SYMATTR InstName C6
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 -352 M0
WINDOW 0 -32 51 Left 2
WINDOW 3 -72 7 Left 2
SYMATTR InstName C10
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 368 448 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
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SYMBOL cap 416 640 R0
WINDOW 0 -37 6 Left 2
WINDOW 3 -77 53 Left 2
SYMATTR InstName C11
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 608 640 R0
WINDOW 0 -33 9 Left 2
WINDOW 3 -72 51 Left 2
SYMATTR InstName C12
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 160 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -79 48 Left 2
SYMATTR InstName C1
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 432 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 50 Left 2
SYMATTR InstName C2
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -16 224 R180
WINDOW 0 23 78 Left 2
WINDOW 3 -74 78 Left 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL diode -80 688 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL cap -64 688 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C5
SYMATTR Value 1000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM032R60J105ME05" type="X5R"
SYMBOL OpAmps\\LT1678 -32 -432 M0
WINDOW 0 -47 50 Left 2
WINDOW 3 -47 89 Left 2
SYMATTR InstName U2
SYMBOL diode 192 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D6
SYMATTR Value 1N914
SYMBOL diode 272 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D7
SYMATTR Value 1N914
SYMBOL diode 352 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D8
SYMATTR Value 1N914
SYMBOL diode 432 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D9
SYMATTR Value 1N914
SYMBOL diode 512 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D10
SYMATTR Value 1N914
SYMBOL schottky 608 -288 R0
SYMATTR Value BAS40HY
SYMATTR InstName D2
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -80 -560 R270
WINDOW 0 33 55 VTop 2
WINDOW 3 -3 55 VBottom 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 32 -384 R0
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL diode 592 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D11
SYMATTR Value 1N914
SYMBOL res 912 304 R0
SYMATTR InstName R19
SYMATTR Value 600
TEXT -624 272 Left 2 !.tran 0 150s 0s startup
On Sun, 10 Nov 2024 12:12:34 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Cursitor Doom" <cd@notformail.com> wrote in message news:bs81jjt7d064jc1ktmvihgn30qkhf67taj@4ax.com...
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers. >>>>This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
Change R9 to 1.07Meg does it amplitude stabilize now?
Adjustment will be needed in any real circuit.
Indeed, but for a simulation we should be seeing identical results!
I've made the change as you suggested and it's increased the sim time >considerably. I'll post again when it's completed.
even if the sim is left to run its
full course. Also, what's the purpose of the 6 diodes in series at the
top of the schematic? If you need to drop 4V there ought to be a more
elegant way of doing it!
There are two things I don't understand about my own circuit.
1. Why does LT1678 work fine in position U2 but LT1057 does not.
2. Why is the DC stabilization circuit (U3 and associated components) needed and would it work just the same in reality?
Version 4
SHEET 1 2196 932
WIRE -64 -576 -96 -576
WIRE 48 -576 16 -576
WIRE 128 -528 112 -528
WIRE 208 -528 192 -528
WIRE 288 -528 272 -528
WIRE 368 -528 352 -528
WIRE 448 -528 432 -528
WIRE 528 -528 512 -528
WIRE 640 -528 592 -528
WIRE 640 -512 640 -528
WIRE -32 -464 -32 -480
WIRE 48 -448 48 -576
WIRE 48 -448 0 -448
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WIRE -64 -432 -96 -432
WIRE 112 -416 112 -528
WIRE 112 -416 0 -416
WIRE 160 -416 112 -416
WIRE 208 -416 160 -416
WIRE 336 -416 288 -416
WIRE 400 -416 336 -416
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WIRE 624 -416 512 -416
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WIRE -32 -384 -32 -400
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WIRE 400 -352 400 -416
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WIRE -256 0 -256 -48
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WIRE 112 96 64 96
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WIRE 512 96 272 96
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WIRE 112 128 -32 128
WIRE -320 144 -320 96
WIRE 624 144 624 -224
WIRE 656 144 624 144
WIRE 752 144 720 144
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WIRE -32 160 -32 128
WIRE 112 160 64 160
WIRE 624 160 624 144
WIRE 624 160 272 160
WIRE 752 176 752 144
WIRE 144 224 144 208
WIRE -32 256 -32 224
WIRE 64 272 64 160
WIRE 160 272 64 272
WIRE 288 272 160 272
WIRE 400 272 352 272
WIRE 512 272 512 96
WIRE 512 272 480 272
WIRE 64 288 64 272
WIRE 160 288 160 272
WIRE 752 288 752 256
WIRE 880 288 752 288
WIRE 928 288 880 288
WIRE -320 320 -320 224
WIRE -320 320 -400 320
WIRE 928 320 928 288
WIRE -400 336 -400 320
WIRE -320 336 -320 320
WIRE -176 336 -176 224
WIRE -176 336 -320 336
WIRE -96 336 -96 128
WIRE 64 384 64 368
WIRE 160 384 160 352
WIRE 160 384 64 384
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WIRE 64 416 64 384
WIRE -176 432 -176 336
WIRE 192 432 144 432
WIRE 304 432 272 432
WIRE 384 432 368 432
WIRE 928 432 928 400
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WIRE 624 448 624 160
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WIRE 384 560 320 560
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WIRE 624 560 384 560
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WIRE 32 576 -48 576
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WIRE 256 576 208 576
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WIRE -240 592 -320 592
WIRE -176 592 -176 496
WIRE -176 592 -240 592
WIRE 432 592 320 592
WIRE 512 592 512 512
WIRE 512 592 432 592
WIRE 624 592 624 560
WIRE 704 592 624 592
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WIRE -48 624 -48 576
WIRE 288 624 288 608
WIRE 512 624 512 592
WIRE 704 624 704 592
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WIRE 624 640 624 592
WIRE -96 736 -96 688
WIRE -48 736 -48 688
WIRE -48 736 -96 736
WIRE 432 736 432 704
WIRE 512 736 512 704
WIRE 512 736 432 736
WIRE 624 736 624 704
WIRE 624 736 512 736
WIRE 704 736 704 704
WIRE 704 736 624 736
WIRE -96 768 -96 736
WIRE 432 768 432 736
FLAG -400 336 0
FLAG 288 528 V+
FLAG 144 224 V-
FLAG -240 96 V+
FLAG -240 592 V-
FLAG 880 288 output
FLAG 144 32 V+
FLAG 288 624 V-
FLAG 432 768 0
FLAG -32 256 0
FLAG -32 -480 V+
FLAG -32 -384 V-
FLAG -256 0 0
FLAG 400 -240 0
FLAG 160 -240 0
FLAG 64 416 0
FLAG 336 -240 0
FLAG -96 768 0
FLAG 208 576 dc-trim
FLAG 640 -512 0
FLAG 48 -240 0
FLAG 928 432 0
SYMBOL voltage -320 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 12 7 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
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SYMATTR Value 6
SYMBOL res 496 256 R90
WINDOW 0 1 52 VBottom 2
WINDOW 3 33 45 VTop 2
SYMATTR InstName R11
SYMATTR Value 10.5k
SYMBOL cap 352 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 35 30 VTop 2
SYMATTR InstName C8
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL res 240 -144 R90
WINDOW 0 -1 46 VBottom 2
WINDOW 3 35 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 6.34k
SYMBOL res 448 -144 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R8
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SYMBOL njf -128 -176 R90
WINDOW 0 -37 23 VRight 2
WINDOW 3 -9 -3 VRight 2
SYMATTR InstName J1
SYMATTR Value J112
SYMBOL voltage -320 400 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 10 0 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V2
SYMATTR Value 6
SYMBOL res 48 272 R0
WINDOW 3 36 65 Left 2
SYMATTR Value 10.5k
SYMATTR InstName R10
SYMBOL schottky 496 -288 R0
WINDOW 3 -17 -26 VRight 2
SYMATTR Value BAS40HY
SYMATTR InstName D1
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -112 -64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 82
SYMBOL OpAmps\\LT1994 176 128 R0
WINDOW 3 10 -65 Left 2
WINDOW 0 11 -95 Left 2
SYMATTR InstName U1
SYMBOL OpAmps\\LT1057 288 512 M0
WINDOW 0 19 104 Left 2
WINDOW 3 18 130 Left 2
SYMATTR InstName U3
SYMBOL schottky 528 448 M0
WINDOW 3 52 -26 VRight 2
WINDOW 0 -18 3 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 640 448 M0
WINDOW 3 49 -26 VRight 2
WINDOW 0 -21 4 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D4
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 528 608 M0
WINDOW 3 25 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R16
SYMBOL res 720 608 M0
WINDOW 3 27 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R17
SYMBOL res -112 -256 R0
WINDOW 0 38 42 Left 2
WINDOW 3 36 66 Left 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 320 -384 R0
WINDOW 0 -50 69 Left 2
WINDOW 3 -54 98 Left 2
SYMATTR InstName R13
SYMATTR Value 220k
SYMBOL res 448 -32 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R9
SYMATTR Value 1.0469Meg
SYMBOL res -80 -288 R180
WINDOW 0 40 70 Left 2
WINDOW 3 45 42 Left 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res -80 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 33k
SYMBOL res 176 416 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 220
SYMBOL res 16 560 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL cap 176 352 R180
WINDOW 0 -37 41 Left 2
WINDOW 3 -50 13 Left 2
SYMATTR InstName C7
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL cap 720 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 100000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.002 Lser=0 mfg="TDK" pn="C575OX5ROJI07M" type="X5R"
SYMBOL res 736 160 R0
SYMATTR InstName R18
SYMATTR Value 600
SYMBOL res 192 -400 R270
WINDOW 0 35 55 VTop 2
WINDOW 3 -6 55 VBottom 2
SYMATTR InstName R12
SYMATTR Value 220k
SYMBOL cap 176 -352 M0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 48 Left 2
SYMATTR InstName C6
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 -352 M0
WINDOW 0 -32 51 Left 2
WINDOW 3 -72 7 Left 2
SYMATTR InstName C10
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 368 448 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C9
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 640 R0
WINDOW 0 -37 6 Left 2
WINDOW 3 -77 53 Left 2
SYMATTR InstName C11
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 608 640 R0
WINDOW 0 -33 9 Left 2
WINDOW 3 -72 51 Left 2
SYMATTR InstName C12
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 160 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -79 48 Left 2
SYMATTR InstName C1
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 432 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 50 Left 2
SYMATTR InstName C2
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -16 224 R180
WINDOW 0 23 78 Left 2
WINDOW 3 -74 78 Left 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL diode -80 688 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL cap -64 688 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C5
SYMATTR Value 1000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM032R60J105ME05" type="X5R"
SYMBOL OpAmps\\LT1678 -32 -432 M0
WINDOW 0 -47 50 Left 2
WINDOW 3 -47 89 Left 2
SYMATTR InstName U2
SYMBOL diode 192 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D6
SYMATTR Value 1N914
SYMBOL diode 272 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D7
SYMATTR Value 1N914
SYMBOL diode 352 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D8
SYMATTR Value 1N914
SYMBOL diode 432 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D9
SYMATTR Value 1N914
SYMBOL diode 512 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D10
SYMATTR Value 1N914
SYMBOL schottky 608 -288 R0
SYMATTR Value BAS40HY
SYMATTR InstName D2
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -80 -560 R270
WINDOW 0 33 55 VTop 2
WINDOW 3 -3 55 VBottom 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 32 -384 R0
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL diode 592 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D11
SYMATTR Value 1N914
SYMBOL res 912 304 R0
SYMATTR InstName R19
SYMATTR Value 600
TEXT -624 272 Left 2 !.tran 0 150s 0s startup
On Sun, 10 Nov 2024 17:45:00 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 10 Nov 2024 12:12:34 -0500, "Edward Rawde" >><invalid@invalid.invalid> wrote:
"Cursitor Doom" <cd@notformail.com> wrote in message news:bs81jjt7d064jc1ktmvihgn30qkhf67taj@4ax.com...
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers. >>>>>This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
Change R9 to 1.07Meg does it amplitude stabilize now?
Adjustment will be needed in any real circuit.
Indeed, but for a simulation we should be seeing identical results!
I've made the change as you suggested and it's increased the sim time >>considerably. I'll post again when it's completed.
Update: looking *much* better at 25% done. Settled after 7.5s. I will
let it run its course anyway and post again at the end with the final >outcome.
even if the sim is left to run its
full course. Also, what's the purpose of the 6 diodes in series at the >>>> top of the schematic? If you need to drop 4V there ought to be a more
elegant way of doing it!
There are two things I don't understand about my own circuit.
1. Why does LT1678 work fine in position U2 but LT1057 does not.
2. Why is the DC stabilization circuit (U3 and associated components) needed and would it work just the same in reality?
Version 4
SHEET 1 2196 932
WIRE -64 -576 -96 -576
WIRE 48 -576 16 -576
WIRE 128 -528 112 -528
WIRE 208 -528 192 -528
WIRE 288 -528 272 -528
WIRE 368 -528 352 -528
WIRE 448 -528 432 -528
WIRE 528 -528 512 -528
WIRE 640 -528 592 -528
WIRE 640 -512 640 -528
WIRE -32 -464 -32 -480
WIRE 48 -448 48 -576
WIRE 48 -448 0 -448
WIRE -96 -432 -96 -576
WIRE -64 -432 -96 -432
WIRE 112 -416 112 -528
WIRE 112 -416 0 -416
WIRE 160 -416 112 -416
WIRE 208 -416 160 -416
WIRE 336 -416 288 -416
WIRE 400 -416 336 -416
WIRE 512 -416 400 -416
WIRE 624 -416 512 -416
WIRE -96 -384 -96 -432
WIRE -32 -384 -32 -400
WIRE 48 -368 48 -448
WIRE 336 -368 336 -416
WIRE 160 -352 160 -416
WIRE 400 -352 400 -416
WIRE 512 -288 512 -416
WIRE 624 -288 624 -416
WIRE -96 -272 -96 -304
WIRE -96 -272 -192 -272
WIRE -96 -240 -96 -272
WIRE 48 -240 48 -288
WIRE 160 -240 160 -288
WIRE 336 -240 336 -288
WIRE 400 -240 400 -288
WIRE -192 -176 -192 -272
WIRE -224 -128 -256 -128
WIRE -96 -128 -96 -160
WIRE -96 -128 -128 -128
WIRE -80 -128 -96 -128
WIRE 144 -128 -80 -128
WIRE 288 -128 224 -128
WIRE 352 -128 288 -128
WIRE 512 -128 512 -224
WIRE 512 -128 432 -128
WIRE -256 -48 -256 -128
WIRE -208 -48 -256 -48
WIRE -80 -48 -80 -128
WIRE -80 -48 -128 -48
WIRE 288 -16 288 -128
WIRE 288 -16 64 -16
WIRE 352 -16 288 -16
WIRE 512 -16 512 -128
WIRE 512 -16 432 -16
WIRE -256 0 -256 -48
WIRE 144 48 144 32
WIRE -240 96 -320 96
WIRE -176 96 -240 96
WIRE 64 96 64 -16
WIRE 112 96 64 96
WIRE 512 96 512 -16
WIRE 512 96 272 96
WIRE -32 128 -96 128
WIRE 112 128 -32 128
WIRE -320 144 -320 96
WIRE 624 144 624 -224
WIRE 656 144 624 144
WIRE 752 144 720 144
WIRE -176 160 -176 96
WIRE -32 160 -32 128
WIRE 112 160 64 160
WIRE 624 160 624 144
WIRE 624 160 272 160
WIRE 752 176 752 144
WIRE 144 224 144 208
WIRE -32 256 -32 224
WIRE 64 272 64 160
WIRE 160 272 64 272
WIRE 288 272 160 272
WIRE 400 272 352 272
WIRE 512 272 512 96
WIRE 512 272 480 272
WIRE 64 288 64 272
WIRE 160 288 160 272
WIRE 752 288 752 256
WIRE 880 288 752 288
WIRE 928 288 880 288
WIRE -320 320 -320 224
WIRE -320 320 -400 320
WIRE 928 320 928 288
WIRE -400 336 -400 320
WIRE -320 336 -320 320
WIRE -176 336 -176 224
WIRE -176 336 -320 336
WIRE -96 336 -96 128
WIRE 64 384 64 368
WIRE 160 384 160 352
WIRE 160 384 64 384
WIRE -320 416 -320 336
WIRE 64 416 64 384
WIRE -176 432 -176 336
WIRE 192 432 144 432
WIRE 304 432 272 432
WIRE 384 432 368 432
WIRE 928 432 928 400
WIRE 512 448 512 272
WIRE 624 448 624 160
WIRE 288 544 288 528
WIRE 384 560 384 432
WIRE 384 560 320 560
WIRE 624 560 624 512
WIRE 624 560 384 560
WIRE -96 576 -96 416
WIRE -48 576 -96 576
WIRE 32 576 -48 576
WIRE 144 576 144 432
WIRE 144 576 112 576
WIRE 208 576 144 576
WIRE 256 576 208 576
WIRE -320 592 -320 496
WIRE -240 592 -320 592
WIRE -176 592 -176 496
WIRE -176 592 -240 592
WIRE 432 592 320 592
WIRE 512 592 512 512
WIRE 512 592 432 592
WIRE 624 592 624 560
WIRE 704 592 624 592
WIRE -96 624 -96 576
WIRE -48 624 -48 576
WIRE 288 624 288 608
WIRE 512 624 512 592
WIRE 704 624 704 592
WIRE 432 640 432 592
WIRE 624 640 624 592
WIRE -96 736 -96 688
WIRE -48 736 -48 688
WIRE -48 736 -96 736
WIRE 432 736 432 704
WIRE 512 736 512 704
WIRE 512 736 432 736
WIRE 624 736 624 704
WIRE 624 736 512 736
WIRE 704 736 704 704
WIRE 704 736 624 736
WIRE -96 768 -96 736
WIRE 432 768 432 736
FLAG -400 336 0
FLAG 288 528 V+
FLAG 144 224 V-
FLAG -240 96 V+
FLAG -240 592 V-
FLAG 880 288 output
FLAG 144 32 V+
FLAG 288 624 V-
FLAG 432 768 0
FLAG -32 256 0
FLAG -32 -480 V+
FLAG -32 -384 V-
FLAG -256 0 0
FLAG 400 -240 0
FLAG 160 -240 0
FLAG 64 416 0
FLAG 336 -240 0
FLAG -96 768 0
FLAG 208 576 dc-trim
FLAG 640 -512 0
FLAG 48 -240 0
FLAG 928 432 0
SYMBOL voltage -320 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 12 7 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V1
SYMATTR Value 6
SYMBOL res 496 256 R90
WINDOW 0 1 52 VBottom 2
WINDOW 3 33 45 VTop 2
SYMATTR InstName R11
SYMATTR Value 10.5k
SYMBOL cap 352 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 35 30 VTop 2
SYMATTR InstName C8
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL res 240 -144 R90
WINDOW 0 -1 46 VBottom 2
WINDOW 3 35 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 6.34k
SYMBOL res 448 -144 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R8
SYMATTR Value 13k
SYMBOL njf -128 -176 R90
WINDOW 0 -37 23 VRight 2
WINDOW 3 -9 -3 VRight 2
SYMATTR InstName J1
SYMATTR Value J112
SYMBOL voltage -320 400 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 10 0 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V2
SYMATTR Value 6
SYMBOL res 48 272 R0
WINDOW 3 36 65 Left 2
SYMATTR Value 10.5k
SYMATTR InstName R10
SYMBOL schottky 496 -288 R0
WINDOW 3 -17 -26 VRight 2
SYMATTR Value BAS40HY
SYMATTR InstName D1
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -112 -64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 82
SYMBOL OpAmps\\LT1994 176 128 R0
WINDOW 3 10 -65 Left 2
WINDOW 0 11 -95 Left 2
SYMATTR InstName U1
SYMBOL OpAmps\\LT1057 288 512 M0
WINDOW 0 19 104 Left 2
WINDOW 3 18 130 Left 2
SYMATTR InstName U3
SYMBOL schottky 528 448 M0
WINDOW 3 52 -26 VRight 2
WINDOW 0 -18 3 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 640 448 M0
WINDOW 3 49 -26 VRight 2
WINDOW 0 -21 4 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D4
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 528 608 M0
WINDOW 3 25 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R16
SYMBOL res 720 608 M0
WINDOW 3 27 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R17
SYMBOL res -112 -256 R0
WINDOW 0 38 42 Left 2
WINDOW 3 36 66 Left 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 320 -384 R0
WINDOW 0 -50 69 Left 2
WINDOW 3 -54 98 Left 2
SYMATTR InstName R13
SYMATTR Value 220k
SYMBOL res 448 -32 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R9
SYMATTR Value 1.0469Meg
SYMBOL res -80 -288 R180
WINDOW 0 40 70 Left 2
WINDOW 3 45 42 Left 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res -80 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 33k
SYMBOL res 176 416 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 220
SYMBOL res 16 560 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL cap 176 352 R180
WINDOW 0 -37 41 Left 2
WINDOW 3 -50 13 Left 2
SYMATTR InstName C7
SYMATTR Value 15n
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL cap 720 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 100000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.002 Lser=0 mfg="TDK" pn="C575OX5ROJI07M" type="X5R"
SYMBOL res 736 160 R0
SYMATTR InstName R18
SYMATTR Value 600
SYMBOL res 192 -400 R270
WINDOW 0 35 55 VTop 2
WINDOW 3 -6 55 VBottom 2
SYMATTR InstName R12
SYMATTR Value 220k
SYMBOL cap 176 -352 M0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 48 Left 2
SYMATTR InstName C6
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 -352 M0
WINDOW 0 -32 51 Left 2
WINDOW 3 -72 7 Left 2
SYMATTR InstName C10
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 368 448 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C9
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 640 R0
WINDOW 0 -37 6 Left 2
WINDOW 3 -77 53 Left 2
SYMATTR InstName C11
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 608 640 R0
WINDOW 0 -33 9 Left 2
WINDOW 3 -72 51 Left 2
SYMATTR InstName C12
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 160 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -79 48 Left 2
SYMATTR InstName C1
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 432 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -75 50 Left 2
SYMATTR InstName C2
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -16 224 R180
WINDOW 0 23 78 Left 2
WINDOW 3 -74 78 Left 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL diode -80 688 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL cap -64 688 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C5
SYMATTR Value 1000n
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM032R60J105ME05" type="X5R"
SYMBOL OpAmps\\LT1678 -32 -432 M0
WINDOW 0 -47 50 Left 2
WINDOW 3 -47 89 Left 2
SYMATTR InstName U2
SYMBOL diode 192 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D6
SYMATTR Value 1N914
SYMBOL diode 272 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D7
SYMATTR Value 1N914
SYMBOL diode 352 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D8
SYMATTR Value 1N914
SYMBOL diode 432 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D9
SYMATTR Value 1N914
SYMBOL diode 512 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D10
SYMATTR Value 1N914
SYMBOL schottky 608 -288 R0
SYMATTR Value BAS40HY
SYMATTR InstName D2
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -80 -560 R270
WINDOW 0 33 55 VTop 2
WINDOW 3 -3 55 VBottom 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 32 -384 R0
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL diode 592 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D11
SYMATTR Value 1N914
SYMBOL res 912 304 R0
SYMATTR InstName R19
SYMATTR Value 600
TEXT -624 272 Left 2 !.tran 0 150s 0s startup
On Sun, 10 Nov 2024 18:00:01 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 10 Nov 2024 17:45:00 +0000, Cursitor Doom <cd@notformail.com> >>wrote:
On Sun, 10 Nov 2024 12:12:34 -0500, "Edward Rawde" >>><invalid@invalid.invalid> wrote:
"Cursitor Doom" <cd@notformail.com> wrote in message news:bs81jjt7d064jc1ktmvihgn30qkhf67taj@4ax.com...
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers. >>>>>>This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many
harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
Change R9 to 1.07Meg does it amplitude stabilize now?
Adjustment will be needed in any real circuit.
Indeed, but for a simulation we should be seeing identical results!
I've made the change as you suggested and it's increased the sim time >>>considerably. I'll post again when it's completed.
Update: looking *much* better at 25% done. Settled after 7.5s. I will
let it run its course anyway and post again at the end with the final >>outcome.
Looks really stable now; 4.5V peak to peak and none of the
fluctuations of the earlier simulations. Weird how it took *so* much
longer to complete this time, though.
"Edward Rawde" <invalid@invalid.invalid> wrote in message news:vgrbl7$30bo$1@nnrp.usenet.blueworldhosting.com...
"Cursitor Doom" <cd@notformail.com> wrote in message news:ee92jjllg5kudr83e8bvvbsjba754aecjs@4ax.com...To answer my own question a wild guess says that the simulation model is hard coded to keep the output 2V away from the rail.
On Sun, 10 Nov 2024 18:00:01 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 10 Nov 2024 17:45:00 +0000, Cursitor Doom <cd@notformail.com> >>>>wrote:
On Sun, 10 Nov 2024 12:12:34 -0500, "Edward Rawde" >>>>><invalid@invalid.invalid> wrote:
"Cursitor Doom" <cd@notformail.com> wrote in message news:bs81jjt7d064jc1ktmvihgn30qkhf67taj@4ax.com...
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers. >>>>>>>>This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many
harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
Change R9 to 1.07Meg does it amplitude stabilize now?
Adjustment will be needed in any real circuit.
Indeed, but for a simulation we should be seeing identical results! >>>>>I've made the change as you suggested and it's increased the sim time >>>>>considerably. I'll post again when it's completed.
Update: looking *much* better at 25% done. Settled after 7.5s. I will >>>>let it run its course anyway and post again at the end with the final >>>>outcome.
Looks really stable now; 4.5V peak to peak and none of the
fluctuations of the earlier simulations. Weird how it took *so* much
longer to complete this time, though.
An FFT on the last 10 seconds should show peformance approaching 90dB down. >>
I likely won't be woBerking on this any further unless anyone else wants further discussion.
The goal was to get the purest possible sine wave at the lowest cost and in simulation I don't think I can improve on this
circuit.
I'm not able to build this circuit and even if I did I don't have equipment capable of measuring distortion 90dB down.
I'd still like to know why LT1057 doesn't work in position U2. It's not like rail to rail is needed.
LT1678 works exactly as expected. LT1057 probably would in reality but not sure I'd risk it.
Seems pretty poor to me that an op amp operating on 6V can't do more than 4V out.
I wonder what a real device would do.
The LT1678 works because it's rail to rail.
"Cursitor Doom" <cd@notformail.com> wrote in message news:ee92jjllg5kudr83e8bvvbsjba754aecjs@4ax.com...
On Sun, 10 Nov 2024 18:00:01 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 10 Nov 2024 17:45:00 +0000, Cursitor Doom <cd@notformail.com> >>>wrote:
On Sun, 10 Nov 2024 12:12:34 -0500, "Edward Rawde" >>>><invalid@invalid.invalid> wrote:
"Cursitor Doom" <cd@notformail.com> wrote in message news:bs81jjt7d064jc1ktmvihgn30qkhf67taj@4ax.com...
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers. >>>>>>>This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many
harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
Change R9 to 1.07Meg does it amplitude stabilize now?
Adjustment will be needed in any real circuit.
Indeed, but for a simulation we should be seeing identical results! >>>>I've made the change as you suggested and it's increased the sim time >>>>considerably. I'll post again when it's completed.
Update: looking *much* better at 25% done. Settled after 7.5s. I will
let it run its course anyway and post again at the end with the final >>>outcome.
Looks really stable now; 4.5V peak to peak and none of the
fluctuations of the earlier simulations. Weird how it took *so* much
longer to complete this time, though.
An FFT on the last 10 seconds should show peformance approaching 90dB down.
I likely won't be working on this any further unless anyone else wants further discussion.
The goal was to get the purest possible sine wave at the lowest cost and in simulation I don't think I can improve on this
circuit.
I'm not able to build this circuit and even if I did I don't have equipment capable of measuring distortion 90dB down.
I'd still like to know why LT1057 doesn't work in position U2. It's not like rail to rail is needed.
LT1678 works exactly as expected. LT1057 probably would in reality but not sure I'd risk it.
"Cursitor Doom" <cd@notformail.com> wrote in message news:ee92jjllg5kudr83e8bvvbsjba754aecjs@4ax.com...
On Sun, 10 Nov 2024 18:00:01 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 10 Nov 2024 17:45:00 +0000, Cursitor Doom <cd@notformail.com> >>>wrote:
On Sun, 10 Nov 2024 12:12:34 -0500, "Edward Rawde" >>>><invalid@invalid.invalid> wrote:
"Cursitor Doom" <cd@notformail.com> wrote in message news:bs81jjt7d064jc1ktmvihgn30qkhf67taj@4ax.com...
On Sun, 10 Nov 2024 00:49:36 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
On 9/11/2024 7:39 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
I have fixed my circuit but it raises more questions than it answers. >>>>>>>This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many
harmonics
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.
Spectral purity might be fine for all I can tell but the output
amplitude is all over the place,
Change R9 to 1.07Meg does it amplitude stabilize now?
Adjustment will be needed in any real circuit.
Indeed, but for a simulation we should be seeing identical results! >>>>I've made the change as you suggested and it's increased the sim time >>>>considerably. I'll post again when it's completed.
Update: looking *much* better at 25% done. Settled after 7.5s. I will
let it run its course anyway and post again at the end with the final >>>outcome.
Looks really stable now; 4.5V peak to peak and none of the
fluctuations of the earlier simulations. Weird how it took *so* much
longer to complete this time, though.
An FFT on the last 10 seconds should show peformance approaching 90dB down.
I likely won't be working on this any further unless anyone else wants further discussion.
The goal was to get the purest possible sine wave at the lowest cost and in simulation I don't think I can improve on this circuit.
I'm not able to build this circuit and even if I did I don't have equipment capable of measuring distortion 90dB down.
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
If a prototype is ever built, attention to the type and quality of the capacitors used will be needed.
Electrolytics are not intended. Put C1 and C2 near U1 supply pins.
On 9/11/2024 7:43 am, Edward Rawde wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
If a prototype is ever built, attention to the type and quality of the capacitors used will be needed.
Electrolytics are not intended. Put C1 and C2 near U1 supply pins.
If electrolytics are not intended, why are most of the capacitors rated at 10V?
When I cut and pasted the file the capacitors were mostly labelled as 10?, 1? and - in the case of the wein bridge capacitors
0.015?
The 15nF capacitors are rated at 16V - the polypropylene parts you can actually buy that are offered with a +/-1% tolerance are
63V and 250V parts
I presume you intended u or the Greek mu symbol, and after I'd done that substitution the simulation did work, if not well.
The feedback loop doesn't settle well, and I suspect that I know why. R4 should probably be in series with C3, not in parallel.
More later.
--
Bill Sloman, Sydney
--
Bill Sloman, Sydney
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
If a prototype is ever built, attention to the type and quality of the capacitors used will be needed.
Electrolytics are not intended. Put C1 and C2 near U1 supply pins.
Also pay attention to the stability of +/- 6V.
It would be nice to have a single 12V rail version but so far I can't get it to work.
R1 and R2 and probably R7 should be easily changeable.
R3 should be 220 ohm ten turn. R9 should be 1M ohm ten turn in series with 470k.
I don't fully understand why the DC stabilization circuit through U2B achieves what it does
and this makes me concerned about whether a real circuit would have the same behaviour.
It was added when I noticed that the diodes D1 and D2 weren't contributing equally so I
decided to try to derive a DC correction signal. This was originally connected to the FET source
and then to R13. Since this is a DC correction signal I decided to try out the effect of
connecting it to U1 Vocm and was amazed that this works as well as it does. >>If you disconnect R5, harmonics will not be more than 50dB down because D1 and D2 are no
longer providing stable and equal contributions to the level control feedback.
If you need even better performance then the circuit referenced by Bill Sloman can be used.
https://www.google.com/search?q=AN132+purity
NSL-32SR3 is not expensive and simulation models exist but LT1468 is expensive.
Other references
https://www.google.com/search?&q=The+field+effect+transistor+as+a+voltage+controlled+resistor
https://www.google.com/search?&q=sine+wave+oscillator&udm=2
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TEXT -624 272 Left 2 !.tran 0 300s 0s startup
TEXT -1568 -728 Left 2 ;Edward Rawde's high purity 1kHz sinewave oscillator. 8 Nov 2024\n \nHarmonics are more than 80dB down in
simulation.\nFFT the last 30 seconds.\nThere is only one harmonic stopping me claiming 90dB but the exact FFT result can
depend\non
exactly how much output is selected for the FFT. You may see different results.\n \nIf a prototype is ever built, pay attention to
the type and quality of the capacitors used.\nElectrolytics are not intended. Put C1 and C2 near U1 supply pins.\nAlso pay
attention
to the stability of +/- 6V.\nIt would be nice to have a single 12V rail version but so far I can't get it to work.\n \nR1 and R2
and
probably R7 should be easily changeable.\nR3 should be 220 ohm ten turn. R9 should be 1M ohm ten turn in series with 470k.\n \nI
don't fully understand why the DC stabilization circuit through U2B achieves what it does\nand this makes me concerned about
whether
a real circuit would have the same behaviour.\nIt was added when I noticed that the diodes D1 and D2 weren't contributing equally
so
I \ndecided to try to derive a DC correction signal. This was originally connected to the FET source\nand then to R13. Since this
is
a DC correction signal I decided to try out the effect of\nconnecting it to U1 Vocm and was amazed that this works as well as it
does. \nIf you disconnect R5, harmonics will not be more than 50dB down because D1 and D2 are no\nlonger providing stable and
equal
contributions to the level control feedback.\n \nIf you need even better performance then the circuit referenced by Bill Sloman
can
be used.\nhttps://www.google.com/search?q=AN132+purity\nNSL-32SR3 is not expensive and simulation models exist but LT1468 is
expensive.\n \nOther references\n >>\nhttps://www.google.com/search?&q=The+field+effect+transistor+as+a+voltage+controlled+resistor\n
\nhttps://www.google.com/search?&q=sine+wave+oscillator&udm=2
Using an NSL-32SR3 doesn't really gain you anything over a FET. If
you keep |vds| much less than |Vt-vgs| in the circuit and compensate
for the vds/2 variation on the gate drive the distortion levels
produced will be lower than almost all opamps out there. Here's a
link to a sim using an LDR.
https://1drv.ms/f/c/1af24d72a509cd48/EkjNCaVyTfIggBrrAQAAAAABHXNKs52BoVHi7zaxKmdMMQ?e=oVD0JS
I've added some 3rd harmonic distortion to a linear model to give
distortion figures roughly in the ballpark of Fig 6 in the attached application note (for small signal swings across the device). In the oscillator o/p the 3rd is about 150dB down. If you use the linear LDR
model, or a FET, it will be much the same. (The opamps used in the sim actually have distortions specs of about 130dB in reallity.)
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
On 15/11/2024 3:14 am, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I finally got around to digging out my AD734 based Wein bridge simulation, and created a FET based version.
It's got a nasty 163kHz generator embedded in it somewhere, and I've put in an RL filter to keep that under control.
The double Sallen and Keys network is a four pole Bessel filter which I'm using as a 250usec delay line - the output from the full
wave rectifier has an appreciable 2kHz component, but the delayed contribution coming into the integrator through R9 roughly
cancels the direct input through R20.
R10 in the integrator damps the amplitude feedback loop for a dead-beat response.
The harmonics in the 1kHz output are about 100dB below the fundamental. Not great, but respectable, and not worth trying to
improve in a simulation.
The circuit still works with the worst case values for the 1% capacitors at C5 and C6.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vh72bm$3b6ip$1@dont-email.me...
On 15/11/2024 3:14 am, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I finally got around to digging out my AD734 based Wein bridge simulation, and created a FET based version.
It's got a nasty 163kHz generator embedded in it somewhere, and I've put in an RL filter to keep that under control.
The double Sallen and Keys network is a four pole Bessel filter which I'm using as a 250usec delay line - the output from the full
wave rectifier has an appreciable 2kHz component, but the delayed contribution coming into the integrator through R9 roughly
cancels the direct input through R20.
R10 in the integrator damps the amplitude feedback loop for a dead-beat response.
The harmonics in the 1kHz output are about 100dB below the fundamental. Not great, but respectable, and not worth trying to
improve in a simulation.
The circuit still works with the worst case values for the 1% capacitors at C5 and C6.
After fixing line wraps and the position of U1 I need LME49710.lib
I'll be back in a few days.
On 15/11/2024 3:14 am, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I finally got around to digging out my AD734 based Wein bridge
simulation, and created a FET based version.
It's got a nasty 163kHz generator embedded in it somewhere, and I've put
in an RL filter to keep that under control.
On 15/11/2024 3:14 am, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I finally got around to digging out my AD734 based Wein bridge
simulation, and created a FET based version.
It's got a nasty 163kHz generator embedded in it somewhere, and I've put
in an RL filter to keep that under control.
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"...
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
This is the simplest circuit I can come up with.
Using an NSL-32SR3 doesn't really gain you anything over a FET. If
you keep |vds| much less than |Vt-vgs| in the circuit and compensate
for the vds/2 variation on the gate drive the distortion levels
produced will be lower than almost all opamps out there. Here's a
link to a sim using an LDR.
https://1drv.ms/f/c/1af24d72a509cd48/EkjNCaVyTfIggBrrAQAAAAABHXNKs52BoVHi7zaxKmdMMQ?e=oVD0JS
I've added some 3rd harmonic distortion to a linear model to give
distortion figures roughly in the ballpark of Fig 6 in the attached
application note (for small signal swings across the device). In the
oscillator o/p the 3rd is about 150dB down. If you use the linear LDR
model, or a FET, it will be much the same. (The opamps used in the sim
actually have distortions specs of about 130dB in reallity.)
Thanks for that. I left it overnight for 100 seconds of simulation. It looks like it has better harmonic performance than my
circuit.
Why use two op amps in the oscillator instead of one like my circuit?
Because of common mode (non)linearity. In most op-amps (especially
older designs) the distortion generated by the common mode signal is typically one to two orders of magnitude larger than the transfer
distortion. If it is not clear from the data sheet, it is best to
measure the CM performance or just assume that it's 40dB worse than
the specified figure.
Note that it is seldom modeled in a (free) spice model.
This is a link to an extract discussing it's measurement.
https://1drv.ms/u/c/1af24d72a509cd48/ESErQT4Elb5FsgcgsOp1J3wBWZSYHvooHblQJPA3DmydbA?e=wwqtSy
What happens without the initial conditions? Does it take a long time to settle?
I'll be away until next week.
No idea. LTSpice is useless for handling large simulation data files
so I don't bother trying to use it to check for that sort of thing.
On 15/11/2024 7:56 pm, Bill Sloman wrote:
On 15/11/2024 3:14 am, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I finally got around to digging out my AD734 based Wein bridge simulation, and created a FET based version.
It's got a nasty 163kHz generator embedded in it somewhere, and I've put in an RL filter to keep that under control.
It looks as if the 163kHz was coming from the LTC6655-1.25V precision reference.
Putting in 4.7uF at C10 - rather than the 1.0uF I started off with - seems to make the simulation run a lot faster - about 20
times faster - and cleaned out the visible hash coming from the voltage reference.
The data sheet says use something between 2.7uF and 100uF and recommends film parts - ESR less than 0.1R. They don't like ceramic
parts.
Pulling out the LCR filter (L5,L6, C19, C20, R22 and R23) may have speeded up the simulation too.
The 2kHz and 3kHz harmonics aren't as good as they were - only about 65db below the fundamental - so Ill have to do some more
digging.
--
Bill Sloman, Sydney
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I've taken John May seriously, and reworked my phase shift oscillator to use three op amps, all with their non-inverting inputs
tied to ground.
The results aren't all that impressive, the lower harmonics are about 65dB below the fundamental. Start-up is slow - it takes
about five seconds of simulation before the circuit settles down into steady state operation, and that after I dropped the
integrating capacitor from 6.8uF to 680nF. The nice thing about the circuit is that I can explain what each bit is doing. I can
see a few tweaks that might be worth trying.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I've taken John May seriously, and reworked my phase shift oscillator to use three op amps, all with their non-inverting inputs
tied to ground.
The results aren't all that impressive, the lower harmonics are about 65dB below the fundamental. Start-up is slow - it takes
about five seconds of simulation before the circuit settles down into steady state operation, and that after I dropped the
integrating capacitor from 6.8uF to 680nF. The nice thing about the circuit is that I can explain what each bit is doing. I can
see a few tweaks that might be worth trying.
The simulation died after 3 seconds, as if insufficient gain to sustain oscillation.
You seem to have a lot of components.
Are you sure you really need all those ferrites?
Here's my really definitely final final offering.
A comfortable 90dB down at 2kHz and > 100 dB elsewhere.
Also looks clean either side of 1kHz.
Whether or not this has anything to do with reality I do not know.
The diode stabilizer string will be temperature dependent,
requiring readjustment of R4 and a total of three adjustments are needed. Only three op amps (two packages) are needed.
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I've taken John May seriously, and reworked my phase shift oscillator to use three op amps, all with their non-inverting inputs
tied to ground.
The results aren't all that impressive, the lower harmonics are about 65dB below the fundamental. Start-up is slow - it takes
about five seconds of simulation before the circuit settles down into steady state operation, and that after I dropped the
integrating capacitor from 6.8uF to 680nF. The nice thing about the circuit is that I can explain what each bit is doing. I can
see a few tweaks that might be worth trying.
The simulation died after 3 seconds, as if insufficient gain to sustain oscillation.
The circuit starts off by reducing gain. I think I can do something about that.
You seem to have a lot of components.
But I know what they all do.
Are you sure you really need all those ferrites?
No, but they are cheap, and op amps injecting hash into the power rails are never a good idea. Power supply rejection drops with
frequency, and U1 in particular pulls spikes of current from the power rails twice per cycle.
Here's my really definitely final final offering.
A comfortable 90dB down at 2kHz and > 100 dB elsewhere.
Also looks clean either side of 1kHz.
Whether or not this has anything to do with reality I do not know.
The diode stabilizer string will be temperature dependent,
requiring readjustment of R4 and a total of three adjustments are needed. >>> Only three op amps (two packages) are needed.
I'll take a look at it.
Simulate for 350 seconds? Don't collect data for the first 50 seconds?
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
__
Bill Sloman, Sydney
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I've taken John May seriously, and reworked my phase shift oscillator
to use three op amps, all with their non-inverting inputs
tied to ground.
The results aren't all that impressive, the lower harmonics are about
65dB below the fundamental. Start-up is slow - it takes
about five seconds of simulation before the circuit settles down into
steady state operation, and that after I dropped the
integrating capacitor from 6.8uF to 680nF. The nice thing about the
circuit is that I can explain what each bit is doing. I can
see a few tweaks that might be worth trying.
The simulation died after 3 seconds, as if insufficient gain to
sustain oscillation.
The circuit starts off by reducing gain. I think I can do something
about that.
You seem to have a lot of components.
But I know what they all do.
Are you sure you really need all those ferrites?
No, but they are cheap, and op amps injecting hash into the power rails
are never a good idea. Power supply rejection drops with frequency, and
U1 in particular pulls spikes of current from the power rails twice per cycle.
Here's my really definitely final final offering.
A comfortable 90dB down at 2kHz and > 100 dB elsewhere.
Also looks clean either side of 1kHz.
Whether or not this has anything to do with reality I do not know.
The diode stabilizer string will be temperature dependent,
requiring readjustment of R4 and a total of three adjustments are needed.
Only three op amps (two packages) are needed.
I'll take a look at it.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development. >>
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many components?
My circuit has far fewer components than yours.
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
This is the simplest circuit I can come up with.
Harmonics are more than 80dB down in simulation.
FFT the last 30 seconds.
There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
on exactly how much output is selected for the FFT. You may see different results.
If a prototype is ever built, attention to the type and quality of the capacitors used will be needed.
Electrolytics are not intended. Put C1 and C2 near U1 supply pins.
Also pay attention to the stability of +/- 6V.
It would be nice to have a single 12V rail version but so far I can't get it to work.
R1 and R2 and probably R7 should be easily changeable.
R3 should be 220 ohm ten turn. R9 should be 1M ohm ten turn in series with 470k.
I don't fully understand why the DC stabilization circuit through U2B achieves what it does
and this makes me concerned about whether a real circuit would have the same behaviour.
It was added when I noticed that the diodes D1 and D2 weren't contributing equally so I
decided to try to derive a DC correction signal. This was originally connected to the FET source
and then to R13. Since this is a DC correction signal I decided to try out the effect of
connecting it to U1 Vocm and was amazed that this works as well as it does. >>>>If you disconnect R5, harmonics will not be more than 50dB down because D1 and D2 are no
longer providing stable and equal contributions to the level control feedback.
If you need even better performance then the circuit referenced by Bill Sloman can be used.
https://www.google.com/search?q=AN132+purity
NSL-32SR3 is not expensive and simulation models exist but LT1468 is expensive.
Other references
https://www.google.com/search?&q=The+field+effect+transistor+as+a+voltage+controlled+resistor
https://www.google.com/search?&q=sine+wave+oscillator&udm=2
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SYMBOL schottky 640 480 M0
WINDOW 3 49 -26 VRight 2
WINDOW 0 -21 4 Left 2
SYMATTR Value BAS40HY
SYMATTR InstName D4
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 528 640 M0
WINDOW 3 25 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R16
SYMBOL res 720 640 M0
WINDOW 3 27 87 Left 2
SYMATTR Value 220k
SYMATTR InstName R17
SYMBOL res -112 -256 R0
WINDOW 0 38 42 Left 2
WINDOW 3 36 66 Left 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 320 -384 R0
WINDOW 0 -55 41 Left 2
WINDOW 3 -64 83 Left 2
SYMATTR InstName R13
SYMATTR Value 220k
SYMBOL res 448 -32 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R9
SYMATTR Value 1.0469Meg
SYMBOL res -80 -288 R180
WINDOW 0 40 70 Left 2
WINDOW 3 45 42 Left 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res -32 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 33k
SYMBOL res 176 464 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 220
SYMBOL res 16 592 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL cap 176 352 R180
WINDOW 0 -37 41 Left 2
WINDOW 3 -88 16 Left 2
SYMATTR InstName C7
SYMATTR Value 0.015
SYMATTR SpiceLine V=16 Irms=271m Rser=0.594318 Lser=0 mfg="KEMET" pn="C0603C153K4RAC" type="X7R"
SYMBOL OpAmps\\LT1057 -32 -496 M0
WINDOW 0 -63 128 Left 2
WINDOW 3 -54 156 Left 2
SYMATTR InstName U2A
SYMBOL cap 720 128 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 1
SYMATTR SpiceLine V=10 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM153R61A105ME95" type="X5R"
SYMBOL res 832 224 R0
SYMATTR InstName R18
SYMATTR Value 100k
SYMBOL res 32 -384 R0
SYMATTR InstName R6
SYMATTR Value 22k
SYMBOL res 192 -400 R270
WINDOW 0 35 55 VTop 2
WINDOW 3 -6 55 VBottom 2
SYMATTR InstName R12
SYMATTR Value 220k
SYMBOL res -80 -560 R270
WINDOW 0 31 55 VTop 2
WINDOW 3 -3 56 VBottom 2
SYMATTR InstName R4
SYMATTR Value 47k
SYMBOL cap 176 -352 M0
WINDOW 0 -22 9 Left 2
WINDOW 3 -31 54 Left 2
SYMATTR InstName C6
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 -352 M0
WINDOW 0 -36 9 Left 2
WINDOW 3 -31 54 Left 2
SYMATTR InstName C10
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 368 496 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C9
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 416 672 R0
WINDOW 0 -37 6 Left 2
WINDOW 3 -31 54 Left 2
SYMATTR InstName C11
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 608 672 R0
WINDOW 0 -33 9 Left 2
WINDOW 3 -31 54 Left 2
SYMATTR InstName C12
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 160 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -31 54 Left 2
SYMATTR InstName C1
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -192 432 R0
WINDOW 0 -22 9 Left 2
WINDOW 3 -31 54 Left 2
SYMATTR InstName C2
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap 32 224 R180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C4
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL diode -32 720 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL cap 0 -688 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 10
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60J106ME15" type="X5R"
SYMBOL cap -16 720 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C5
SYMATTR Value 1
SYMATTR SpiceLine V=10 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM153R61A105ME95" type="X5R"
TEXT -624 272 Left 2 !.tran 0 300s 0s startup
TEXT -1568 -728 Left 2 ;Edward Rawde's high purity 1kHz sinewave oscillator. 8 Nov 2024\n \nHarmonics are more than 80dB down in
simulation.\nFFT the last 30 seconds.\nThere is only one harmonic stopping me claiming 90dB but the exact FFT result can
depend\non
exactly how much output is selected for the FFT. You may see different results.\n \nIf a prototype is ever built, pay attention to
the type and quality of the capacitors used.\nElectrolytics are not intended. Put C1 and C2 near U1 supply pins.\nAlso pay
attention
to the stability of +/- 6V.\nIt would be nice to have a single 12V rail version but so far I can't get it to work.\n \nR1 and R2
and
probably R7 should be easily changeable.\nR3 should be 220 ohm ten turn. R9 should be 1M ohm ten turn in series with 470k.\n \nI
don't fully understand why the DC stabilization circuit through U2B achieves what it does\nand this makes me concerned about
whether
a real circuit would have the same behaviour.\nIt was added when I noticed that the diodes D1 and D2 weren't contributing equally
so
I \ndecided to try to derive a DC correction signal. This was originally connected to the FET source\nand then to R13. Since this
is
a DC correction signal I decided to try out the effect of\nconnecting it to U1 Vocm and was amazed that this works as well as it
does. \nIf you disconnect R5, harmonics will not be more than 50dB down because D1 and D2 are no\nlonger providing stable and
equal
contributions to the level control feedback.\n \nIf you need even better performance then the circuit referenced by Bill Sloman
can
be used.\nhttps://www.google.com/search?q=AN132+purity\nNSL-32SR3 is not expensive and simulation models exist but LT1468 is
expensive.\n \nOther references\n >>>>\nhttps://www.google.com/search?&q=The+field+effect+transistor+as+a+voltage+controlled+resistor\n
\nhttps://www.google.com/search?&q=sine+wave+oscillator&udm=2
Using an NSL-32SR3 doesn't really gain you anything over a FET. If
you keep |vds| much less than |Vt-vgs| in the circuit and compensate
for the vds/2 variation on the gate drive the distortion levels
produced will be lower than almost all opamps out there. Here's a
link to a sim using an LDR.
https://1drv.ms/f/c/1af24d72a509cd48/EkjNCaVyTfIggBrrAQAAAAABHXNKs52BoVHi7zaxKmdMMQ?e=oVD0JS
I've added some 3rd harmonic distortion to a linear model to give
distortion figures roughly in the ballpark of Fig 6 in the attached
application note (for small signal swings across the device). In the
oscillator o/p the 3rd is about 150dB down. If you use the linear LDR
model, or a FET, it will be much the same. (The opamps used in the sim
actually have distortions specs of about 130dB in reallity.)
Thanks for that. I left it overnight for 100 seconds of simulation. It looks like it has better harmonic performance than my
circuit.
Why use two op amps in the oscillator instead of one like my circuit?
Because of common mode (non)linearity. In most op-amps (especially
older designs) the distortion generated by the common mode signal is >typically one to two orders of magnitude larger than the transfer
distortion. If it is not clear from the data sheet, it is best to
measure the CM performance or just assume that it's 40dB worse than
the specified figure.
On Sun, 17 Nov 2024 02:01:25 +0000, JM
<sunaecoNoChoppedPork@gmail.com> wrote:
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"<snnnniiiiiipppp>
<invalid@invalid.invalid> wrote:
Because of common mode (non)linearity. In most op-amps (especially
older designs) the distortion generated by the common mode signal is
typically one to two orders of magnitude larger than the transfer
distortion. If it is not clear from the data sheet, it is best to
measure the CM performance or just assume that it's 40dB worse than
the specified figure.
To quote Jim Williams, "always invert."
Just the ESD diodes are a distortion hazard. I've seen people
bootstrap the power supplies to improve CMRR.
On Tue, 19 Nov 2024 20:59:04 -0500, "Edward Rawde"..
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
I've taken John May seriously, and reworked my phase shift oscillator to use three op amps, all with their non-inverting inputs
tied to ground.
The results aren't all that impressive, the lower harmonics are about 65dB below the fundamental. Start-up is slow - it takes
about five seconds of simulation before the circuit settles down into steady state operation, and that after I dropped the
integrating capacitor from 6.8uF to 680nF. The nice thing about the circuit is that I can explain what each bit is doing. I can
see a few tweaks that might be worth trying.
The simulation died after 3 seconds, as if insufficient gain to sustain oscillation.
You seem to have a lot of components.
Are you sure you really need all those ferrites?
Here's my really definitely final final offering.
A comfortable 90dB down at 2kHz and > 100 dB elsewhere.
Also looks clean either side of 1kHz.
Whether or not this has anything to do with reality I do not know.
The diode stabilizer string will be temperature dependent,
requiring readjustment of R4 and a total of three adjustments are needed. >>Only three op amps (two packages) are needed.
Thats a pretty unusual circuit. Was the original intent to create a
balanced output?
If you're trying to measure harmonics at a low level with ltspice you
need to set it up correctly. You need to turn off the raw file
compression (plotwinsize=0 option) and make sure the data is not
stored as single precision (the default) by setting option numdgt > 6.
Your also need to set the maximum timestep to something in the region
of 1/1000 (or 1/2000) of the fundamental period. If there's
convergence issues you might try setting vntol=1e-12 and reltol=1e-6,
and possibly setting itl2-4 to about 1000.
I tried your circuit with the dc servo removed (it was just
complicating things) and changed the fet control a little. The fet
your using isn't a great choice - look for something with a large
pinchoff voltage and a large idss, and jig things so that it operates
with vgs close to zero and with very little voltage swing across it.
As it was you were operating it pretty much at pinchoff.
You dont need to run your sims for long as some others have said. A
few cycles is all you need.
See if the attached runs for you. When
doing the fft use a blackman-harris window, H2,H3 should be about -120,-150dBc.
You should test the LT1944 in isolation as it may not
model distortion at all (most LT spice models are works of fiction).
There is an option in ltspice to stop it turning U's into mu.
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:rdtqjj9cbj8od0a7p4e99jfa2nsgf663r0@4ax.com...Increasing R1 and R2 to 100k seems to fix the 2kHz harmonic problem.
On Tue, 19 Nov 2024 20:59:04 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a
common mode problem, so why are you using an op amp designed
to deal with one?
This is sci.electronics.design not
sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V
reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so
then why are you using a circuit with so many components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the
gain around the three-amplifier ring tweaks both amplitude and frequency
- with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from
frequency. My copy of Williams and Taylor on electronic filter design
may get perused again.
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp
designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the gain around the three-amplifier ring tweaks both amplitude
and frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from frequency. My copy of Williams and Taylor on electronic filter
design may get perused again.
I found a simpler solution - copy the relevant arrangement in John May's circuit. It did work - after a fashion - but as I got
closer to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try to go the through the schematic to find and purge them. But the
last few passes haven't shown up anything. Frustrating. My father's advice in similar situautions was to "drop it in drawer for
six months, then take another look". It has worked in the past.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp
designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the gain around the three-amplifier ring tweaks both amplitude
and frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from frequency. My copy of Williams and Taylor on electronic filter
design may get perused again.
I found a simpler solution - copy the relevant arrangement in John May's circuit. It did work - after a fashion - but as I got
closer to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try to go the through the schematic to find and purge them. But the
last few passes haven't shown up anything. Frustrating. My father's advice in similar situautions was to "drop it in drawer for
six months, then take another look". It has worked in the past.
I also found a simpler solution. Taking on board advice from JM and others.
The circuit below does 0dB into 600 ohms and it only takes about 20 minutes to complete the simulation on my computer.
When it's done, select a sample of about 1 second near the end and FFT. Select Use current zoom extent and Blackman-Harris window.
It will say all harmonics are more than 120dB down.
I'm not saying this level of performance is achievable or measurable in reality so I don't see any point simulating further.
The actual distortion in reality will likely be that of the op amps so choose the lowest distortion op amp you can find.
Oh and if you need to know the exact function of any of the 21 components in this circuit just ask.
I'd feel embarrassed to have produced a circuit using over 70 components which only claims 65dB down on harmonics.
Does anyone know how to change the default trace in LTSpice?
When I click Run/pause it shows the wrong node so then I have to Delete This Trace and click output.
How do I make it default to output?
"Bill Sloman" <bill.sloman@ieee.org> wrote in messagenews:vhp713$12bnt$2@dont-email.me...
have a common mode problem, so why are you using an op ampOn 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't
so then why are you using a circuit with so many components?designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if
the gain around the three-amplifier ring tweaks both amplitudeMy circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking
frequency. My copy of Williams and Taylor on electronic filterand frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from
May's circuit. It did work - after a fashion - but as I gotdesign may get perused again.
I found a simpler solution - copy the relevant arrangement in John
to go the through the schematic to find and purge them. But thecloser to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try
advice in similar situautions was to "drop it in drawer forlast few passes haven't shown up anything. Frustrating. My father's
six months, then take another look". It has worked in the past.
I also found a simpler solution. Taking on board advice from JM andothers.
The circuit below does 0dB into 600 ohms and it only takes about 20minutes to complete the simulation on my computer.
When it's done, select a sample of about 1 second near the end and FFT. Select Use current zoom extent and Blackman-Harris window.in reality so I don't see any point simulating further.
It will say all harmonics are more than 120dB down.
I'm not saying this level of performance is achievable or measurable
The actual distortion in reality will likely be that of the op ampsso choose the lowest distortion op amp you can find.
Oh and if you need to know the exact function of any of the 21components in this circuit just ask.
I'd feel embarrassed to have produced a circuit using over 70components which only claims 65dB down on harmonics.
Does anyone know how to change the default trace in LTSpice?
When I click Run/pause it shows the wrong node so then I have toDelete This Trace and click output.
How do I make it default to output?
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp
designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many
components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the gain around the three-amplifier ring tweaks both
amplitude
and frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from frequency. My copy of Williams and Taylor on electronic filter
design may get perused again.
I found a simpler solution - copy the relevant arrangement in John May's circuit. It did work - after a fashion - but as I got
closer to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try to go the through the schematic to find and purge them. But
the
last few passes haven't shown up anything. Frustrating. My father's advice in similar situautions was to "drop it in drawer for
six months, then take another look". It has worked in the past.
I found that adding a couple of 14nmH ferrite beads around the transistors and the FETs stopped the simulation dropping out after
getting stuck on a too-short time step.
The current version isn't simulating all that fast - I let it run over-night and the amplitude control feed back loop turned out
to have been underdamped to the point of instability - it kept on hitting the rails and overshooting back into them. The current
version - with more damping - is now on it's second millisecond.
I also found a simpler solution. Taking on board advice from JM and others. >>
The circuit below does 0dB into 600 ohms and it only takes about 20 minutes to complete the simulation on my computer.
When it's done, select a sample of about 1 second near the end and FFT.
Select Use current zoom extent and Blackman-Harris window.
It will say all harmonics are more than 120dB down.
I'm not saying this level of performance is achievable or measurable in reality so I don't see any point simulating further.
The actual distortion in reality will likely be that of the op amps so choose the lowest distortion op amp you can find.
Oh and if you need to know the exact function of any of the 21 components in this circuit just ask.
I'd feel embarrassed to have produced a circuit using over 70 components which only claims 65dB down on harmonics.
Of course you would. The point of producing the circuit is to find out what it can do, and change it to make it work better. That
way you get to understand what the circuit is doing and why it is doing it, which isn't your strong point.
Does anyone know how to change the default trace in LTSpice?
There isn't one in the version I downloaded. When I start a simulation I get offered a blank display, and have to select a trace
to be displayed before I can see anything.
When I click Run/pause it shows the wrong node so then I have to Delete This Trace and click output.
How do I make it default to output?
Beats me.
--
Bill Sloman, Sydney
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp
designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many
components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the gain around the three-amplifier ring tweaks both
amplitude
and frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from frequency. My copy of Williams and Taylor on electronic filter
design may get perused again.
I found a simpler solution - copy the relevant arrangement in John May's circuit. It did work - after a fashion - but as I got
closer to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try to go the through the schematic to find and purge them. But
the
last few passes haven't shown up anything. Frustrating. My father's advice in similar situautions was to "drop it in drawer for
six months, then take another look". It has worked in the past.
I found that adding a couple of 14nmH ferrite beads around the transistors and the FETs stopped the simulation dropping out after
getting stuck on a too-short time step.
The current version isn't simulating all that fast - I let it run over-night and the amplitude control feed back loop turned out
to have been underdamped to the point of instability - it kept on hitting the rails and overshooting back into them. The current
version - with more damping - is now on it's second millisecond.
I also found a simpler solution. Taking on board advice from JM and others. >>
The circuit below does 0dB into 600 ohms and it only takes about 20 minutes to complete the simulation on my computer.
When it's done, select a sample of about 1 second near the end and FFT.
Select Use current zoom extent and Blackman-Harris window.
It will say all harmonics are more than 120dB down.
I'm not saying this level of performance is achievable or measurable in reality so I don't see any point simulating further.
The actual distortion in reality will likely be that of the op amps so choose the lowest distortion op amp you can find.
Oh and if you need to know the exact function of any of the 21 components in this circuit just ask.
I'd feel embarrassed to have produced a circuit using over 70 components which only claims 65dB down on harmonics.
Of course you would. The point of producing the circuit is to find out what it can do, and change it to make it work better. That
way you get to understand what the circuit is doing and why it is doing it, which isn't your strong point.
Does anyone know how to change the default trace in LTSpice?
There isn't one in the version I downloaded. When I start a simulation I get offered a blank display, and have to select a trace
to be displayed before I can see anything.
When I click Run/pause it shows the wrong node so then I have to Delete This Trace and click output.
How do I make it default to output?
Beats me.
--
Bill Sloman, Sydney
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp
designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many
components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the gain around the three-amplifier ring tweaks both
amplitude
and frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from frequency. My copy of Williams and Taylor on electronic filter
design may get perused again.
I found a simpler solution - copy the relevant arrangement in John May's circuit. It did work - after a fashion - but as I got
closer to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try to go the through the schematic to find and purge them. But
the
last few passes haven't shown up anything. Frustrating. My father's advice in similar situautions was to "drop it in drawer for
six months, then take another look". It has worked in the past.
I found that adding a couple of 14nmH ferrite beads around the transistors and the FETs stopped the simulation dropping out after
getting stuck on a too-short time step.
The current version isn't simulating all that fast - I let it run over-night and the amplitude control feed back loop turned out
to have been underdamped to the point of instability - it kept on hitting the rails and overshooting back into them. The current
version - with more damping - is now on it's second millisecond.
Ok well when you've got a circuit which rivals the one I posted for harmonic distortion and component count let me know.
I also found a simpler solution. Taking on board advice from JM and others. >>>
The circuit below does 0dB into 600 ohms and it only takes about 20 minutes to complete the simulation on my computer.
When it's done, select a sample of about 1 second near the end and FFT.
Select Use current zoom extent and Blackman-Harris window.
It will say all harmonics are more than 120dB down.
I'm not saying this level of performance is achievable or measurable in reality so I don't see any point simulating further.
The actual distortion in reality will likely be that of the op amps so choose the lowest distortion op amp you can find.
Oh and if you need to know the exact function of any of the 21 components in this circuit just ask.
I'd feel embarrassed to have produced a circuit using over 70 components which only claims 65dB down on harmonics.
Of course you would. The point of producing the circuit is to find out what it can do, and change it to make it work better. That
way you get to understand what the circuit is doing and why it is doing it, which isn't your strong point.
Silly me. I thought that's what I'd been doing all along.
Does anyone know how to change the default trace in LTSpice?
There isn't one in the version I downloaded. When I start a simulation I get offered a blank display, and have to select a trace
to be displayed before I can see anything.
Same here. Therefore it has to be storing alternative behaviour in one of that files it creates.
I have since found that this is a plt file.
When I click Run/pause it shows the wrong node so then I have to Delete This Trace and click output.
How do I make it default to output?
Beats me.
It turns out that the solution to this problem is to delete the plt file. However I don't know exactly what the circumstances are for this file to be created.
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp
designed
to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with
more
precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many
components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the gain around the three-amplifier ring tweaks both
amplitude
and frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from frequency. My copy of Williams and Taylor on electronic filter
design may get perused again.
I found a simpler solution - copy the relevant arrangement in John May's circuit. It did work - after a fashion - but as I got
closer to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try to go the through the schematic to find and purge them. But
the
last few passes haven't shown up anything. Frustrating. My father's advice in similar situautions was to "drop it in drawer
for
six months, then take another look". It has worked in the past.
I found that adding a couple of 14nmH ferrite beads around the transistors and the FETs stopped the simulation dropping out
after
getting stuck on a too-short time step.
The current version isn't simulating all that fast - I let it run over-night and the amplitude control feed back loop turned out
to have been underdamped to the point of instability - it kept on hitting the rails and overshooting back into them. The current
version - with more damping - is now on it's second millisecond.
Ok well when you've got a circuit which rivals the one I posted for harmonic distortion and component count let me know.
Component count isn't all that important. If you can replace an expensive or hard to get component with a couple of cheap ones,
that's a win.
Alternative ways of doing much the same job are also interesting -
patent evasion used to be a popular sport. Once the patentable details are buried inside a programmable device it's less
worthwhile.
Lawyers don't like going into technical detail - RCA won a colour TV patent case against EMI in a US Court because the judges
couldn't be persuaded that quadrature modulation was exactly the same thing as sine/cosine modulation.
I also found a simpler solution. Taking on board advice from JM and others.
The circuit below does 0dB into 600 ohms and it only takes about 20 minutes to complete the simulation on my computer.
When it's done, select a sample of about 1 second near the end and FFT. >>>> Select Use current zoom extent and Blackman-Harris window.
It will say all harmonics are more than 120dB down.
I'm not saying this level of performance is achievable or measurable in reality so I don't see any point simulating further.
The actual distortion in reality will likely be that of the op amps so choose the lowest distortion op amp you can find.
Oh and if you need to know the exact function of any of the 21 components in this circuit just ask.
I'd feel embarrassed to have produced a circuit using over 70 components which only claims 65dB down on harmonics.
Of course you would. The point of producing the circuit is to find out what it can do, and change it to make it work better.
That
way you get to understand what the circuit is doing and why it is doing it, which isn't your strong point.
Silly me. I thought that's what I'd been doing all along.
Perhaps.
Does anyone know how to change the default trace in LTSpice?
There isn't one in the version I downloaded. When I start a simulation I get offered a blank display, and have to select a trace
to be displayed before I can see anything.
Same here. Therefore it has to be storing alternative behaviour in one of that files it creates.
I have since found that this is a plt file.
When I click Run/pause it shows the wrong node so then I have to Delete This Trace and click output.
How do I make it default to output?
Beats me.
It turns out that the solution to this problem is to delete the plt file.
However I don't know exactly what the circumstances are for this file to be created.
--
Bill Sloman, Sydney
<snip>"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhs1ea$1kbt4$1@dont-email.me...
Component count isn't all that important. If you can replace an expensive or hard to get component with a couple of cheap ones,
that's a win.
I've worked in plenty of places where using four times as many components as you could have used (and hence four times the cost)
would not be seen as a win.
On 24/11/2024 5:11 am, Edward Rawde wrote:...
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhs1ea$1kbt4$1@dont-email.me...
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde" >>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
I found that adding a couple of 14nmH ferrite beads around the transistors and the FETs stopped the simulation dropping out
after getting stuck on a too-short time step.
Additional components in the simulation that you could probably leave out of a real circuit. I've found another place to put a
ferrite bead which speeds up the simulation ever more, but it is till not all that quick.
The current version isn't simulating all that fast - I let it run over-night and the amplitude control feed back loop turned
out
to have been underdamped to the point of instability - it kept on hitting the rails and overshooting back into them. The
current
version - with more damping - is now on it's second millisecond.
Ok well when you've got a circuit which rivals the one I posted for harmonic distortion and component count let me know.
I'm not going to be constrained by that.
Component count isn't all that important. If you can replace an expensive or hard to get component with a couple of cheap ones,
that's a win.
I've worked in plenty of places where using four times as many components as you could have used (and hence four times the cost)
would not be seen as a win.
Four times the number of components isn't four times the cost, as I did point out. I got brownie points once for replacing a fifty
pence 25-turn trimming potentiometer with a more settable trimmer with the same footprint at five times the cost.
What we lost on the cost of the part we more than won back in a half-hour drop in setting up time. The original designer should
have put in coarse and fine pots, which would have been more parts, but still cheaper than my quick and dirty fix.
Alternative ways of doing much the same job are also interesting -
Sure. There are plenty of examples of that, such as make it a beam tetrode instead of a pentode.
patent evasion used to be a popular sport. Once the patentable details are buried inside a programmable device it's less
worthwhile.
Lawyers don't like going into technical detail - RCA won a colour TV patent case against EMI in a US Court because the judges
couldn't be persuaded that quadrature modulation was exactly the same thing as sine/cosine modulation.
Sony didn't care about the PAL patents. They just put a hue control on their early sets.
The EMI-RCA court battle preceded PAL versus NTSC. It was about how you added colour information on top of the original black and
white brightness signal.
<snip>
--
Bill Sloman, Sydney
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhs1ea$1kbt4$1@dont-email.me...
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde" >>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
<snip>
I've no idea why you are using the LT1994. The circuit doesn't have a common mode problem, so why are you using an op amp
designed to deal with one?
This is sci.electronics.design not sci.electronics.incremental-development.
And the six diode "stabiliser string" is nuts. If you need a 3.6V reference voltage there are lots of ways to do it with
more precision and better temperature stability.
In that case please show a circuit with better performance.
It may be that some of the circuits JM posted can do better but if so then why are you using a circuit with so many
components?
My circuit has far fewer components than yours.
But you don't seem to be able to tell us what they do.
I think I've found my conceptual problem with my circuit. Tweaking the gain around the three-amplifier ring tweaks both
amplitude
and frequency - with more gain a lower frequency signal can still propagate around the ring.
I've got to find a mechanism that will separate amplitude from frequency. My copy of Williams and Taylor on electronic filter
design may get perused again.
I found a simpler solution - copy the relevant arrangement in John May's circuit. It did work - after a fashion - but as I got
closer to getting it to a state where it could do what I wanted, the circuit got less and less willing to simulate.
I suspect an accumulation of typo's in component values - I do try to go the through the schematic to find and purge them. But
the last few passes haven't shown up anything. Frustrating. My father's advice in similar situautions was to "drop it in drawer
for six months, then take another look". It has worked in the past.
I found that adding a couple of 14nmH ferrite beads around the transistors and the FETs stopped the simulation dropping out
after getting stuck on a too-short time step.
The current version isn't simulating all that fast - I let it run over-night and the amplitude control feed back loop turned out
to have been underdamped to the point of instability - it kept on hitting the rails and overshooting back into them. The current
version - with more damping - is now on it's second millisecond.
Ok well when you've got a circuit which rivals the one I posted for harmonic distortion and component count let me know.
Component count isn't all that important. If you can replace an expensive or hard to get component with a couple of cheap ones,
that's a win.
I've worked in plenty of places where using four times as many components as you could have used (and hence four times the cost)
would not be seen as a win.
Alternative ways of doing much the same job are also interesting -
Sure. There are plenty of examples of that, such as make it a beam tetrode instead of a pentode.
patent evasion used to be a popular sport. Once the patentable details are buried inside a programmable device it's less
worthwhile.
Lawyers don't like going into technical detail - RCA won a colour TV patent case against EMI in a US Court because the judges
couldn't be persuaded that quadrature modulation was exactly the same thing as sine/cosine modulation.
Sony didn't care about the PAL patents. They just put a hue control on their early sets.
I also found a simpler solution. Taking on board advice from JM and others.
The circuit below does 0dB into 600 ohms and it only takes about 20 minutes to complete the simulation on my computer.
When it's done, select a sample of about 1 second near the end and FFT. >>>>> Select Use current zoom extent and Blackman-Harris window.
It will say all harmonics are more than 120dB down.
I'm not saying this level of performance is achievable or measurable in reality so I don't see any point simulating further.
The actual distortion in reality will likely be that of the op amps so choose the lowest distortion op amp you can find.
Oh and if you need to know the exact function of any of the 21 components in this circuit just ask.
I'd feel embarrassed to have produced a circuit using over 70 components which only claims 65dB down on harmonics.
Of course you would. The point of producing the circuit is to find out what it can do, and change it to make it work better.
That way you get to understand what the circuit is doing and why it is doing it, which isn't your strong point.
Silly me. I thought that's what I'd been doing all along.
Perhaps.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhue9h$243sl$1@dont-email.me...
On 24/11/2024 5:11 am, Edward Rawde wrote:...
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhs1ea$1kbt4$1@dont-email.me...
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde" >>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
I found that adding a couple of 14nmH ferrite beads around the transistors and the FETs stopped the simulation dropping out
after getting stuck on a too-short time step.
Additional components in the simulation that you could probably leave out of a real circuit. I've found another place to put a
ferrite bead which speeds up the simulation ever more, but it is till not all that quick.
The current version isn't simulating all that fast - I let it run over-night and the amplitude control feed back loop turned
out
to have been underdamped to the point of instability - it kept on hitting the rails and overshooting back into them. The
current
version - with more damping - is now on it's second millisecond.
Ok well when you've got a circuit which rivals the one I posted for harmonic distortion and component count let me know.
I'm not going to be constrained by that.
Ok I'll settle for matching the harmonic distortion level, even if you need 1000 components.
--
Bill Sloman, Sydney
On 24/11/2024 5:10 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhue9h$243sl$1@dont-email.me...
On 24/11/2024 5:11 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhs1ea$1kbt4$1@dont-email.me...
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message >>>>>>>>>>>>>> news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message >>>>>>>>>>>>>>>> news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com... >>>>>>>>>>>>>>>>> On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message >>>>>>>>>>>>>>>>>> news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com... >>>>>>>>>>>>>>>>>>> On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
On 25/11/2024 1:02 pm, Bill Sloman wrote:
On 24/11/2024 5:10 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhue9h$243sl$1@dont-email.me...
On 24/11/2024 5:11 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhs1ea$1kbt4$1@dont-email.me...
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
<snip>
The current version has been running overnight and has got to three seconds, and the DFT from 2.8 to three seconds shows third
harmonic about 90db below the fundamental. The noise floor is about 100dB down and the other harmonics are barely visible above
it.
Here's the .asc file. There are extra components put in to make it simulate faster - L1 and L14 are the obvious examples, but L10,
L11 and L12 got put in for the same reason. I suspect that if I had put in equivalent series resistance and inductance for C22 as
well as for C6 and C15 I might not have needed some of them.
There is some other tidying up I could do, and that should get get the simulation speed up. I got a new circuit from John May last
night, and it not only spits out a very clean sine wave but also simulated very fast. I forgot to put it on solid state disk
before I ran it, and it took as long to get one of the waveforms off the spinning hard disk as it had done to run the simulation.
Ny tidying up is going to wait until I've got ten seconds worth of simulation out of the current circuit, and can look at the
details of what's going on deep in the circuit
On Tue, 26 Nov 2024 15:32:38 +1100, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 25/11/2024 1:02 pm, Bill Sloman wrote:
On 24/11/2024 5:10 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhue9h$243sl$1@dont-email.me...
On 24/11/2024 5:11 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhs1ea$1kbt4$1@dont-email.me...
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message >>>>>>>>>>>>> news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message >>>>>>>>>>>>>>>> news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message >>>>>>>>>>>>>>>>>> news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com... >>>>>>>>>>>>>>>>>>> On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message >>>>>>>>>>>>>>>>>>>> news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com... >>>>>>>>>>>>>>>>>>>>> On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
<snip>
The current version has been running overnight and has got to three
seconds, and the DFT from 2.8 to three seconds shows third harmonic
about 90db below the fundamental. The noise floor is about 100dB down
and the other harmonics are barely visible above it.
Here's the .asc file. There are extra components put in to make it
simulate faster - L1 and L14 are the obvious examples, but L10, L11 and
L12 got put in for the same reason. I suspect that if I had put in
equivalent series resistance and inductance for C22 as well as for C6
and C15 I might not have needed some of them.
There is some other tidying up I could do, and that should get get the
simulation speed up. I got a new circuit from John May last night, and
it not only spits out a very clean sine wave but also simulated very
fast. I forgot to put it on solid state disk before I ran it, and it
took as long to get one of the waveforms off the spinning hard disk as
it had done to run the simulation.
When evaluating architecture there's little to be gained by using a complicated opamp model. Use a simple 1 or 2 pole model to begin
with.
Try the attached file, I've used a simple model to speed up the
simulation, and made a slight circuit change. This shows the
harmonics due to the control loop to be sub 130dBc. Of course the
amplifier harmonic distortion is not simulated, but neither was it in
the simulation by Mr Rawde.
On 27/11/2024 7:48 pm, JM wrote:...
On Tue, 26 Nov 2024 15:32:38 +1100, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 25/11/2024 1:02 pm, Bill Sloman wrote:
On 24/11/2024 5:10 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhue9h$243sl$1@dont-email.me...
On 24/11/2024 5:11 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhs1ea$1kbt4$1@dont-email.me...
On 23/11/2024 4:12 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhrma8$1io30$2@dont-email.me...
On 23/11/2024 3:32 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:vhp713$12bnt$2@dont-email.me...
On 21/11/2024 1:00 am, Bill Sloman wrote:
On 20/11/2024 2:03 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message >>>>>>>>>>>>>> news:vhjj2v$24eu4$3@dont-email.me...
On 20/11/2024 1:29 pm, Bill Sloman wrote:
On 20/11/2024 12:59 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message >>>>>>>>>>>>>>>>> news:vhibce$1t7v2$1@dont-email.me...
On 18/11/2024 2:58 pm, Edward Rawde wrote: >>>>>>>>>>>>>>>>>>> "JM" <sunaecoNoChoppedPork@gmail.com> wrote in message >>>>>>>>>>>>>>>>>>> news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com... >>>>>>>>>>>>>>>>>>>> On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message >>>>>>>>>>>>>>>>>>>>> news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com... >>>>>>>>>>>>>>>>>>>>>> On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde" >>>>>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
When evaluating architecture there's little to be gained by using a
complicated opamp model. Use a simple 1 or 2 pole model to begin
with.
Try the attached file, I've used a simple model to speed up the
simulation, and made a slight circuit change. This shows the
harmonics due to the control loop to be sub 130dBc. Of course the
amplifier harmonic distortion is not simulated, but neither was it in
the simulation by Mr Rawde.
Thanks for that. I've got it into a form that my copy of LTSpice recognises as a .asc file, so I have looked at it.
I haven't run it yet because I'm running yet another variant of the circuit, which has got to 2.4 seconds, and I'll leave it
running overnight.
I'm currently curious about the effect of the phase of the 2kHz component in the control signal (coming from my full-wave
rectifier), and a fast simulating version of the circuit is just what I need to get that sorted out. I had thought that that it
would be trivial to get the phase right, but my first attempt didn't get close.
I could go mad and put a version of the circuit into KiCad and create a printed circuit layout and get some Chinese firm to make
and load the board.
It would be an extravagance, but nothing dramatic.
--
Bill Sloman, Sydney
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