[sdiy] VCO reference voltages

[Stewart Pye]

Hi David,

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.

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...

Regards,
Stewart.


David G. Dixon wrote:
> The other downside of regulating rail voltages for the tuning pots is that,
> because regulators only regulate to within 1 or 2 volts of the rails, using
> regulated voltages for the rails will limit the range of the pots,
> particularly in a +/-12V system.  This is not necessarily a problem on the
> upper end, but it could be on the lower end unless the VCO has an LFO range
> switch.
>
>