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Need assistance with Russian to help decode Soviet ICs
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Author Need assistance with Russian to help decode Soviet ICs
decaying.sine
I am building a Polivoks filter using original Russian parts. I purchased them from Evita online and they showed up in a little pile with no way for me to identify the IC's. I posted a photo below to see if anyone could translate for me? The two IC types are: KR140UD12 and KR140UD8B.

I appreciate your help figuring this out. Thanks!

decaying.sine
I think I figured it out but verification would be great.
The KR140UD8B is the IC on the left and the KR140UD12 is the one on the right.

I checked out the original Russian schematic and that seems to help.

If it blows up, they were cheap ICs anyways hihi

e-grad
The left one reads: 140UD; right one: UD1208 or UD120V.

Can't figure whether the last one is an '8' or an cyrillic 'B' which would be a latin 'v' (or even 'w' in german transcription).
boothnavy
I built one this way too, more or less, and haven't quite got it working 100%. Would love to compare notes if you get yours fully operational.

decaying.sine
Awesome. Let's troubleshoot together. Mine is completely done now. I didn't have a chance to test it other than the magic smoke test.

I am watching Lost with my lady love and then I'll take some snapshots as a start.
Bergfotron
decaying.sine wrote:
I checked out the original Russian schematic and that seems to help.


How can it be a filter without capacitors in the circuit? The caps could be inside the ICs of course, but is that likely?
boothnavy
Bergfotron wrote:

How can it be a filter without capacitors in the circuit? The caps could be inside the ICs of course, but is that likely?


From Marc Bareille's web site:

Unlike most of Voltage controled analog filters who use a combination of a fixed capacitor with a variable resistor element ( OTA, opto,etc..) the filter core here is just a pair of programmable low power operational amplifiers ( PLPOA?). At first sight, it look like a classic SVF but with a difference: there is no capacitors ! CV modulations are applied on the current setting pin (Iset) to reduce or increase the GainBandwith of the aop who act as a variable time constant RC element. It is a 12dB filter. Sound as well. A bit wild at extreme Q, remind a little bit the Korg MS20 on this point . Frequency modulation on CV inputs work well with this filter!
Bergfotron
boothnavy wrote:
Bergfotron wrote:

How can it be a filter without capacitors in the circuit? The caps could be inside the ICs of course, but is that likely?


From Marc Bareille's web site:

Unlike most of Voltage controled analog filters who use a combination of a fixed capacitor with a variable resistor element ( OTA, opto,etc..) the filter core here is just a pair of programmable low power operational amplifiers ( PLPOA?). At first sight, it look like a classic SVF but with a difference: there is no capacitors ! CV modulations are applied on the current setting pin (Iset) to reduce or increase the GainBandwith of the aop who act as a variable time constant RC element. It is a 12dB filter. Sound as well. A bit wild at extreme Q, remind a little bit the Korg MS20 on this point . Frequency modulation on CV inputs work well with this filter!


There has to be a C somwhere if it's going to be an RC circuit. On-chip capacitors are typically very small (tens of pF maybe) so in that case the R part has to be really large or else the cutoff frequency will not be low enough.
decaying.sine
Not sure about integrated caps in the IC, but besides the 10uF electrolytics off the power supply, the only caps on mine are two .47 uF polyester film caps.
Neutron7
if the gain bandwidth is decreased with the "current controlled op amp crappiness" you would not need capacitors, that is very clever!
ultrashock
Bergfotron wrote:
How can it be a filter without capacitors in the circuit? The caps could be inside the ICs of course, but is that likely?
the trick is that THERE ARE caps inside the К140УД12 which is not just the ordinary soviet clones of common op-amps but act alike OTA as well and the caps are in the internal pins for frequency correction (smth. that called 'balancing').
Unforntunately, there are no internal schematic diagram for this chip over the internet - everything was described mostly in paper documentation (due to military secret or so d'oh!)
Thus it is a good example of using undocumented possibilities of chip smile
Achtung! К140УД12 and К140УД1208 has different pinouts
КР140УД8 acts more like the ordinary op-amp.
Tim Stinchcombe
ultrashock wrote:
Thus it is a good example of using undocumented possibilities of chip
I'm certain I have seen the method in one of the really old books that I have. It came up on Synth DIY a few years ago, and I couldn't find the reference then - perhaps I shall have a more concerted attempt at finding it again.
daverj
From what I've read, the D8B is basically a clone of the uA740, and the D12 is a clone of the uA776. The uA740 is similar to the more popular uA741, except it had FET inputs instead of bipolar. The uA776 has the same pinouts as the uA740 and uA741, except pin 8 accepts a current which changes the internal characteristics of the amp.

Here's the uA776:

decaying.sine
I'll post a pic of my populated board tonight. It's passing audio but not filtering. It's certainly not self-resonating like a champ either. I don't expect it to be a perfect sine, but mine doesn't seem to be doing too much at high Q.

I need to double check the schematic. The pic on Marc's site showing a cartoon overlay on the PCB seems to have the 2N3904 mounted backwards. I checked the schematic and double checked the 2N3904 pinout, and I believe if you use this tranny then it needs to be rotated 180 degrees. This meant that my KT315G was originally in backwards as well in addition to collector and base needing to be swapped if you use the vintage transistor. After changing all that I still got nothing.

I think I am going to try to replace the russian chips with newer equivalents to see if I can get it to work with those first.
boothnavy
I have the same issue! funny. maybe it is the pinouts of the russian chips?

let me know if putting modern chips in works.
ultrashock
try this one:
these goes to 140UD8

and this seems to be 140UD12

the KP at the beginning means different pinout
decaying.sine
Just found this thread at E-M. The 2N3904 does seem to be inaccurate on the graphic. Like sneakthief said, it'll be incorrect for most 2N3904 that you will encounter.

http://electro-music.com/forum/post-267945.html

That doesn't help me because I used the KT315G.

I'm trying to find some modern replacements in my bins to see if I can get it to work without the vintaj.
boothnavy
sine,

Dave Brown just got mine up and running! he said it was because the transistor was in wrong... I used the pinout from the guy in latvia, prolly the same place you got yours, he must have been wrong...

try shifting the leads around and see if it works.
decaying.sine
That's great news. Any chance you could take a couple pics?

Did you check to see if self-resonates? That's always one of the first things I check on my soft-scope to see how things are going.
boothnavy
I'll take some pics and do some tests when I get it back.
decaying.sine
Awesome. You know what I just realized too. My distro board is malfunctioning. I am getting a short or something when two modules are plugged in. I have to check into that. Mine could have been working all along very frustrating

I'll check my pics with yours and then go from there.
phutureboy
Hi Guys, would anyone know where to purchase 2 К140УД1208 and 1 УД608 ? as found in the Polivoks VCF
Trachea
I've seen them on evilbay. Try searching for KR140UD12 and KR140UD8B, the english version of the designations. Also, Erica Synths has the -12.
flagada
I bought mine here: https://www.evita.lt/en/
One of them was a metal can. I also bought the KT315G transistor there.
phutureboy
Thanks guys !
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