Russian germanium transistors?

[DUCKFACE]

hello
i found a pocket of NOS russian transistors as follow:

MP40 - МП40
https://eandc.ru/catalog/detail.php?ID=12285
western analog EFT306, EFT307


MP25A - МП25а
https://eandc.ru/catalog/detail.php?ID=12275
western analog 2N189, 2N190, 2SB136, 2SB136A.


MP37A - МП37а
https://eandc.ru/catalog/detail.php?ID=12281
western analog 106NU70, 2SD37, 2SD75A


the question is what can i build with them ?

[antonis]

Almost any kind of Fuzz..

And some of them as clipping diodes..

[mozz]

Russians transistors will usually measure the low end of what they say the gain is. May work in a fuzz. If they are cheap enough, try them out.

[Elektrojänis]

Russians transistors will usually measure the low end of what they say the gain is. May work in a fuzz. If they are cheap enough, try them out.

I wonder if anyone has tried using two germanium transistors with too low gain in a darlington configuration to replace what would be just one in a standard fuzz circuit?

[antonis]

I wonder if anyone has tried using two germanium transistors with too low gain in a darlington configuration to replace what would be just one in a standard fuzz circuit?

To simulate a Si BJT of high leakage current..??
(and perhaps a slightly lower V_BE..)

[percyhornickel]

I have built a few circuits with germanium transistors. A Fuzz Face, Tone Tender MKII (according many Erik Vincent advices) and NPN Rangemaster (AC127)...   ...love all of them, great sounds..   ..a must have DIY circuits

You need to measure the leakage first to decide what to do with them later.

Percy

[DUCKFACE]

i like the idea of darlington configuration anyone does it before ?

[iainpunk]

my first fuzz that i actually liked and considered a serious pedal, was a single stage of Ge and Si transistors in a Sziklai pair. ge and ge together was too leaky, but having a Si driving a Ge was great. it was quite a low gain fuzz, almost overdrive levels of gain, but it made me really happy.

using a darlington or sziklai pair in a fuzz face isn't really that great, as the leakage makes it that the collector resistor needs to be small and thus the gain low.

cheers

[idy]

you can use the search function, darlington fuzz, darlington Ge, etc. There are a few threads.

[DUCKFACE]

what do you prefer? Darlington or Sziklai ?

[iainpunk]

In Si transistors, sziklai sounds a bit more open and raspy, where Darlington is a little bit smooter, in overdrive pedals i built.

This is because when a sziklai single ended gain stage goes in to saturation, it has a harder knee than a Darlington has. This comes drom the 2nd transistor going in to cutoff, instead of saturation, which is always harder.

Cheers

[mdcmdcmdc]

i like the idea of darlington configuration anyone does it before ?

Look up any of the different versions of the Tone Bender MKIII or MKIV; it's a fantastic sounding circuit that uses a darlington pair in the first stage.