[sdiy] germanium vco experiment

[Harry Bissell]

I think you hit the nail on the head, lower forward voltage drop, terrible leakage. Maybe that's
why they aren't used anymore :^)

Better to replace that "half- at ssed replacement for the vacuum tube" with the version that really
replaced the vacuum tube.. uhhh... silicon

The 'mojo' of the Germanium transistor is the lower B-E drop... you can make a fuzzier fuzzbox. OTOH
you can do the same with shottky diodes

H^) harry


----- Original Message -----
From: dan snazelle <subjectivity at hotmail.com>
To: synthdiy diy <synth-diy at dropmix.xs4all.nl>
Sent: Tue, 16 Aug 2011 17:06:42 -0400 (EDT)
Subject: [sdiy] germanium vco experiment

over the last few weeks i have been working entirely with transistor based designs....i have bought up some books on transistors (always looking for more if you want to sell or recommend any ;)
and I have tried finding as many schematics as i can of discrete synths or discrete sections.


today on the breadboard i was fooling around with the ARP axxe VCO....

just for fun I decided to swap out some of the transistors with Germanium transistors.... (i have been buying them up for a distortion project)

well it was one of the most horrible things I have ever heard.....for some reason (maybe due to the lower turn on voltage?) the VCO, when I had replaced the PNP transistor with a low leakage germanium (soviet)
of low hfe (Around 75) , well it would only hit the high notes (and the high notes sounded normal)


every time i tried bringing the pitch knob down low, the entire waveform would turn to scratchy hissy noise.....it was interesting for its novelty, but certainly not a success....

it got me wondering if such a circuit COULD work if the values were adjusted.....or if germanium transistors simply dont have the range of a silicon


I havent had much luck finding info on the differences between germanium and silicon transistors (except that germaniums have a lower turn on voltage and more leakage) because very few transistor 
books mention them at all.






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-- 
Harry Bissell & Nora Abdullah 4eva