Callins capacitor?...

[server]

On Sat, 12 Dec 2020 21:19:50 +0200, Tauno Voipio
<tauno.voipio@notused.fi.invalid> wrote:

On 12.12.20 6.49, Don wrote:
The earlier Callins link was only for reference to give people an idea
of the price and physical characteristics.

My questions actually pertain to a 100 ?F 6 V Callins, which looks
identical. It\'s used in a PAIA VCO module from the 1970s. The
schematic\'s shown here:

https://crcomp.net/paia/2720-2A.png

C7 is the Callins. C6 is a plain vanilla electrolytic in a can. They
both have a value of 100 ?F.

Although the simpleminded answer goes through everyone\'s mind first, it
doesn\'t add up. Why pay more for a Callins back in the day? Why not buy
twice as many electrolytics in cans to get a better price break?
Or, if Callins was the cheap alternative back then, why pay more
for electrolytics in cans?

Perhaps the answer\'s as simple as the late John Simonton inheriting a
pile of Callins. It\'s too late to ask John, but there\'s a PAIA forum,
which may supply some answers, provided they process my registration.
For the time being, the Callins will be substituted with a new
electrolytic in a can.

Danke,


There must be some audio magic inside the Callins, but I see
it difficult to get any advantage in a power supply filter.
If you\'re not happy with a garden-variety aluminum, get a
tantalum one, and please, with a little more than 6V rating,
as the power line is nominally 6V.

Derate tants about 3:1 on a supply rail. That seems to be reliable.



--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Steve Wilson]

jlarkin@highlandsniptechnology.com wrote:

> Derate tants about 3:1 on a supply rail. That seems to be reliable.

If you have to derate, there goes the size advantage. If the tant is at the
end of a long power supply lead, there could be a spike when the power is
attached. See Williams for more info.

With the risks of tantalum, why not use poly instead?



--
The best designs occur in the theta state. - sw

 

[Cydrome Leader]

In sci.electronics.design piglet <erichpwagner@hotmail.com> wrote:

On 12/12/2020 4:49 am, Don wrote:
The earlier Callins link was only for reference to give people an idea
of the price and physical characteristics.

My questions actually pertain to a 100 ??F 6 V Callins, which looks
identical. It\'s used in a PAIA VCO module from the 1970s. The
schematic\'s shown here:

https://crcomp.net/paia/2720-2A.png

C7 is the Callins. C6 is a plain vanilla electrolytic in a can. They
both have a value of 100 ??F.

Although the simpleminded answer goes through everyone\'s mind first, it
doesn\'t add up. Why pay more for a Callins back in the day? Why not buy
twice as many electrolytics in cans to get a better price break?
Or, if Callins was the cheap alternative back then, why pay more
for electrolytics in cans?

Perhaps the answer\'s as simple as the late John Simonton inheriting a
pile of Callins. It\'s too late to ask John, but there\'s a PAIA forum,
which may supply some answers, provided they process my registration.
For the time being, the Callins will be substituted with a new
electrolytic in a can.

Danke,


I have some similar epoxy sealed aluminum electrolytics from the mid
1970s made by Roederstein (now incorporated into Vishay). At the time
they cost only a few percent more than metal can/elastomer seal
capacitors. There is absolutely nothing special about the electrical
characteristics needed of C6 and C7 in that unsavoury circuit and my
guess is that the assemblers just randomly picked that brand.

piglet

\"BULLSHIT\". phil allison told me to let you know this.

 

[Don]

In sci.electronics.design Don <g@crcomp.net> wrote:
> In sci.electronics.design legg <legg@nospam.magma.ca> wrote:

<snip>

If it was designed to use a Callins cap, then Callins
would show up on the schematic and BOM.

As it is, specifying a 6V electrolytic to filter a
6.2V reference is probably a mistake.

Excellent observation! There\'s actually a 25 V Callins on the board
itself. So, there\'s definitely a mistake on the schematic.

Whoops, it turns out the (loose) 25 V Callins belongs to another module.
Although the VCO\'s original 6 V Callins is long gone from my PCB, Inet
images show it present on other people\'s VCOs.

It also turns out there\'s a typo with D4. Its correct value is 5.6 V.
By inspection the emitter voltage of Q12 is then determined to be
~ -4.93 V, which jibes with the measured drop across C7 of 4.87 V.

Danke,

--
Don, KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

[Don]

In sci.electronics.design piglet <erichpwagner@hotmail.com> wrote:

On 12/12/2020 6:19 pm, jlarkin@highlandsniptechnology.com wrote:
On Sat, 12 Dec 2020 17:54:08 -0000 (UTC), \"Don\" <g@crcomp.net> wrote:

In sci.electronics.design jlarkin@highlandsniptechnology.com wrote:
On Sat, 12 Dec 2020 07:56:15 -0000 (UTC), \"Don\" <g@crcomp.net> wrote:

<snip>

Why was the circuit designed to use a Callins in C7?

Was it designed that way?

That circuit was barely designed at all. What\'s it supposed to do?

Your question restates the gist of this thread.

How can you know the circuit was barely designed at all if you don\'t
even know what\'s it supposed to do?

Because it\'s full of trimpots and selected values. It was probably
futzed until it worked. What\'s it supposed to do?

My guess is it was some kind of analog synth VCO, inputs EFG are summed
and make the ramp, square and triwave outputs at jacks HDJ.

Dig the 3.6V D3 zener in the path, the 3.9Meg and 680R R19 R20 and the
kooky voltage follower Q3 Q11 Q4 - the unijunction Q2 is probably the
least nasty part of it all.

Thats why I used the word unsavoury!

Someone elsewhere mentioned how late designer John Simonton tried to use
as few parts as possible, presumably to keep the total price down. So my
earlier Woz analogy may be more spot on than first realized.
Woz\'s Breakout game design reportedly earned a bonus from Atari
because it kept its chip count below 120. Supposedly way down, somewhere
in the neighborhood of 50 chips, it\'s said. Legend has it although Atari
paid the bonus (to Steve Jobs) Atari didn\'t understand how Woz\'s circuit
worked.

Danke,

--
Don, KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

[piglet]

On 13/12/2020 3:52 pm, Don wrote:

In sci.electronics.design piglet <erichpwagner@hotmail.com> wrote:
On 12/12/2020 6:19 pm, jlarkin@highlandsniptechnology.com wrote:
On Sat, 12 Dec 2020 17:54:08 -0000 (UTC), \"Don\" <g@crcomp.net> wrote:

In sci.electronics.design jlarkin@highlandsniptechnology.com wrote:
On Sat, 12 Dec 2020 07:56:15 -0000 (UTC), \"Don\" <g@crcomp.net> wrote:

snip

Why was the circuit designed to use a Callins in C7?

Was it designed that way?

That circuit was barely designed at all. What\'s it supposed to do?

Your question restates the gist of this thread.

How can you know the circuit was barely designed at all if you don\'t
even know what\'s it supposed to do?

Because it\'s full of trimpots and selected values. It was probably
futzed until it worked. What\'s it supposed to do?

My guess is it was some kind of analog synth VCO, inputs EFG are summed
and make the ramp, square and triwave outputs at jacks HDJ.

Dig the 3.6V D3 zener in the path, the 3.9Meg and 680R R19 R20 and the
kooky voltage follower Q3 Q11 Q4 - the unijunction Q2 is probably the
least nasty part of it all.

Thats why I used the word unsavoury!

Someone elsewhere mentioned how late designer John Simonton tried to use
as few parts as possible, presumably to keep the total price down. So my
earlier Woz analogy may be more spot on than first realized.
Woz\'s Breakout game design reportedly earned a bonus from Atari
because it kept its chip count below 120. Supposedly way down, somewhere
in the neighborhood of 50 chips, it\'s said. Legend has it although Atari
paid the bonus (to Steve Jobs) Atari didn\'t understand how Woz\'s circuit
worked.

Danke,

Well in this design he didn\'t optimise enough. I can\'t see the need for
R14, but if needed for adjustment range R15 could be increased in
value to 200R. And R19 and R20 are providing an offset voltage of 1.5mV
but to a diff amp made from presumably unmatched and non-isothermal
Q6,Q7 and whose other input is derived from a vanilla zener and
follower. Even across minor room temperature changes the drift could be
horrible. I am baffled by that 1.5mV offset, bet you can just tie the
base to ground and save two resistors.

Also the polarity of C3 C4 C5 looks strange?

piglet

 

[Don]

In sci.electronics.design piglet <erichpwagner@hotmail.com> wrote:

On 13/12/2020 3:52 pm, Don wrote:
In sci.electronics.design piglet <erichpwagner@hotmail.com> wrote:

<snip>

My guess is it was some kind of analog synth VCO, inputs EFG are summed
and make the ramp, square and triwave outputs at jacks HDJ.

Dig the 3.6V D3 zener in the path, the 3.9Meg and 680R R19 R20 and the
kooky voltage follower Q3 Q11 Q4 - the unijunction Q2 is probably the
least nasty part of it all.

Thats why I used the word unsavoury!

Someone elsewhere mentioned how late designer John Simonton tried to use
as few parts as possible, presumably to keep the total price down. So my
earlier Woz analogy may be more spot on than first realized.
Woz\'s Breakout game design reportedly earned a bonus from Atari
because it kept its chip count below 120. Supposedly way down, somewhere
in the neighborhood of 50 chips, it\'s said. Legend has it although Atari
paid the bonus (to Steve Jobs) Atari didn\'t understand how Woz\'s circuit
worked.
Well in this design he didn\'t optimise enough. I can\'t see the need for
R14, but if needed for adjustment range R15 could be increased in
value to 200R. And R19 and R20 are providing an offset voltage of 1.5mV
but to a diff amp made from presumably unmatched and non-isothermal
Q6,Q7 and whose other input is derived from a vanilla zener and
follower. Even across minor room temperature changes the drift could be
horrible. I am baffled by that 1.5mV offset, bet you can just tie the
base to ground and save two resistors.

Also the polarity of C3 C4 C5 looks strange?

At some point there was a small ~ 1\" x 4\" scrap of paper included with
my documentation. It was an addendum, which noted how D4 was now 5.6 V
instead of 6.8 V. (A fact duly recorded on my paper schematic in ink,
but missing from the PDF, which was uploaded then shared with the
group.)
IIRC it also said Q6, Q7 were a matched pair. Of course, the scrap
of paper with irreplaceable information on it got misplaced.
Nonetheless, if you seek to match Q6 and Q7 to make the pair as
isothermal as possible, will this circuit do the job?

https://crcomp.net/paia/matcher.png

The D3 kludge is easy enough to grasp. But R19 and R20\'s eccentricity is
a little too far out for me. Simonton\'s next generation VCO removes some
unsavoriness:

https://crcomp.net/paia/4720.png

Danke,

--
Don, KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

[bruce bowser]

On Friday, December 11, 2020 at 11:46:51 PM UTC-5, Steve Wilson wrote:

John Larkin <jlarkin@highland_atwork_technology.com> wrote:

What use is a 300 uF non-polar \'lytic?

Motor Start Capacitor:

NTE Electronics MSC125V270 Series MSC Motor Start AC Electrolytic
Capacitor, Two 0.250\" Quick Connect Terminals, 270-324 µF Capacitance,
110/125V
CDN$ 15.92 FREE Delivery

https://tinyurl.com/y5uwh2gz

(https://www.amazon.ca/NTE-Electronics-MSC125V270-Electrolytic-
Capacitance/dp/B007Z7MBJY/)
But the Callins is 25 volts.
So? You didn\'t specify. You said \"What use is a 300 uF non-polar \'lytic?\"

I imagine the Amazon cap could be used in audio applications. It may even
have lower distortion. It is certainly intended to carry amps of current,
and might even be used in high power aplications where the original
collins would fail.

The Amazon is brand new, where the collins has probably dried out by now.

Then there are other liquor glasses out there, like the shot glass, the champagne glass, martini glass, rocks, coupe, whiskey sour, highball, copper mug, brandy glasses, cordials, the Irish coffee cup, champagne glasses. You can order all online, now.

 

[Tauno Voipio]

On 12.12.20 22.14, Don wrote:

In sci.electronics.design Tauno Voipio <tauno.voipio@notused.fi.invalid> wrote:
On 12.12.20 19.34, jlarkin@highlandsniptechnology.com wrote:

snip

Was it designed that way?

That circuit was barely designed at all. What\'s it supposed to do?


Agreed.

There is a voltage-controlled UJT sawtooth generator, with
outputs sent to three places:

- direct output,

- a differential pair-rectifier to cut it at the
middle for a (maybe) symmetric triangle,

- a Schmitt-trigger to create a variable width pulse

There is plenty of opportunity for improvement even when
using the block diagram (and forgetting the UJT).

You seem to know what you\'re talking about.

Although its ramp and triangle outputs are now restored, the Schmitt
trigger\'s still a work in progress. It\'s (manually transcribed from a
PDF and as typo-free as possible) Design Analysis is shown below. The
last paragraph in the analysis leads me to believe the Callins capacitor
was plausibly used by design.

DESIGN ANALYSIS

The central feature of the 2720-2A VCO is the self-zeroing, summing
voltage to current converter comprising of IC-1, Q1 and associated
components. Unlike the more conventional inverting summer, the feed
back voltage does not come directly from the output of the amplifier
but rather from the emitter of the current source transistor Q1. In
operation positive voltages applied to one or more of the summing
resistors (R1 - R3) force the output of the amplifier to go to
whatever negative voltage is necessary to make the same voltage
appear at both the inverting and non-inverting inputs of the op amp.
Feedback circuits are always a balancing act and the balanced point in
any linear operational amplifier circuit is reached when the two inputs
are at equal voltages. Since in this case the non-inverting input is
grounded (0v.) the inverting input must also go to zero volts.

Since the base emitter junction of Q1 is inside the feedback loop of
the summing amplifier, both the natural non-linearities and constant
voltage drop of the junction are eliminated from the response of the
current source. Both sets of resistors that serve as emitter resistances
for the current source (Range trimmer R7 in series with R6 both
paralleled by R4) terminate at ground and a virtual ground so that for
zero control volts input the source must generate zero current.

The output of the current source charges capacitor C1 which in
conjunction with Unijunction Transistor (UJT) Q2 forms a relaxation
oscillator. As increasing voltages are applied to the control inputs,
the current supplied by Q1 increases causing C1 to charge more rapidly
thereby increasing the frequency of the oscillator.

The ramp waveform that appears across C1 is applied to the input of the
darlington emitter follower consisting of Q4 and Q11. The high input
impedance of this emitter follower is important in presenting
negligible load to the timing capacitor C1. A second emitter follower Q4
in conjunction with zener diode D3 performs a level shift so that the
ramp is transposed to slightly above ground potential while a third
emitter follower (Q5) provides a low output impedance buffer to couple
the signal to the rest of the waveforming circuitry.

The ramp waveform is used three ways. First, it is applied to the
voltage divider string consisting of R11, R24, R23 and R22. Between R11
and R24 the string is capacitively coupled through C5 directly to the
\"RAMP\" output jack J1 where it becomes available as a signal source.

Secondly, the ramp is applied to the Schmitt trigger composed of Q9 and
Q10. A Schmitt trigger has a low output or a high output depending on
whether the input voltage is above or below a pre-set design level. As
the ramp input to the trigger begins to rise the output remains low
until the voltage exceeds this level and then abruptly changes to the
high state. The output of the trigger, then, is a rectangular pulse at
exactly the frequency of the ramp input. By varying the amplitude of the
ramp you regulate the duration of the pulse by changing the relative
point at which the trigger changes state.

Finally, the ramp is applied to the input of the differential pair Q6
and Q7. In the differential configuration the voltage at the collector
of Q7 is in phase with the input ramp and the voltage at the collector
of Q6 is inverted. The diodes D1 and D2 \"select the higher of the two
collector voltages and apply it to the base of emitter follower Q8.
During the lower half of the input ramp\'s excursion Q6\'s collector
voltage is higher and that section of the ramp is presented in an
inverted form to the base of Q8. There is a slight rounding at the
bottom of the wave during the cross over between Q6 and Q7 and a slight
pip at the top during the ramp \"flyback\" but neither of these
imperfections are audibly noticeable.

The most voltage sensitive portions of the circuit are powered from the
simple series voltage regulator consisting of zener reference diode D4
and pass transistor Q12. Less critical parts of the circuit are powered
by the decoupling networks R33/C6 in the positive supply line and
R35/C8 in the negative supply.

Danke,

Hello Don,

I made a LTspice model of the thing:

Version 4
SHEET 1 3144 724
WIRE 848 -320 -864 -320
WIRE 1008 -320 848 -320
WIRE 1472 -320 1008 -320
WIRE 1728 -320 1472 -320
WIRE 1888 -320 1728 -320
WIRE 2064 -320 1888 -320
WIRE 2496 -320 2064 -320
WIRE 2624 -320 2496 -320
WIRE 2912 -320 2624 -320
WIRE 848 -288 848 -320
WIRE 1472 -272 1472 -320
WIRE 1728 -272 1728 -320
WIRE 1888 -240 1888 -320
WIRE 2912 -224 2912 -320
WIRE -272 -144 -352 -144
WIRE -48 -144 -192 -144
WIRE 16 -144 -48 -144
WIRE 192 -144 96 -144
WIRE 304 -144 192 -144
WIRE 432 -144 304 -144
WIRE 592 -144 432 -144
WIRE 1008 -144 1008 -320
WIRE 1472 -144 1472 -192
WIRE 1520 -144 1472 -144
WIRE 1600 -144 1584 -144
WIRE 1632 -144 1600 -144
WIRE 1728 -144 1728 -192
WIRE 1728 -144 1696 -144
WIRE 2064 -144 2064 -320
WIRE 2496 -144 2496 -320
WIRE 2624 -144 2624 -320
WIRE 304 -96 304 -144
WIRE 848 -96 848 -208
WIRE 944 -96 848 -96
WIRE 1600 -96 1600 -144
WIRE 2000 -96 1600 -96
WIRE 2912 -96 2912 -144
WIRE 3024 -96 2912 -96
WIRE 192 -64 192 -144
WIRE 1472 -64 1472 -144
WIRE 1728 -64 1728 -144
WIRE 2912 -64 2912 -96
WIRE -48 -32 -48 -144
WIRE 1008 -16 1008 -48
WIRE 1184 -16 1008 -16
WIRE 1344 -16 1264 -16
WIRE 1408 -16 1344 -16
WIRE 1888 -16 1888 -160
WIRE 1888 -16 1792 -16
WIRE -544 0 -672 0
WIRE -352 0 -352 -144
WIRE -352 0 -464 0
WIRE -272 0 -352 0
WIRE 2064 0 2064 -48
WIRE 2160 0 2064 0
WIRE -112 16 -208 16
WIRE 1008 16 1008 -16
WIRE 2624 16 2624 -64
WIRE 2672 16 2624 16
WIRE 2768 16 2752 16
WIRE -272 32 -320 32
WIRE 432 32 432 -144
WIRE 848 32 848 -96
WIRE -864 64 -864 -320
WIRE -672 64 -672 0
WIRE 1344 64 1344 -16
WIRE 1472 64 1472 32
WIRE 1728 64 1728 32
WIRE 1888 64 1888 -16
WIRE 2064 64 2064 0
WIRE -320 80 -320 32
WIRE -48 80 -48 64
WIRE 368 80 -48 80
WIRE 592 80 592 -144
WIRE 2624 80 2624 16
WIRE 2912 80 2912 16
WIRE 192 112 192 16
WIRE 528 128 432 128
WIRE 1008 128 1008 96
WIRE 1104 128 1008 128
WIRE 2496 128 2496 -64
WIRE 2560 128 2496 128
WIRE 2768 128 2768 16
WIRE 2848 128 2768 128
WIRE 1008 160 1008 128
WIRE -48 176 -48 80
WIRE 128 176 -48 176
WIRE 1472 176 1472 144
WIRE 1600 176 1472 176
WIRE 1728 176 1728 144
WIRE 1728 176 1600 176
WIRE -864 192 -864 144
WIRE -672 192 -672 144
WIRE -672 192 -864 192
WIRE -480 192 -672 192
WIRE 848 192 848 96
WIRE 2496 192 2496 128
WIRE 1344 208 1344 144
WIRE 1600 208 1600 176
WIRE 1888 208 1888 144
WIRE 2064 208 2064 144
WIRE 2624 208 2624 176
WIRE 2912 208 2912 176
WIRE 2912 208 2624 208
WIRE -480 224 -480 192
WIRE -864 240 -864 192
WIRE -672 240 -672 192
WIRE 592 240 592 176
WIRE 784 240 592 240
WIRE 2768 240 2768 128
WIRE 2912 240 2912 208
WIRE -48 256 -48 176
WIRE 1008 256 1008 240
WIRE 1248 256 1008 256
WIRE 1008 272 1008 256
WIRE 592 288 592 240
WIRE 1248 352 1248 256
WIRE 2496 352 2496 272
WIRE 2496 352 1248 352
WIRE 1008 400 1008 352
WIRE 2768 400 2768 320
WIRE 2912 400 2912 320
WIRE -672 432 -672 320
WIRE -48 432 -48 320
WIRE -48 432 -672 432
WIRE 192 432 192 224
WIRE 192 432 -48 432
WIRE 848 432 848 288
WIRE 848 432 192 432
WIRE 1600 432 1600 288
WIRE 1600 432 848 432
WIRE -864 496 -864 320
WIRE 592 496 592 368
WIRE 592 496 -864 496
FLAG -320 80 0
FLAG 304 -96 0
FLAG -480 224 0
FLAG 1008 400 0
FLAG 1104 128 ramp
IOPIN 1104 128 Out
FLAG 2768 400 0
FLAG 2912 400 0
FLAG 3024 -96 pulse
IOPIN 3024 -96 Out
FLAG 1344 208 0
FLAG 1888 208 0
FLAG 2064 208 0
FLAG 2160 0 triangle
IOPIN 2160 0 Out
SYMBOL Opamps\\\\opamp -240 -48 R0
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SYMATTR Value 2N3906
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TEXT -288 112 Left 2 !.lib opamp.sub
TEXT -360 288 Left 2 !.tran 30m
TEXT 1816 408 Left 2 ;2720-2A model, some components guessed.

There was no mode for an UJT, so I made an 2N2646.

2N2646.asy:

Version 4
SymbolType BLOCK
LINE Normal 1 76 16 80
LINE Normal 1 85 1 76
LINE Normal 16 80 1 85
LINE Normal 48 88 48 112
LINE Normal 16 88 48 88
LINE Normal 16 96 16 16
LINE Normal 48 24 48 0
LINE Normal 16 24 48 24
LINE Normal 1 80 -16 64
WINDOW 0 93 35 Bottom 2
WINDOW 3 110 85 Top 2
SYMATTR Value 2N2646
SYMATTR Prefix X
SYMATTR ModelFile 2N2646.SUB
PIN -16 64 BOTTOM 8
PINATTR SpiceOrder 1
PIN 48 112 RIGHT 8
PINATTR SpiceOrder 2
PIN 48 0 RIGHT 8
PINATTR SpiceOrder 3

Model from the Net, probably by the late Jim Thompson:

..SUBCKT 2N2646 1 2 3
DE 1 4 EMITTER
VE 4 5 DC 0
HVE 6 0 VE 1K
RVE 0 6 1MEG
BBB 5 7 I=0.00028*V(5,7)+0.00575*V(5,7)*V(6)
CBB 5 7 35P
*RB1 7 2 38.15 RMOD
*RB2 3 5 2.518K RMOD
*.MODEL RMOD R TC1=.01
RB1 7 2 38.15
RB2 3 5 2.518K
..MODEL RMOD R TC1=.01
..MODEL EMITTER D (IS=21.3P N=1.8)
..ENDS 2N2646

---

There are many components without types or values, so
I had to guess them.

There are plenty of issues, beginning with the slot in the
triangle at the positive tip, die to the retrun time of
the ramp signal.

The output capcitors are left out of the simulation, I do
not have a mode for a reversed electrolytic.

--

-TV

 

[Michael Terrell]

On Saturday, December 12, 2020 at 12:24:00 PM UTC-5, John Larkin wrote:

The old bakelite Black Beauty film (or maybe paper?) caps are highly
prized/priced because some people can hear the difference.

If I paid $25 for a 0.022 uF cap, I bet I could hear the difference.

I wonder how many of these sorts of things are Chinese fakes.

Black Beauties were oil filled paper capacitors. They were supposed to outlast regular paper caps. Many went bad on the shelf.

 

[Don]

In sci.electronics.design Tauno Voipio <tauno.voipio@notused.fi.invalid> wrote:

<snip>

There are many components without types or values, so
I had to guess them.

There are plenty of issues, beginning with the slot in the
triangle at the positive tip, die to the retrun time of
the ramp signal.

The output capcitors are left out of the simulation, I do
not have a mode for a reversed electrolytic.

Fantastic! Thank you for all of your hard work. It will take me a few
days to digest it all.
Meanwhile, my pertinent notes on UJT models are available online, at
the link shown below. Among other things, it contains a 2013 usenet
thread where the late Jim Thompson compares the UJT model you used with
a couple of others.

https://crcomp.net/paia/ujt.php

Danke,

--
Don, KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.