Anything I can do with hfe 25 silicon?

[Kesh]

I have some 2n2369s, which I'm guessing had the usable hfe ones removed as they run from 19 to 37. Anyway, they cost me nothing.

They look pretty, with gold legs, but are they any use beyond ornaments? Could I darlington them?

[LucifersTrip]

I have some 2n2369s, which I'm guessing had the usable hfe ones removed as they run from 19 to 37. Anyway, they cost me nothing.

They look pretty, with gold legs, but are they any use beyond ornaments? Could I darlington them?

yes...or use bc or be as diodes



there's definitely some circuits that use very low hfe silicon, but I think I only have schematics for low gain ge

you can try this type of Fuzz Face variant, with the output right off the collector:
http://www.luciferstrip.com/fuzz/fuzzface-fy2-mod-variable.jpg

remember, use a small vol pot and Q2C voltage is < 4.5v

[Kesh]

Thanks. I was also thinking of using them as clipping diodes, but can I expect anything different from regular Si diodes in terms of clipping shape?

I had a vague idea to try and design some three stage version of the two stage fuzz face with them.

[smallbearelec]

Pls see my notes:

https://www.smallbearelec.com/HowTos/GeDarlingtons/GeDarlingtonPairs.htm

I have done many hybrid germanium-silicon darlington pairs. It is literally a way to make silk purses out of sows' ears.

[midwayfair]

You can also make a percolator with an Si in Q1 instead of Germanium. Use silicon diodes too to keep the output up and costs down.

[roseblood11]

You can also make a percolator with an Si in Q1 instead of Germanium. Use silicon diodes too to keep the output up and costs down.

Doesn't the harmonic percolator use a pnp transistor for Q1?

[Kesh]

Pls see my notes:

https://www.smallbearelec.com/HowTos/GeDarlingtons/GeDarlingtonPairs.htm

I have done many hybrid germanium-silicon darlington pairs. It is literally a way to make silk purses out of sows' ears.

This is great, thanks.

[seedlings]

Low gain can have the same output as high gain, just takes a larger input signal to get there.  You can probably use that as Q3 of a 3 transistor overdrive like the Vulcan.  Any schematic with a large voltage divider before a transistor- substitute no divider plus your transistor.

CHAD

[Kesh]

Low gain can have the same output as high gain, just takes a larger input signal to get there.

Roughly, gain is the increase from input to output, so is defined as being independent of the input level.

[seedlings]

Low gain can have the same output as high gain, just takes a larger input signal to get there.

Roughly, gain is the increase from input to output, so is defined as being independent of the input level.

Gain is the ratio of output to input.

One circuit has a gain of 100 with a 9V power supply so it takes .09V input to get 9V output.

Another circuit has a gain of 20 with a 9V power supply so it takes .45V input to get 9V output.

Both can give you 9V output.

CHAD

[Kesh]

Yes, we all know that. Not quite sure what you're trying to add here.

The voltage gain of a transistor stage is not the same as hfe current gain, and is only tenuously related to it

[seedlings]

Yes, we all know that. Not quite sure what you're trying to add here.

The voltage gain of a transistor stage is not the same as hfe current gain, and is only tenuously related to it

Admittedly, I'm not knowledgeable enough to help in anything beyond generalities.  My apologies.   

I had been reading this thread http://www.diystompboxes.com/smfforum/index.php?topic=94883.msg820126#msg820126 and thought (perhaps mistakenly) that your low hfe transistors might still be usable in the last stage of an overdrive without adding much gain, just flavor.  At the end of a vulcan-type overdrive the voltages are already large from the previous stage.  Perhaps too simple and obvious a suggestion, but it's all I had to offer.

CHAD