[sdiy] How to make a continuously variable wave LFO or VCO

[Dave Manley]

Paul Schreiber wrote:
>>
>>  Does anyone know how to construct a VCO or LFO with continuously 
>> variable/selectable waveforms like what is done on the MicroMoog ?
>
> I do (raises hand in back of class).
>
>
> OK, you use a center-tapped pot 50K or 100K linear. You put waveform A 
> into 1 leg, waveform B into the center-tap, and waveform C on the 
> other leg (all driven with *low impedances*. The wiper is the output, 
> a 1M to ground on it.
>
> Paul S.
>
The schematics can be found here: 
http://www.fantasyjackpalance.com/fjp/sound/synth/synthdata/07-moog-micromoog.html

Here's the specific page with the waveshaper:

http://www.fantasyjackpalance.com/fjp/sound/synth/synthdata/07-micromoog/150_dpi_gif/micromoog_multimoog_main_2.gif

The circuit is similar to what Paul describes.

-Dave