Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Effects => Topic started by: jeff on September 20, 2013, 12:10:29 pm
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I've been playing around with a tube screamer curcuit, and it sound pretty good. I've heard that Ge doides work even better a far as a softer clip. I don't have any Ge diodes but I've come across some Ge NPN transistors. I remember seeing somewhere that you can wire a transistor a a doide but don't remember how.
Anyone know how to use a transitor as a diode?
Thanks
Jeff
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That's a great way to use leaky Ge transistors. From what I've read, you can use either base-emitter junction or base-collector junction. Just use a DMM set to diode mode to find the correct polarity. Chromesphere shares his method here, which is a little different: Using a Transistor as a Diode (http://www.youtube.com/watch?v=bF1zTsm-u9Y#ws) - he twists together the base & collector leads, uses those as one side of the diode, and uses the emitter as the other side. On the PNP Ge tranny he tested with his method, the B&C leads were cathode/negative side of the diode and the E lead was anode/positive. Your NPN transistors might be the opposite?
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Humm, you tie the source & gate tied together when using a mosfet as a clipping diode so w/out testing it is similar to saying that the emitter and base would be tied together. But in this case I'm guessing that Jeff would use a PNP tranny for this? Why not just use ordinary 1n34a Ge diodes or similar? It would be much less costly and why use up expensive & good Ge tranny's for such a simple task? There should not be any big sound differences or extra mojo in using Ge trannies in place of Ge diodes here. Then again you never know unless you try it? Measure the forward voltage drops of all before you insert them into the circuit either way. This is more important than most of those other factors, all things being equal.
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I would think that using LEDs as clippers would make more sense as experimental parts? you can find tons of them in old stereo gear that people throw out. there is no muss or fuss with 3 legs as with the sneaky little trans goblins. :icon_biggrin: