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Vintage threads from the first ten years
Swapping c & e on a transistor
 6/26/2000 10:35 PM |
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Stuart | Swapping c & e on a transistor This relates to the input transistor on a Voodoo Vibe, which is a BC549 (Si NPN). R.G. might remember me bugging him about this a few months ago, because I couldn't understand why the emitter would be at a higher voltage than the collecter. We decided it must be a dirty trick, using a transistor with a different pinout. Anyway, I've just been playing around with it and now I'm confused. Swapping in another BC549 in the same orientation, I measured the following voltages: c=2.73V, b=3.11V, e=6.99V Reversing the transistor to make it "correct", I read the following: c=6.99V, b=3.12V, e=2.74V I'd never tried connecting transistors back to front, so it never occurred to me that they would bias the same. The pedal works and sounds the same in both cases, but surely you wouldn't design it like that? Any ideas? I'm still inclined to think that it's an assembly mistake & it was inserted the wrong way... |
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| R.G. Here's what's going on. |