[sdiy] Thought experiment...

[harrybissell]

It would also reject the CV itself...   :^(

H^) harry

D A F wrote:

> Hi all, I was taking a look at the schematic for the music from outer
> space VCO board, when I got an idea concerning a possible way to
> elliminate tempcos from VCO's.  I'm sure someone has probably thought
> of this (like 40 years ago) but in any case, here goes...   If you had
> a quad of matched transistors on a single substrate (such as in the
> new THAT 300 series), or at least two thermally coupled pairs,
> couldn't you send one pair a positive-going CV and the other pair a
> negative-going CV and then send the two outputs to a differential
> amplifier, such that only the difference signal would be amplified.
> This would elliminate the change in current with temperature from the
> final output, because it would be equal in both pairs, assuming
> perfectly matched and thermally-coupled devices, and the diff amp
> would 'ignore' it.  Any thoughts?  Dave