Duocast - Transistor?

[playedincanada]

Alright,

So I've built this pedal multiple times. I've never had an issue like this, so I've come here to see if anyone can think why the pedal would act a particular way.

Everything works as it should.

Until you put it into 27V Mode.

Then, if the gain is up pretty high for the 1st side (which if I'm not mistaken is the Germanium Transistor), it will self-oscillate, sounding as if a "glitch mode" has been activated.

I think I have read elsewhere that if the hfe is too high for the transistor this causes these kinds of problems. It sounds fine in the regular 9V mode and doesn't do the osccillation thing then.

It's not present if you have the other channel engaged (including the silicon transistor)

Any insight would be greatly appreciated!

- Matt

 

[jwin615]

Depending on the transistor, you may be exceeding some voltage spec. Vce and or Vbe

 

[playedincanada]

I also saw somewhere some specs were posted.

Do we have a definite answer as to what they are? I've always just worried about the hfe being somewhere between like 60 and 100, but I think someone had mentioned leakage as well?