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
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.
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.
"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?
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.
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.
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.
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
"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?
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" <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.
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.
"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.
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.
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
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
"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.
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
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 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.
Insect cruelty. Plus you have to count their tiny feets backwards.
The only good bugs is dead bugs. ;)
Cheers
Phil Hobbs
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
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.
LT Spice may have some hidden asymmetry. It has to do math
sequentially, maybe.
In real life, parts will be plenty asymmetric. Especially jfets.
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
"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
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
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.
"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.
"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?
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.
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?
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
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.
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.
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