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Selmer Buzztone transistors?

Started by vizcities, December 06, 2020, 04:39:56 PM

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vizcities

I'm building a modded one of these for my Barrett-obsessed brother, but the original transistors (2n2613) are unobtainium &, though I'm comfy swapping in other PNP Ges, I'm not quite certain what hFe and leakage I should be pursuing. I've heard the circuit's not far off from the Maestro FZ-1A (which uses 2n2614s, according to Tagboard FX), which is a place to start. That said, I wanted to get a sense of what might worked for you fine folks before I go shopping. Any thoughts/suggestions?

midwayfair

I used 2n229s from smallbear in a negative-ground build:

https://www.madbeanpedals.com/forum/index.php?topic=29653.msg287123#msg287123

The gain on them is fairly low, in the 50s, and they are average or low ground. However, the first transistor needs to be REALLY low gain, low enough in fact that I had to put the first transistor in backwards to get it to bias.

The pedal runs on low voltage and there's no clever filtering or anything going on, plus there's enough gain in the circuit to cause motorboating. I would try to keep the leakage low.

Breadboard the circuit, you will absolutely want to adjust the biasing resistors rather than hunting for the perfect transistors to work properly in the thing.

Don't use the layout I posted as-is, it actually needs a voltage regulator instead of just a zener drop or else it'll feedback ...