• Re: An actual circuit

    From john larkin@21:1/5 to invalid@invalid.invalid on Thu May 23 13:06:46 2024
    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of the >view that to make an LED flash you would need something to decide when it >should be on or off. So that would be some kind of software or digital >system.

    This reminded me of when, in my teen years, I was curious about how slow I >could make an LED flash without using any expensively large capacitors.

    I built a circuit like the one below but it needed a kick starter (another >resistor, larger capacitor and diode) to make it go at power on.

    LTSpice says the circuit below starts up with only a little imbalance in the >values of R2 and R6 but how can I be sure that a real circuit will do this >when component tolerances are taken into account?

    Watch out for line wraps and 0.1 uF character encoding issues.


    The jfet astable is cute.

    I had a high-voltage supply and wanted to blink an LED when there was potentially dangerous voltage. I used a Supertex depletion fet to
    charge a cap, and a diac to dump into the LED at about 1 Hz. Five
    parts, including the LED.




    Version 4
    SHEET 1 1396 772
    WIRE -144 -512 -384 -512
    WIRE -16 -512 -144 -512
    WIRE 496 -512 -16 -512
    WIRE 624 -512 496 -512
    WIRE -144 -432 -144 -512
    WIRE -16 -432 -16 -512
    WIRE 496 -432 496 -512
    WIRE 624 -432 624 -512
    WIRE -208 -272 -272 -272
    WIRE -144 -272 -144 -368
    WIRE -144 -272 -208 -272
    WIRE -16 -272 -16 -352
    WIRE 32 -272 -16 -272
    WIRE 64 -272 32 -272
    WIRE 176 -272 128 -272
    WIRE 352 -272 304 -272
    WIRE 448 -272 416 -272
    WIRE 496 -272 496 -352
    WIRE 496 -272 448 -272
    WIRE 624 -272 624 -368
    WIRE 688 -272 624 -272
    WIRE 752 -272 688 -272
    WIRE -384 -256 -384 -512
    WIRE -16 -192 -16 -272
    WIRE 496 -192 496 -272
    WIRE 96 -128 32 -128
    WIRE 176 -128 304 -272
    WIRE 176 -128 96 -128
    WIRE 304 -128 176 -272
    WIRE 384 -128 304 -128
    WIRE 448 -128 384 -128
    WIRE -144 -48 -144 -272
    WIRE 624 -48 624 -272
    WIRE -16 0 -16 -96
    WIRE -16 0 -80 0
    WIRE 496 0 496 -96
    WIRE 560 0 496 0
    WIRE 176 16 176 -128
    WIRE 304 16 304 -128
    WIRE -16 32 -16 0
    WIRE 496 32 496 0
    WIRE -144 96 -144 48
    WIRE 624 96 624 48
    WIRE -384 208 -384 -176
    WIRE -144 208 -144 176
    WIRE -144 208 -384 208
    WIRE -16 208 -16 112
    WIRE -16 208 -144 208
    WIRE 176 208 176 96
    WIRE 176 208 -16 208
    WIRE 304 208 304 96
    WIRE 304 208 176 208
    WIRE 496 208 496 112
    WIRE 496 208 304 208
    WIRE 624 208 624 176
    WIRE 624 208 496 208
    WIRE -384 240 -384 208
    FLAG 32 -272 leftd
    FLAG 448 -272 rightd
    FLAG 96 -128 leftg
    FLAG 384 -128 rightg
    FLAG -384 240 0
    FLAG -208 -272 leftled
    FLAG 688 -272 rightled
    SYMBOL njf 448 -192 R0
    WINDOW 0 0 -11 Left 2
    WINDOW 3 -59 98 Left 2
    SYMATTR InstName J1
    SYMATTR Value 2N3819
    SYMBOL njf 32 -192 M0
    WINDOW 0 7 -9 Left 2
    WINDOW 3 -64 100 Left 2
    SYMATTR InstName J2
    SYMATTR Value 2N3819
    SYMBOL npn 560 -48 R0
    WINDOW 0 61 31 Left 2
    WINDOW 3 61 69 Left 2
    SYMATTR InstName Q2
    SYMATTR Value 2N3904
    SYMBOL res -32 -448 R0
    SYMATTR InstName R2
    SYMATTR Value 2.7k
    SYMBOL res 480 -448 R0
    SYMATTR InstName R6
    SYMATTR Value 3.3k
    SYMBOL voltage -384 -272 R0
    WINDOW 123 0 0 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR InstName V1
    SYMATTR Value 12
    SYMBOL cap 64 -256 R270
    WINDOW 0 32 32 VTop 2
    WINDOW 3 0 32 VBottom 2
    SYMATTR InstName C2
    SYMATTR Value 0.1µ
    SYMATTR SpiceLine V=25 Irms=0 Rser=0.0173 Lser=350p mfg="Würth Elektronik" >pn="885012207072 WCAP-CSGP 0805" type="X7R"
    SYMBOL res 480 16 R0
    SYMATTR InstName R7
    SYMATTR Value 1k
    SYMBOL npn -80 -48 M0
    WINDOW 0 57 22 Left 2
    WINDOW 3 55 56 Left 2
    SYMATTR InstName Q3
    SYMATTR Value 2N3904
    SYMBOL res -32 16 R0
    SYMATTR InstName R3
    SYMATTR Value 1k
    SYMBOL res 160 0 R0
    SYMATTR InstName R4
    SYMATTR Value 10Meg
    SYMBOL res 288 0 R0
    SYMATTR InstName R5
    SYMATTR Value 10Meg
    SYMBOL res 608 80 R0
    SYMATTR InstName R8
    SYMATTR Value 150
    SYMBOL res -160 80 R0
    SYMATTR InstName R1
    SYMATTR Value 150
    SYMBOL LED 608 -432 R0
    WINDOW 0 31 -3 Left 2
    WINDOW 3 33 77 Left 2
    SYMATTR InstName D7
    SYMATTR Value NSCW100
    SYMBOL LED -160 -432 R0
    WINDOW 0 -32 3 Left 2
    WINDOW 3 -113 67 Left 2
    SYMATTR InstName D6
    SYMATTR Value NSCW100
    SYMBOL cap 352 -256 R270
    WINDOW 0 32 32 VTop 2
    WINDOW 3 0 32 VBottom 2
    SYMATTR InstName C3
    SYMATTR Value 0.1µ
    SYMATTR SpiceLine V=25 Irms=0 Rser=0.0173 Lser=350p mfg="Würth Elektronik" >pn="885012207072 WCAP-CSGP 0805" type="X7R"
    TEXT -344 240 Left 2 !.tran 1000


    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to All on Thu May 23 15:35:00 2024
    I was having a conversation with a younger person who seemed to be of the
    view that to make an LED flash you would need something to decide when it should be on or off. So that would be some kind of software or digital
    system.

    This reminded me of when, in my teen years, I was curious about how slow I could make an LED flash without using any expensively large capacitors.

    I built a circuit like the one below but it needed a kick starter (another resistor, larger capacitor and diode) to make it go at power on.

    LTSpice says the circuit below starts up with only a little imbalance in the values of R2 and R6 but how can I be sure that a real circuit will do this
    when component tolerances are taken into account?

    Watch out for line wraps and 0.1 uF character encoding issues.

    Version 4
    SHEET 1 1396 772
    WIRE -144 -512 -384 -512
    WIRE -16 -512 -144 -512
    WIRE 496 -512 -16 -512
    WIRE 624 -512 496 -512
    WIRE -144 -432 -144 -512
    WIRE -16 -432 -16 -512
    WIRE 496 -432 496 -512
    WIRE 624 -432 624 -512
    WIRE -208 -272 -272 -272
    WIRE -144 -272 -144 -368
    WIRE -144 -272 -208 -272
    WIRE -16 -272 -16 -352
    WIRE 32 -272 -16 -272
    WIRE 64 -272 32 -272
    WIRE 176 -272 128 -272
    WIRE 352 -272 304 -272
    WIRE 448 -272 416 -272
    WIRE 496 -272 496 -352
    WIRE 496 -272 448 -272
    WIRE 624 -272 624 -368
    WIRE 688 -272 624 -272
    WIRE 752 -272 688 -272
    WIRE -384 -256 -384 -512
    WIRE -16 -192 -16 -272
    WIRE 496 -192 496 -272
    WIRE 96 -128 32 -128
    WIRE 176 -128 304 -272
    WIRE 176 -128 96 -128
    WIRE 304 -128 176 -272
    WIRE 384 -128 304 -128
    WIRE 448 -128 384 -128
    WIRE -144 -48 -144 -272
    WIRE 624 -48 624 -272
    WIRE -16 0 -16 -96
    WIRE -16 0 -80 0
    WIRE 496 0 496 -96
    WIRE 560 0 496 0
    WIRE 176 16 176 -128
    WIRE 304 16 304 -128
    WIRE -16 32 -16 0
    WIRE 496 32 496 0
    WIRE -144 96 -144 48
    WIRE 624 96 624 48
    WIRE -384 208 -384 -176
    WIRE -144 208 -144 176
    WIRE -144 208 -384 208
    WIRE -16 208 -16 112
    WIRE -16 208 -144 208
    WIRE 176 208 176 96
    WIRE 176 208 -16 208
    WIRE 304 208 304 96
    WIRE 304 208 176 208
    WIRE 496 208 496 112
    WIRE 496 208 304 208
    WIRE 624 208 624 176
    WIRE 624 208 496 208
    WIRE -384 240 -384 208
    FLAG 32 -272 leftd
    FLAG 448 -272 rightd
    FLAG 96 -128 leftg
    FLAG 384 -128 rightg
    FLAG -384 240 0
    FLAG -208 -272 leftled
    FLAG 688 -272 rightled
    SYMBOL njf 448 -192 R0
    WINDOW 0 0 -11 Left 2
    WINDOW 3 -59 98 Left 2
    SYMATTR InstName J1
    SYMATTR Value 2N3819
    SYMBOL njf 32 -192 M0
    WINDOW 0 7 -9 Left 2
    WINDOW 3 -64 100 Left 2
    SYMATTR InstName J2
    SYMATTR Value 2N3819
    SYMBOL npn 560 -48 R0
    WINDOW 0 61 31 Left 2
    WINDOW 3 61 69 Left 2
    SYMATTR InstName Q2
    SYMATTR Value 2N3904
    SYMBOL res -32 -448 R0
    SYMATTR InstName R2
    SYMATTR Value 2.7k
    SYMBOL res 480 -448 R0
    SYMATTR InstName R6
    SYMATTR Value 3.3k
    SYMBOL voltage -384 -272 R0
    WINDOW 123 0 0 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR InstName V1
    SYMATTR Value 12
    SYMBOL cap 64 -256 R270
    WINDOW 0 32 32 VTop 2
    WINDOW 3 0 32 VBottom 2
    SYMATTR InstName C2
    SYMATTR Value 0.1µ
    SYMATTR SpiceLine V=25 Irms=0 Rser=0.0173 Lser=350p mfg="Würth Elektronik" pn="885012207072 WCAP-CSGP 0805" type="X7R"
    SYMBOL res 480 16 R0
    SYMATTR InstName R7
    SYMATTR Value 1k
    SYMBOL npn -80 -48 M0
    WINDOW 0 57 22 Left 2
    WINDOW 3 55 56 Left 2
    SYMATTR InstName Q3
    SYMATTR Value 2N3904
    SYMBOL res -32 16 R0
    SYMATTR InstName R3
    SYMATTR Value 1k
    SYMBOL res 160 0 R0
    SYMATTR InstName R4
    SYMATTR Value 10Meg
    SYMBOL res 288 0 R0
    SYMATTR InstName R5
    SYMATTR Value 10Meg
    SYMBOL res 608 80 R0
    SYMATTR InstName R8
    SYMATTR Value 150
    SYMBOL res -160 80 R0
    SYMATTR InstName R1
    SYMATTR Value 150
    SYMBOL LED 608 -432 R0
    WINDOW 0 31 -3 Left 2
    WINDOW 3 33 77 Left 2
    SYMATTR InstName D7
    SYMATTR Value NSCW100
    SYMBOL LED -160 -432 R0
    WINDOW 0 -32 3 Left 2
    WINDOW 3 -113 67 Left 2
    SYMATTR InstName D6
    SYMATTR Value NSCW100
    SYMBOL cap 352 -256 R270
    WINDOW 0 32 32 VTop 2
    WINDOW 3 0 32 VBottom 2
    SYMATTR InstName C3
    SYMATTR Value 0.1µ
    SYMATTR SpiceLine V=25 Irms=0 Rser=0.0173 Lser=350p mfg="Würth Elektronik" pn="885012207072 WCAP-CSGP 0805" type="X7R"
    TEXT -344 240 Left 2 !.tran 1000

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to john larkin on Fri May 24 07:38:12 2024
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of the >>view that to make an LED flash you would need something to decide when it >>should be on or off. So that would be some kind of software or digital >>system.

    This reminded me of when, in my teen years, I was curious about how slow I >>could make an LED flash without using any expensively large capacitors.

    I built a circuit like the one below but it needed a kick starter (another >>resistor, larger capacitor and diode) to make it go at power on.

    LTSpice says the circuit below starts up with only a little imbalance in the >>values of R2 and R6 but how can I be sure that a real circuit will do this >>when component tolerances are taken into account?

    Watch out for line wraps and 0.1 uF character encoding issues.


    The jfet astable is cute.

    I had a high-voltage supply and wanted to blink an LED when there was >potentially dangerous voltage. I used a Supertex depletion fet to
    charge a cap, and a diac to dump into the LED at about 1 Hz. Five
    parts, including the LED.



    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to john larkin on Fri May 24 11:59:31 2024
    "john larkin" <jl@650pot.com> wrote in message news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde" >><invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of the >>>view that to make an LED flash you would need something to decide when it >>>should be on or off. So that would be some kind of software or digital >>>system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart capacitor.
    So I had a complicated circuit with two more diodes and a transistor in the hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it could start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into operation after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 is 3.3k?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to invalid@invalid.invalid on Fri May 24 10:55:26 2024
    On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message >news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde" >>><invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of the >>>>view that to make an LED flash you would need something to decide when it >>>>should be on or off. So that would be some kind of software or digital >>>>system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart >capacitor.
    So I had a complicated circuit with two more diodes and a transistor in the >hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it could >start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into operation >after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 is >3.3k?


    Yes, it is mysterious. Set both drain resistors to 3.3K and zoom way
    up on the two source voltages for the first 20 seconds.

    LT Spice may have some hidden asymmetry. It has to do math
    sequentially, maybe.

    In real life, parts will be plenty asymmetric. Especially jfets.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to john larkin on Fri May 24 14:00:06 2024
    On 5/24/2024 1:55 PM, john larkin wrote:
    On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of the >>>>> view that to make an LED flash you would need something to decide when it >>>>> should be on or off. So that would be some kind of software or digital >>>>> system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor in the >> hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it could >> start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into operation >> after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 is >> 3.3k?


    Yes, it is mysterious. Set both drain resistors to 3.3K and zoom way
    up on the two source voltages for the first 20 seconds.

    LT Spice may have some hidden asymmetry. It has to do math
    sequentially, maybe.

    In real life, parts will be plenty asymmetric. Especially jfets.


    There are bunch of variants of this circuit, I call it the "Forest Mims Oscillator" cuz in one of his radio shack circuit books was where I
    first remember seeing it as a teenager. Variants with an inductor in Q2 collector are often used in those cheap solar garden lights.

    <https://en.wikipedia.org/wiki/Forrest_Mims#/media/File:Forrest_Mims_hand_drawn_circuit_1983.jpg>

    It can be a pain to get to oscillate in LTSpice but works pretty good IRL.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to bitrex on Fri May 24 14:02:23 2024
    On 5/24/2024 2:00 PM, bitrex wrote:

    Yes, it is mysterious. Set both drain resistors to 3.3K and zoom way
    up on the two source voltages for the first 20 seconds.

    LT Spice may have some hidden asymmetry. It has to do math
    sequentially, maybe.

    In real life, parts will be plenty asymmetric. Especially jfets.


    There are  bunch of variants of this circuit, I call it the "Forest Mims Oscillator" cuz in one of his radio shack circuit books was where I
    first remember seeing it as a teenager.

    I'm pretty sure he didn't invent it though and that I've seen it in
    books from the 60s also, it was probably invented about 5 minutes after
    the PNP.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to bitrex on Fri May 24 14:41:02 2024
    "bitrex" <user@example.net> wrote in message news:6650d62f$0$2363134$882e4bbb@reader.netnews.com...
    On 5/24/2024 2:00 PM, bitrex wrote:

    Yes, it is mysterious. Set both drain resistors to 3.3K and zoom way
    up on the two source voltages for the first 20 seconds.

    LT Spice may have some hidden asymmetry. It has to do math
    sequentially, maybe.

    In real life, parts will be plenty asymmetric. Especially jfets.


    There are bunch of variants of this circuit, I call it the "Forest Mims
    Oscillator" cuz in one of his radio shack circuit books was where I first
    remember seeing it as a teenager.

    I'm pretty sure he didn't invent it though and that I've seen it in books from the 60s also, it was probably invented about 5 minutes after the PNP.

    Rufus P Turner's FET circuits is probably where I got the doing it with FETs idea from.
    It's on page 50 and easy to find a pdf.
    It also says the RC circuit should matched to within 1% but not sure why.

    I've not previously seen it with source resistors.
    The idea of not connecting the sources to ground came about because I didn't want the LED drive to affect the RC circuit.
    So in my teens I just connected the source directly to the transistor base
    with no other component and put the LED current limiting in the collector circuit.



    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to jeroen@nospam.please on Fri May 24 11:46:04 2024
    On Fri, 24 May 2024 20:33:55 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of the >>>>> view that to make an LED flash you would need something to decide when it >>>>> should be on or off. So that would be some kind of software or digital >>>>> system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor in the >> hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it could >> start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into operation >> after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 is >> 3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition.
    The right one will start all by itself.

    Jeroen Belleman

    Instead of nailing the top end of the gate resistors to V+, one can
    connect each to its own drain. That makes the fets go linear if they
    are not oscillating.

    Your right circuit sort of does that.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Edward Rawde on Fri May 24 20:33:55 2024
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of the >>>> view that to make an LED flash you would need something to decide when it >>>> should be on or off. So that would be some kind of software or digital >>>> system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart capacitor.
    So I had a complicated circuit with two more diodes and a transistor in the hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it could start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into operation after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 is 3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition.
    The right one will start all by itself.

    Jeroen Belleman

    =========================================
    Version 4
    SHEET 1 1192 680
    WIRE -80 -96 -272 -96
    WIRE 96 -96 -80 -96
    WIRE 240 -96 96 -96
    WIRE 416 -96 240 -96
    WIRE 864 -96 416 -96
    WIRE 1088 -96 864 -96
    WIRE -80 -64 -80 -96
    WIRE 96 -64 96 -96
    WIRE 240 -64 240 -96
    WIRE 416 -64 416 -96
    WIRE 864 -64 864 -96
    WIRE 1088 -64 1088 -96
    WIRE -272 32 -272 -96
    WIRE 96 48 96 16
    WIRE 112 48 96 48
    WIRE 128 48 112 48
    WIRE 240 48 240 16
    WIRE 240 48 192 48
    WIRE 768 64 704 64
    WIRE 864 64 864 16
    WIRE 864 64 848 64
    WIRE 704 112 704 64
    WIRE 944 112 704 112
    WIRE 1040 112 1008 112
    WIRE 1088 112 1088 16
    WIRE 1088 112 1040 112
    WIRE -80 128 -80 16
    WIRE 128 128 -80 128
    WIRE 384 128 192 128
    WIRE 416 128 416 16
    WIRE 416 128 384 128
    WIRE 96 160 96 48
    WIRE 416 160 416 128
    WIRE 864 160 864 64
    WIRE 992 160 864 160
    WIRE 864 176 864 160
    WIRE 1088 176 1088 112
    WIRE -80 240 -80 128
    WIRE -32 240 -80 240
    WIRE 0 240 -32 240
    WIRE 48 240 0 240
    WIRE 240 240 240 48
    WIRE 320 240 240 240
    WIRE 368 240 320 240
    WIRE 704 256 704 112
    WIRE 752 256 704 256
    WIRE 816 256 752 256
    WIRE 992 256 992 160
    WIRE 1040 256 992 256
    WIRE -272 288 -272 112
    WIRE 96 288 96 256
    WIRE 416 288 416 256
    WIRE 864 320 864 272
    WIRE 1088 320 1088 272
    WIRE 0 336 0 304
    WIRE 0 336 -272 336
    WIRE 320 336 320 304
    WIRE 320 336 0 336
    WIRE -272 352 -272 336
    WIRE -272 448 -272 432
    FLAG 96 288 0
    FLAG -272 288 0
    FLAG 416 288 0
    FLAG -32 240 G1
    FLAG 320 240 G2
    FLAG 112 48 D1
    FLAG 384 128 D2
    FLAG -272 448 0
    FLAG 1088 320 0
    FLAG 864 320 0
    FLAG 1040 112 D4
    FLAG 752 256 G3
    SYMBOL nmos 48 160 R0
    SYMATTR InstName M1
    SYMATTR Value 2N7002
    SYMBOL res 80 -80 R0
    SYMATTR InstName R1
    SYMATTR Value 1k
    SYMBOL res -96 -80 R0
    SYMATTR InstName R2
    SYMATTR Value 100k
    SYMBOL voltage -272 16 R0
    SYMATTR InstName V1
    SYMATTR Value 10
    SYMBOL nmos 368 160 R0
    SYMATTR InstName M2
    SYMATTR Value 2N7002
    SYMBOL res 400 -80 R0
    SYMATTR InstName R3
    SYMATTR Value 1k
    SYMBOL res 224 -80 R0
    SYMATTR InstName R4
    SYMATTR Value 100k
    SYMBOL cap 192 112 R90
    WINDOW 0 0 32 VBottom 2
    WINDOW 3 32 32 VTop 2
    SYMATTR InstName C1
    SYMATTR Value 100n
    SYMBOL cap 192 32 R90
    WINDOW 0 0 32 VBottom 2
    WINDOW 3 32 32 VTop 2
    SYMATTR InstName C2
    SYMATTR Value 100n
    SYMBOL voltage -272 336 R0
    SYMATTR InstName V2
    SYMATTR Value 3
    SYMBOL diode 304 240 R0
    WINDOW 0 -33 66 Left 2
    SYMATTR InstName D2
    SYMBOL diode -16 240 R0
    WINDOW 0 -40 61 Left 2
    SYMATTR InstName D3
    SYMBOL nmos 1040 176 R0
    SYMATTR InstName M3
    SYMATTR Value 2N7002
    SYMBOL nmos 816 176 R0
    SYMATTR InstName M4
    SYMATTR Value 2N7002
    SYMBOL res 1072 -80 R0
    SYMATTR InstName R5
    SYMATTR Value 1k
    SYMBOL res 848 -80 R0
    SYMATTR InstName R6
    SYMATTR Value 1k
    SYMBOL res 864 80 M270
    WINDOW 0 32 56 VTop 2
    WINDOW 3 0 56 VBottom 2
    SYMATTR InstName R7
    SYMATTR Value 100k
    SYMBOL cap 1008 96 R90
    WINDOW 0 0 32 VBottom 2
    WINDOW 3 32 32 VTop 2
    SYMATTR InstName C3
    SYMATTR Value 33n
    TEXT 88 376 Left 2 !.ic v(G1)=0
    TEXT 48 -136 Left 2 !.tran 100m

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to Jeroen Belleman on Fri May 24 14:50:19 2024
    "Jeroen Belleman" <jeroen@nospam.please> wrote in message news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of >>>>> the
    view that to make an LED flash you would need something to decide when >>>>> it
    should be on or off. So that would be some kind of software or digital >>>>> system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor in
    the
    hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it
    could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into
    operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2
    is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition.
    The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily get in the 70s. And also through hole components I can easily build a real circuit with.





    ...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to invalid@invalid.invalid on Fri May 24 13:13:23 2024
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message >news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote: >>>>
    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of >>>>>> the
    view that to make an LED flash you would need something to decide when >>>>>> it
    should be on or off. So that would be some kind of software or digital >>>>>> system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor in
    the
    hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it
    could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into
    operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2
    is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition.
    The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily get in >the 70s. And also through hole components I can easily build a real circuit >with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to john larkin on Fri May 24 16:22:23 2024
    "john larkin" <jl@650pot.com> wrote in message news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message >>news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote: >>>>>
    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be >>>>>>> of
    the
    view that to make an LED flash you would need something to decide >>>>>>> when
    it
    should be on or off. So that would be some kind of software or
    digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that
    state.

    Even when they have a hang state, luck usually kicks them off into
    oscillation. Your source resistors and asymmetric drain resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart >>>> capacitor.
    So I had a complicated circuit with two more diodes and a transistor in >>>> the
    hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it
    could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into
    operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 >>>> is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition.
    The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily get >>in
    the 70s. And also through hole components I can easily build a real
    circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with.


    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to invalid@invalid.invalid on Fri May 24 13:56:49 2024
    On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message >news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message >>>news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote: >>>>>>
    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be >>>>>>>> of
    the
    view that to make an LED flash you would need something to decide >>>>>>>> when
    it
    should be on or off. So that would be some kind of software or >>>>>>>> digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both transistors >>>>>> saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that >>>>>> state.

    Even when they have a hang state, luck usually kicks them off into >>>>>> oscillation. Your source resistors and asymmetric drain resistors >>>>>> help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart >>>>> capacitor.
    So I had a complicated circuit with two more diodes and a transistor in >>>>> the
    hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it >>>>> could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into
    operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 >>>>> is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition.
    The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily get >>>in
    the 70s. And also through hole components I can easily build a real >>>circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with.



    Use a round-end carbide dental burr. They are cheap on ebay.

    It's cool, kind of an art form. Takes some practice.

    I have a few square feet of gold-plated copperclad FR4, which is even
    nicer. Regular copperclad looks grungy after a few months.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to john larkin on Fri May 24 22:07:01 2024
    john larkin <jl@650pot.com> wrote:
    On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message
    news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message
    news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote: >>>>>>>
    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be >>>>>>>>> of
    the
    view that to make an LED flash you would need something to decide >>>>>>>>> when
    it
    should be on or off. So that would be some kind of software or >>>>>>>>> digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both transistors >>>>>>> saturated. I wonder if he jfet circuit can hang too, with Idss
    grounding both drains and not enough gain to oscillate out of that >>>>>>> state.

    Even when they have a hang state, luck usually kicks them off into >>>>>>> oscillation. Your source resistors and asymmetric drain resistors >>>>>>> help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a kickstart >>>>>> capacitor.
    So I had a complicated circuit with two more diodes and a transistor in >>>>>> the
    hope that I could detect the hang state and force it off balance.
    I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it >>>>>> could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>>>>> operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 >>>>>> is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition.
    The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily get >>>> in
    the 70s. And also through hole components I can easily build a real
    circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with.



    Use a round-end carbide dental burr. They are cheap on ebay.

    It's cool, kind of an art form. Takes some practice.

    I have a few square feet of gold-plated copperclad FR4, which is even
    nicer. Regular copperclad looks grungy after a few months.



    I’m not nearly as posh as you are, so for my purposes a spritz of Krylon clear acrylic on a clean board is a ticket.

    You can solder right through it, and it keeps the copper looking nice for a long time.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to Phil Hobbs on Fri May 24 18:20:58 2024
    "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message news:v2r325$2h00c$1@dont-email.me...
    john larkin <jl@650pot.com> wrote:
    On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message
    news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message
    news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> >>>>>>>> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to >>>>>>>>>> be
    of
    the
    view that to make an LED flash you would need something to decide >>>>>>>>>> when
    it
    should be on or off. So that would be some kind of software or >>>>>>>>>> digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both transistors >>>>>>>> saturated. I wonder if he jfet circuit can hang too, with Idss >>>>>>>> grounding both drains and not enough gain to oscillate out of that >>>>>>>> state.

    Even when they have a hang state, luck usually kicks them off into >>>>>>>> oscillation. Your source resistors and asymmetric drain resistors >>>>>>>> help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a
    kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor >>>>>>> in
    the
    hope that I could detect the hang state and force it off balance. >>>>>>> I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it >>>>>>> could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>>>>>> operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when >>>>>>> R2
    is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours,
    with a hangup state. I start it by specifying an initial condition. >>>>>> The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily >>>>> get
    in
    the 70s. And also through hole components I can easily build a real
    circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with.



    Use a round-end carbide dental burr. They are cheap on ebay.

    It's cool, kind of an art form. Takes some practice.

    I have a few square feet of gold-plated copperclad FR4, which is even
    nicer. Regular copperclad looks grungy after a few months.



    I'm not nearly as posh as you are

    Not sure why that made me laugh.

    , so for my purposes a spritz of Krylon
    clear acrylic on a clean board is a ticket.

    You can solder right through it, and it keeps the copper looking nice for
    a
    long time.

    I seem to remember, a long long time ago using copper clad board, some clear sticky tape and a very sharp knife.
    Followed by Ferric Chloride.
    An etch resist pen could also be used if the tape removal didn't go exactly
    as planned.

    But yes it's true that after removing the etch resist you might want
    something to keep the copper looking nice and shiny.


    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC
    /
    Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to Phil Hobbs on Fri May 24 19:06:50 2024
    "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message news:v2r4od$2h9gp$1@dont-email.me...
    Edward Rawde <invalid@invalid.invalid> wrote:
    "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
    news:v2r325$2h00c$1@dont-email.me...
    john larkin <jl@650pot.com> wrote:
    On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message
    news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message
    news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> >>>>>>>>>> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to >>>>>>>>>>>> be
    of
    the
    view that to make an LED flash you would need something to >>>>>>>>>>>> decide
    when
    it
    should be on or off. So that would be some kind of software or >>>>>>>>>>>> digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both
    transistors
    saturated. I wonder if he jfet circuit can hang too, with Idss >>>>>>>>>> grounding both drains and not enough gain to oscillate out of >>>>>>>>>> that
    state.

    Even when they have a hang state, luck usually kicks them off >>>>>>>>>> into
    oscillation. Your source resistors and asymmetric drain
    resistors
    help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a >>>>>>>>> kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a
    transistor
    in
    the
    hope that I could detect the hang state and force it off balance. >>>>>>>>> I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how >>>>>>>>> it
    could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>>>>>>>> operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing >>>>>>>>> when
    R2
    is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours, >>>>>>>> with a hangup state. I start it by specifying an initial condition. >>>>>>>> The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could
    easily
    get
    in
    the 70s. And also through hole components I can easily build a real >>>>>>> circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with. >>>>>>


    Use a round-end carbide dental burr. They are cheap on ebay.

    It's cool, kind of an art form. Takes some practice.

    I have a few square feet of gold-plated copperclad FR4, which is even
    nicer. Regular copperclad looks grungy after a few months.



    I'm not nearly as posh as you are

    Not sure why that made me laugh.

    , so for my purposes a spritz of Krylon
    clear acrylic on a clean board is a ticket.

    You can solder right through it, and it keeps the copper looking nice
    for
    a
    long time.

    I seem to remember, a long long time ago using copper clad board, some
    clear
    sticky tape and a very sharp knife.
    Followed by Ferric Chloride.
    An etch resist pen could also be used if the tape removal didn't go
    exactly
    as planned.

    But yes it's true that after removing the etch resist you might want
    something to keep the copper looking nice and shiny.


    Oh, I haven't etched a PCB in forty-odd years. This is strictly dead-bug stuff.

    47 years ago in my case when I made an external keyboard because the one supplied by Sinclair was useless.
    https://en.wikipedia.org/wiki/MK14


    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC
    /
    Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Edward Rawde on Fri May 24 22:35:57 2024
    Edward Rawde <invalid@invalid.invalid> wrote:
    "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message news:v2r325$2h00c$1@dont-email.me...
    john larkin <jl@650pot.com> wrote:
    On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message
    news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message
    news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> >>>>>>>>> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to >>>>>>>>>>> be
    of
    the
    view that to make an LED flash you would need something to decide >>>>>>>>>>> when
    it
    should be on or off. So that would be some kind of software or >>>>>>>>>>> digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both transistors >>>>>>>>> saturated. I wonder if he jfet circuit can hang too, with Idss >>>>>>>>> grounding both drains and not enough gain to oscillate out of that >>>>>>>>> state.

    Even when they have a hang state, luck usually kicks them off into >>>>>>>>> oscillation. Your source resistors and asymmetric drain resistors >>>>>>>>> help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a
    kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor >>>>>>>> in
    the
    hope that I could detect the hang state and force it off balance. >>>>>>>> I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it >>>>>>>> could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>>>>>>> operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when >>>>>>>> R2
    is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours, >>>>>>> with a hangup state. I start it by specifying an initial condition. >>>>>>> The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily >>>>>> get
    in
    the 70s. And also through hole components I can easily build a real >>>>>> circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with. >>>>>


    Use a round-end carbide dental burr. They are cheap on ebay.

    It's cool, kind of an art form. Takes some practice.

    I have a few square feet of gold-plated copperclad FR4, which is even
    nicer. Regular copperclad looks grungy after a few months.



    I'm not nearly as posh as you are

    Not sure why that made me laugh.

    , so for my purposes a spritz of Krylon
    clear acrylic on a clean board is a ticket.

    You can solder right through it, and it keeps the copper looking nice for
    a
    long time.

    I seem to remember, a long long time ago using copper clad board, some clear sticky tape and a very sharp knife.
    Followed by Ferric Chloride.
    An etch resist pen could also be used if the tape removal didn't go exactly as planned.

    But yes it's true that after removing the etch resist you might want something to keep the copper looking nice and shiny.


    Oh, I haven’t etched a PCB in forty-odd years. This is strictly dead-bug stuff.

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Fri May 24 16:59:58 2024
    On Fri, 24 May 2024 22:35:57 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Edward Rawde <invalid@invalid.invalid> wrote:
    "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
    news:v2r325$2h00c$1@dont-email.me...
    john larkin <jl@650pot.com> wrote:
    On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message
    news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message
    news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> >>>>>>>>>> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to >>>>>>>>>>>> be
    of
    the
    view that to make an LED flash you would need something to decide >>>>>>>>>>>> when
    it
    should be on or off. So that would be some kind of software or >>>>>>>>>>>> digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both transistors >>>>>>>>>> saturated. I wonder if he jfet circuit can hang too, with Idss >>>>>>>>>> grounding both drains and not enough gain to oscillate out of that >>>>>>>>>> state.

    Even when they have a hang state, luck usually kicks them off into >>>>>>>>>> oscillation. Your source resistors and asymmetric drain resistors >>>>>>>>>> help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up.


    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a >>>>>>>>> kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor >>>>>>>>> in
    the
    hope that I could detect the hang state and force it off balance. >>>>>>>>> I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it >>>>>>>>> could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k.

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>>>>>>>> operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when >>>>>>>>> R2
    is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours, >>>>>>>> with a hangup state. I start it by specifying an initial condition. >>>>>>>> The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily >>>>>>> get
    in
    the 70s. And also through hole components I can easily build a real >>>>>>> circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with. >>>>>>


    Use a round-end carbide dental burr. They are cheap on ebay.

    It's cool, kind of an art form. Takes some practice.

    I have a few square feet of gold-plated copperclad FR4, which is even
    nicer. Regular copperclad looks grungy after a few months.



    I'm not nearly as posh as you are

    Not sure why that made me laugh.

    , so for my purposes a spritz of Krylon
    clear acrylic on a clean board is a ticket.

    You can solder right through it, and it keeps the copper looking nice for >>> a
    long time.

    I seem to remember, a long long time ago using copper clad board, some clear >> sticky tape and a very sharp knife.
    Followed by Ferric Chloride.
    An etch resist pen could also be used if the tape removal didn't go exactly >> as planned.

    But yes it's true that after removing the etch resist you might want
    something to keep the copper looking nice and shiny.

    Soft Scrub. It's basically an optical polish.



    Oh, I haven’t etched a PCB in forty-odd years. This is strictly dead-bug >stuff.


    Insect cruelty. Plus you have to count their tiny feets backwards.



    Cheers

    Phil Hobbs

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to john larkin on Sat May 25 00:45:31 2024
    john larkin <jl@650pot.com> wrote:
    On Fri, 24 May 2024 22:35:57 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Edward Rawde <invalid@invalid.invalid> wrote:
    "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
    news:v2r325$2h00c$1@dont-email.me...
    john larkin <jl@650pot.com> wrote:
    On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message
    news:uts15jlh0oo1hin58uu4a574kg5q3j9q5b@4ax.com...
    On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Jeroen Belleman" <jeroen@nospam.please> wrote in message
    news:v2qmeq$2eknc$1@dont-email.me...
    On 5/24/24 17:59, Edward Rawde wrote:
    "john larkin" <jl@650pot.com> wrote in message
    news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> >>>>>>>>>>> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to >>>>>>>>>>>>> be
    of
    the
    view that to make an LED flash you would need something to decide >>>>>>>>>>>>> when
    it
    should be on or off. So that would be some kind of software or >>>>>>>>>>>>> digital
    system.
    ...


    The classic NPN astable circuit can hang up, with both transistors >>>>>>>>>>> saturated. I wonder if he jfet circuit can hang too, with Idss >>>>>>>>>>> grounding both drains and not enough gain to oscillate out of that >>>>>>>>>>> state.

    Even when they have a hang state, luck usually kicks them off into >>>>>>>>>>> oscillation. Your source resistors and asymmetric drain resistors >>>>>>>>>>> help it start up. Try making both drain resistors 3.3K.

    If you make the source resistors lower, it will hang up. >>>>>>>>>>>

    Yes I noticed both points when I was designing it.
    I wanted to have it start up by itself, preferably without a >>>>>>>>>> kickstart
    capacitor.
    So I had a complicated circuit with two more diodes and a transistor >>>>>>>>>> in
    the
    hope that I could detect the hang state and force it off balance. >>>>>>>>>> I couldn't get that to work
    Then I accidentally made R2 3,3k and R6 3.3k and I didn't see how it >>>>>>>>>> could
    start so quickly with no other help.
    Eventually I noticed 3,3k which maybe LTSpice takes as 3k. >>>>>>>>>>
    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>>>>>>>>> operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when >>>>>>>>>> R2
    is
    3.3k?

    Below are a pair of astable circuits. The left one is like yours, >>>>>>>>> with a hangup state. I start it by specifying an initial condition. >>>>>>>>> The right one will start all by itself.


    Thanks for that. I guess I'm biased towards components I could easily >>>>>>>> get
    in
    the 70s. And also through hole components I can easily build a real >>>>>>>> circuit
    with.



    I like to use surface-mount parts on a Dremeled PCB.

    https://www.dropbox.com/s/7bihbjbaojvta0z/Z382_1.JPG?raw=1

    https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

    You can do fast, 50-ohm picosecond stuff this way too.


    Thanks I probably do have some copper clad board I could do that with. >>>>>>>


    Use a round-end carbide dental burr. They are cheap on ebay.

    It's cool, kind of an art form. Takes some practice.

    I have a few square feet of gold-plated copperclad FR4, which is even >>>>> nicer. Regular copperclad looks grungy after a few months.



    I'm not nearly as posh as you are

    Not sure why that made me laugh.

    , so for my purposes a spritz of Krylon
    clear acrylic on a clean board is a ticket.

    You can solder right through it, and it keeps the copper looking nice for >>>> a
    long time.

    I seem to remember, a long long time ago using copper clad board, some clear
    sticky tape and a very sharp knife.
    Followed by Ferric Chloride.
    An etch resist pen could also be used if the tape removal didn't go exactly >>> as planned.

    But yes it's true that after removing the etch resist you might want
    something to keep the copper looking nice and shiny.

    Soft Scrub. It's basically an optical polish.

    I generally use Barkeeper’s Friend on a damp paper towel. (That’s what’s under the bathroom sink at the lab. )

    Oh, I havenÂ’t etched a PCB in forty-odd years. This is strictly dead-bug
    stuff.


    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Mike Monett VE3BTI@21:1/5 to Phil Hobbs on Sat May 25 01:59:38 2024
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the important signals are, or how the circuit works.

    Many high frequency ic's have a ground tab that must be connected to
    ground. This is not possible with dead bugs.

    Often not all of a prototype must be on a copperclad ground plane.
    Perpheral supporting circuits can be placed on a prototype board, with a section of ground plane mounted on the proto board as needed. This makes mounting test points and input and output signals much easier.

    Amazon has a large selection of suitable proto boards:

    https://www.amazon.ca/s?k=prototype+pcb+board


    --
    MRM

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to spamme@not.com on Fri May 24 22:56:02 2024
    "Mike Monett VE3BTI" <spamme@not.com> wrote in message news:XnsB17CDFBC01F77idtokenpost@135.181.20.170...
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the important signals are, or how the circuit works.

    Many high frequency ic's have a ground tab that must be connected to
    ground. This is not possible with dead bugs.

    Often not all of a prototype must be on a copperclad ground plane.
    Perpheral supporting circuits can be placed on a prototype board, with a section of ground plane mounted on the proto board as needed. This makes mounting test points and input and output signals much easier.

    Amazon has a large selection of suitable proto boards:

    https://www.amazon.ca/s?k=prototype+pcb+board


    I used to like Speedwire, particularly if I wanted and 8-bit CPU and a bunch
    of 22V10s.
    But it's no surprise I can barely find any reference to it now.

    https://www.google.com/search?&q=speedwire+bicc-vero&tbm=isch

    https://www.edn.com/wp-content/uploads/contenteetimes-images-01mdunn-benchtalk-proto4.jpg


    --
    MRM

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to john larkin on Fri May 24 23:19:03 2024
    "john larkin" <jl@650pot.com> wrote in message news:phk15jlc055d4p4b1qlicodl16v85u00d9@4ax.com...
    On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message >>news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote:

    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde" >>>><invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of >>>>>the
    view that to make an LED flash you would need something to decide when >>>>>it
    should be on or off. So that would be some kind of software or digital >>>>>system.
    ...

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 is >>3.3k?


    Yes, it is mysterious. Set both drain resistors to 3.3K and zoom way
    up on the two source voltages for the first 20 seconds.

    Why the crossover at 15 seconds?
    I think reliable startup of the simulated symmetrical version has to be a simulation artefact.

    Now I'm curious what the real circuit would do.
    I may have suitable parts.


    LT Spice may have some hidden asymmetry. It has to do math
    sequentially, maybe.

    In real life, parts will be plenty asymmetric. Especially jfets.


    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to spamme@not.com on Fri May 24 20:22:13 2024
    On Sat, 25 May 2024 01:59:38 -0000 (UTC), Mike Monett VE3BTI
    <spamme@not.com> wrote:

    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the >important signals are, or how the circuit works.

    Many high frequency ic's have a ground tab that must be connected to
    ground. This is not possible with dead bugs.

    Often not all of a prototype must be on a copperclad ground plane.
    Perpheral supporting circuits can be placed on a prototype board, with a >section of ground plane mounted on the proto board as needed. This makes >mounting test points and input and output signals much easier.

    Amazon has a large selection of suitable proto boards:

    https://www.amazon.ca/s?k=prototype+pcb+board

    We have a folder on a company shared drive called J:\Protos. Every
    project gets a sub-folder, like Z356 for example. The folder are
    logged in Protos.txt. There's another file that explains the rules.

    A folder archives everything about a prototype. Schematic, data
    sheets, pictures of the built thing, test notes, scope pics, anything
    worth remembering. The proto board itself would be labeled Z356.

    https://www.dropbox.com/s/48c8qh80yhbehj6/Z356_Top.JPG?raw=1

    I like to use little surface-mount IC adapters, held down with
    double-stick foam stuff.

    Some of the Z's are just parts tests or anything else worth
    documenting. Some are real multilayer PCBs.

    This one is world-famous. It's in AoE3.

    https://www.dropbox.com/scl/fi/ky6ppt92q7jd6envvuje4/Z420_C1.JPG?rlkey=iqey9s6suqb9n62bedu70rxkf&raw=1

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  • From john larkin@21:1/5 to invalid@invalid.invalid on Fri May 24 20:24:39 2024
    On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Mike Monett VE3BTI" <spamme@not.com> wrote in message >news:XnsB17CDFBC01F77idtokenpost@135.181.20.170...
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the
    important signals are, or how the circuit works.

    Many high frequency ic's have a ground tab that must be connected to
    ground. This is not possible with dead bugs.

    Often not all of a prototype must be on a copperclad ground plane.
    Perpheral supporting circuits can be placed on a prototype board, with a
    section of ground plane mounted on the proto board as needed. This makes
    mounting test points and input and output signals much easier.

    Amazon has a large selection of suitable proto boards:

    https://www.amazon.ca/s?k=prototype+pcb+board


    I used to like Speedwire, particularly if I wanted and 8-bit CPU and a bunch >of 22V10s.
    But it's no surprise I can barely find any reference to it now.

    https://www.google.com/search?&q=speedwire+bicc-vero&tbm=isch

    https://www.edn.com/wp-content/uploads/contenteetimes-images-01mdunn-benchtalk-proto4.jpg


    --
    MRM


    It's cheap and easy now to make a few double-side or multilayer PCBs
    for anything complex.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to spamme@not.com on Sat May 25 03:36:06 2024
    Mike Monett VE3BTI <spamme@not.com> wrote:
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the
    important signals are, or how the circuit works.

    Nah. I build them inside the lid of a cast aluminum stomp box, and put a
    paper schematic inside. No worries.



    Many high frequency ic's have a ground tab that must be connected to
    ground. This is not possible with dead bugs.

    Often not all of a prototype must be on a copperclad ground plane.
    Perpheral supporting circuits can be placed on a prototype board, with a section of ground plane mounted on the proto board as needed. This makes mounting test points and input and output signals much easier.

    Amazon has a large selection of suitable proto boards:

    https://www.amazon.ca/s?k=prototype+pcb+board



    More trouble than it’s worth IME.

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to john larkin on Fri May 24 23:39:02 2024
    "john larkin" <jl@650pot.com> wrote in message news:obm25jtajqj96tjutjmo4vhlvglje74444@4ax.com...
    On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Mike Monett VE3BTI" <spamme@not.com> wrote in message >>news:XnsB17CDFBC01F77idtokenpost@135.181.20.170...
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the
    important signals are, or how the circuit works.

    Many high frequency ic's have a ground tab that must be connected to
    ground. This is not possible with dead bugs.

    Often not all of a prototype must be on a copperclad ground plane.
    Perpheral supporting circuits can be placed on a prototype board, with a >>> section of ground plane mounted on the proto board as needed. This makes >>> mounting test points and input and output signals much easier.

    Amazon has a large selection of suitable proto boards:

    https://www.amazon.ca/s?k=prototype+pcb+board


    I used to like Speedwire, particularly if I wanted and 8-bit CPU and a >>bunch
    of 22V10s.
    But it's no surprise I can barely find any reference to it now.

    https://www.google.com/search?&q=speedwire+bicc-vero&tbm=isch
    https://www.edn.com/wp-content/uploads/contenteetimes-images-01mdunn-benchtalk-proto4.jpg


    --
    MRM


    It's cheap and easy now to make a few double-side or multilayer PCBs
    for anything complex.

    True but you can reuse a speedwire board :)

    What PCB design system/software do you use?



    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to invalid@invalid.invalid on Sat May 25 08:23:24 2024
    On Fri, 24 May 2024 23:19:03 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message >news:phk15jlc055d4p4b1qlicodl16v85u00d9@4ax.com...
    On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message >>>news:bk815jh3skuecf1tap8o41rpgdh5kkq8o5@4ax.com...
    On Thu, 23 May 2024 13:06:46 -0700, john larkin <jl@650pot.com> wrote: >>>>
    On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde" >>>>><invalid@invalid.invalid> wrote:

    I was having a conversation with a younger person who seemed to be of >>>>>>the
    view that to make an LED flash you would need something to decide when >>>>>>it
    should be on or off. So that would be some kind of software or digital >>>>>>system.
    ...

    If R2 and R6 are both 3.3k then LTSpice says it slowly drifts into >>>operation
    after 40 seconds.
    But why does it go one way and not the other?
    Is that an artefact of asymmetry in the simulation?
    Or is there some hidden asymmetry in the circuit I'm not seeing when R2 is >>>3.3k?


    Yes, it is mysterious. Set both drain resistors to 3.3K and zoom way
    up on the two source voltages for the first 20 seconds.

    Why the crossover at 15 seconds?

    Mystrerious!

    Maybe some math/Spice guru can suggest why.


    I think reliable startup of the simulated symmetrical version has to be a >simulation artefact.

    I have seen oscillators that never started in Spice, absent being
    goosed somehow.

    My LC Colpitts oscillators generally don't start on their own. In real
    life, I force them to start instantly.


    Now I'm curious what the real circuit would do.
    I may have suitable parts.

    It will no doubt start, from noise, part asymmetey, and the powerup
    transient.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to invalid@invalid.invalid on Sat May 25 08:42:18 2024
    On Fri, 24 May 2024 23:39:02 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message >news:obm25jtajqj96tjutjmo4vhlvglje74444@4ax.com...
    On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Mike Monett VE3BTI" <spamme@not.com> wrote in message >>>news:XnsB17CDFBC01F77idtokenpost@135.181.20.170...
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic. >>>>
    Six months later, you will have no idea what the circuit is, where the >>>> important signals are, or how the circuit works.

    Many high frequency ic's have a ground tab that must be connected to
    ground. This is not possible with dead bugs.

    Often not all of a prototype must be on a copperclad ground plane.
    Perpheral supporting circuits can be placed on a prototype board, with a >>>> section of ground plane mounted on the proto board as needed. This makes >>>> mounting test points and input and output signals much easier.

    Amazon has a large selection of suitable proto boards:

    https://www.amazon.ca/s?k=prototype+pcb+board


    I used to like Speedwire, particularly if I wanted and 8-bit CPU and a >>>bunch
    of 22V10s.
    But it's no surprise I can barely find any reference to it now.

    https://www.google.com/search?&q=speedwire+bicc-vero&tbm=isch
    https://www.edn.com/wp-content/uploads/contenteetimes-images-01mdunn-benchtalk-proto4.jpg


    --
    MRM


    It's cheap and easy now to make a few double-side or multilayer PCBs
    for anything complex.

    True but you can reuse a speedwire board :)

    Yuk! I remember how awful WireWrap protos were. I wrote a PDP-11
    program to optimize wrapping, the traveling-salesman problem.

    One nice thing about PCB protos is that you can keep them around
    forever, for future reference. Vias and ground planes and 50-ohm
    traces and edge-launch SMA connectors are all good. A spare unstuffed
    board or two is nice to have around too.

    I often put several different circuits on one board, and shear them
    apart.

    https://www.dropbox.com/s/lo1a43wi9ta7qry/Z-boards.jpg?raw=1


    What PCB design system/software do you use?

    PADS. We've been using PADS since the DOS/floppy disk days. It works
    well enough. We use the same ever-growing parts library and can open decades-old projects.

    What's weird is that Digikey has cheap proto "redboards" now but claim
    that they won't work from PADS files. Gerbers is Gerbers, I'd think.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Sat May 25 08:47:09 2024
    On Sat, 25 May 2024 03:36:06 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Mike Monett VE3BTI <spamme@not.com> wrote:
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the
    important signals are, or how the circuit works.

    Nah. I build them inside the lid of a cast aluminum stomp box, and put a >paper schematic inside. No worries.

    Where do you document the results?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to john larkin on Sat May 25 17:21:08 2024
    john larkin <jl@650pot.com> wrote:
    On Sat, 25 May 2024 03:36:06 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Mike Monett VE3BTI <spamme@not.com> wrote:
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic.

    Six months later, you will have no idea what the circuit is, where the
    important signals are, or how the circuit works.

    Nah. I build them inside the lid of a cast aluminum stomp box, and put a
    paper schematic inside. No worries.

    Where do you document the results?



    Depends. If it’s a small test instrument, usually in my lab book. If it’s for a product or an experiment, I mostly use Markdown files in the corresponding git repository.

    We keep private repos on github and gitlab, as well as bare repos on
    various computers and NAS boxes in different locations.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Sat May 25 10:54:00 2024
    On Sat, 25 May 2024 17:21:08 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    john larkin <jl@650pot.com> wrote:
    On Sat, 25 May 2024 03:36:06 -0000 (UTC), Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Mike Monett VE3BTI <spamme@not.com> wrote:
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards.

    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic. >>>
    Six months later, you will have no idea what the circuit is, where the >>>> important signals are, or how the circuit works.

    Nah. I build them inside the lid of a cast aluminum stomp box, and put a >>> paper schematic inside. No worries.

    Where do you document the results?



    Depends. If it’s a small test instrument, usually in my lab book. If it’s >for a product or an experiment, I mostly use Markdown files in the >corresponding git repository.

    We keep private repos on github and gitlab, as well as bare repos on
    various computers and NAS boxes in different locations.

    Cheers

    Phil Hobbs

    I have 7 engineers now, and we've structured the prototyping and
    subsequent learning to encourage knowledge and experience sharing.

    Our material control system tries to do that too. Every part in stock
    has an optional PDATA folder with data sheets, test data, notes,
    warnings.


    Search results <opamp++buggy> 05-25-2024
    10:52:27

    PART CLASS SUBCLASS DESCRIPTION MFR1
    MPN1 PRICE STOCK OLD PART
    ======== ============ ================ ========================
    ========== ================= ======= ====== ========
    300-7062 ICS OPAMP 30V SO8 2X THS3062 BUGGY IF TEXAS
    INST THS3062DDA 10.50 647 30362

    --- SoupGate-Win32 v1.05
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  • From Edward Rawde@21:1/5 to john larkin on Sat May 25 14:11:24 2024
    "john larkin" <jl@650pot.com> wrote in message news:8k045j52u800u8s00ebhbkk0v408jgugog@4ax.com...
    On Fri, 24 May 2024 23:39:02 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "john larkin" <jl@650pot.com> wrote in message >>news:obm25jtajqj96tjutjmo4vhlvglje74444@4ax.com...
    On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
    <invalid@invalid.invalid> wrote:

    "Mike Monett VE3BTI" <spamme@not.com> wrote in message >>>>news:XnsB17CDFBC01F77idtokenpost@135.181.20.170...
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Insect cruelty. Plus you have to count their tiny feets backwards. >>>>>>
    The only good bugs is dead bugs. ;)

    Cheers

    Phil Hobbs

    The major flaw with dead bugs is you lose the identification of the ic. >>>>>
    ...


    It's cheap and easy now to make a few double-side or multilayer PCBs
    for anything complex.

    True but you can reuse a speedwire board :)

    Yuk! I remember how awful WireWrap protos were. I wrote a PDP-11
    program to optimize wrapping, the traveling-salesman problem.

    I hated wire wrap but liked speedwire.
    If it wasn't speedwire it was a soldering iron and what we called veroboard. Non shrink-back ptfe wire was useful too.


    One nice thing about PCB protos is that you can keep them around
    forever, for future reference. Vias and ground planes and 50-ohm
    traces and edge-launch SMA connectors are all good. A spare unstuffed
    board or two is nice to have around too.

    I often put several different circuits on one board, and shear them
    apart.

    https://www.dropbox.com/s/lo1a43wi9ta7qry/Z-boards.jpg?raw=1


    What PCB design system/software do you use?

    PADS. We've been using PADS since the DOS/floppy disk days.

    Ok not one I've used.

    It works
    well enough. We use the same ever-growing parts library and can open decades-old projects.

    Yes I've had that problem. I think it was OrCAD which couldn't open older versions of its own files.


    What's weird is that Digikey has cheap proto "redboards" now but claim
    that they won't work from PADS files. Gerbers is Gerbers, I'd think.


    --- SoupGate-Win32 v1.05
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