[sdiy] VCO reference voltages

[David G. Dixon]

> You can reduce the value of the coarse tune summing resistor (and tuning
> pot if necessary to avoid loading by the lower value summing resistor)
> to get the same tuning range from a lower reference voltage.

Yeah.  You don't have to rub it in!  ;^)

> On another note, I've been wondering if it would be acceptable to use an
> inverting op amp circuit  to generate the negative reference voltage
> from the positive reference. I guess as long as the offset drift specs
> for the op amp are suitable then it will be ok...

People do it all the time for various applications.