Discussion:
An actual circuit
(too old to reply)
Edward Rawde
2024-05-23 19:35:00 UTC
Permalink
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
john larkin
2024-05-23 20:06:46 UTC
Permalink
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
Post by Edward Rawde
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
john larkin
2024-05-24 14:38:12 UTC
Permalink
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
Edward Rawde
2024-05-24 15:59:31 UTC
Permalink
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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?
john larkin
2024-05-24 17:55:26 UTC
Permalink
On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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.
bitrex
2024-05-24 18:00:06 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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.

<Loading Image...>

It can be a pain to get to oscillate in LTSpice but works pretty good IRL.
bitrex
2024-05-24 18:02:23 UTC
Permalink
Post by john larkin
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.
Edward Rawde
2024-05-24 18:41:02 UTC
Permalink
Post by john larkin
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.
Edward Rawde
2024-05-25 03:19:03 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
Post by Edward Rawde
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.
Post by john larkin
LT Spice may have some hidden asymmetry. It has to do math
sequentially, maybe.
In real life, parts will be plenty asymmetric. Especially jfets.
john larkin
2024-05-25 15:23:24 UTC
Permalink
On Fri, 24 May 2024 23:19:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 11:59:31 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
Post by Edward Rawde
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.
Post by Edward Rawde
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.
Post by Edward Rawde
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.
Jeroen Belleman
2024-05-24 18:33:55 UTC
Permalink
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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
john larkin
2024-05-24 18:46:04 UTC
Permalink
On Fri, 24 May 2024 20:33:55 +0200, Jeroen Belleman
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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.
Edward Rawde
2024-05-24 18:50:19 UTC
Permalink
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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.





...
john larkin
2024-05-24 20:13:23 UTC
Permalink
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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.

Loading Image...

Loading Image...

You can do fast, 50-ohm picosecond stuff this way too.
Edward Rawde
2024-05-24 20:22:23 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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.
john larkin
2024-05-24 20:56:49 UTC
Permalink
On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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.
Phil Hobbs
2024-05-24 22:07:01 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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
2024-05-24 22:20:58 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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
Phil Hobbs
2024-05-24 22:35:57 UTC
Permalink
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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
Edward Rawde
2024-05-24 23:06:50 UTC
Permalink
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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
john larkin
2024-05-24 23:59:58 UTC
Permalink
On Fri, 24 May 2024 22:35:57 -0000 (UTC), Phil Hobbs
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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
Phil Hobbs
2024-05-25 00:45:31 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 22:35:57 -0000 (UTC), Phil Hobbs
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 16:22:23 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 14:50:19 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Jeroen Belleman
Post by Edward Rawde
Post by john larkin
Post by john larkin
On Thu, 23 May 2024 15:35:00 -0400, "Edward Rawde"
Post by Edward Rawde
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.
...
Post by john larkin
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. )
Post by john larkin
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.
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
Mike Monett VE3BTI
2024-05-25 01:59:38 UTC
Permalink
Post by Phil Hobbs
Post by john larkin
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
Edward Rawde
2024-05-25 02:56:02 UTC
Permalink
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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.
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

Loading Image...
Post by Mike Monett VE3BTI
--
MRM
john larkin
2024-05-25 03:24:39 UTC
Permalink
On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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.
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
Post by Mike Monett VE3BTI
--
MRM
It's cheap and easy now to make a few double-side or multilayer PCBs
for anything complex.
Edward Rawde
2024-05-25 03:39:02 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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.
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
Post by Mike Monett VE3BTI
--
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?
john larkin
2024-05-25 15:42:18 UTC
Permalink
On Fri, 24 May 2024 23:39:02 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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.
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
Post by Mike Monett VE3BTI
--
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.

Loading Image...
Post by Edward Rawde
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.
Edward Rawde
2024-05-25 18:11:24 UTC
Permalink
Post by john larkin
On Fri, 24 May 2024 23:39:02 -0400, "Edward Rawde"
Post by Edward Rawde
Post by john larkin
On Fri, 24 May 2024 22:56:02 -0400, "Edward Rawde"
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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.
...
Post by john larkin
Post by Edward Rawde
Post by john larkin
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.
Post by john larkin
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
Post by Edward Rawde
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.
Post by john larkin
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.
Post by john larkin
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.
john larkin
2024-05-25 03:22:13 UTC
Permalink
On Sat, 25 May 2024 01:59:38 -0000 (UTC), Mike Monett VE3BTI
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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.
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.

Loading Image...

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.

Loading Image...
Phil Hobbs
2024-05-25 03:36:06 UTC
Permalink
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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.
Post by Mike Monett VE3BTI
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.
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
john larkin
2024-05-25 15:47:09 UTC
Permalink
On Sat, 25 May 2024 03:36:06 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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?
Phil Hobbs
2024-05-25 17:21:08 UTC
Permalink
Post by john larkin
On Sat, 25 May 2024 03:36:06 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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
john larkin
2024-05-25 17:54:00 UTC
Permalink
On Sat, 25 May 2024 17:21:08 -0000 (UTC), Phil Hobbs
Post by john larkin
On Sat, 25 May 2024 03:36:06 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by Mike Monett VE3BTI
Post by Phil Hobbs
Post by john larkin
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
Loading...