[diy] moog VCOs

[Tom May]

"Tony Allgood" <oakley at techrepairs.freeserve.co.uk> writes:

> Are there any differences in using the expo transistors the other way
> round?

Connect the CV to the transistor sinking the output current and the
output current increases with increasing CV.  Connect the CV to the
other transistor (the one in the op-amp feedback loop) and output
current decreases with increasing CV.

Note that the ASM-1's CV is inverted so it is connected the second
way.

> That is; in most of my previous expos, I sink the VCO/VCFs
> current in the transistor that has the control voltage applied. This is
> the same as the Formant and the ASM-1 I think. But the minimoog VCO uses
> the second one, with the op-amp's feedback going to the first. At first
> glance, I cannot see any advantage in doing this, but am I missing
> something?

fTom.