forgive me for my stupidity but...

Christian Hofmann chris at scp.de
Fri Nov 5 11:37:41 CET 1999


On Fri, 5 Nov 1999 10:18:08 +0100 (BST)
"Mark Cornell" <cornellm.student at ringwoodschool.demon.co.uk> wrote:

> So what are these Tempco resistors used for in
> Synth DIY circuits?

Um, it's no big thing. It just for those oscillators, which you don't
really need at all to make a sound... ;-)


To be even more precise: for the usual 1 Volt per octave characteristic
you need a circuit that generates an exponential function. 
It's generally based around the exponential Ub-to-Ic property of a
transistor. Sadly this relation is severely temperature dependant, so
you need a precise way to compensate that effect in order to have a
sufficiently stable pitch. 
That's where a tempco resistor comes in. If you can find one, that is...

Christian



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