Most VCO’s have a PWM function on the square wave audio output, but it is possible with some use of comparators, and by using Level Adjustment modules as “audio gates” we can achieve a similar function on sine, saw, ramp and triangle waves. The example prefab is here
Keeping the PW input under control.
Due to the way the gating works, we need to keep the range of the CV input under control. Rather than leaving things so that each CV you might use to control the prefab would have to be range limited I have done this in the prefab itself. We just need to limit the output range really, this needs to be from +5 volts, to +9.9 V.
Going outside this range won’t cause the prefab to crash, or do anything bad to the VST, it just won’t work as expected. However I have limited the input range from 0 to 10 V. Negative CV’s won’t work at all.
Setting the width of the output waveform.
This is done by controlling the point at which the Level Adjusters used as audio gates switch on, and whether they turn on on the positive or negative cycles of the input waveform.
Here I’m feeding in a +/- 5V peak to peak sine wave from an Oscillator, and the PW input as at 0 volts, by using the Scope3 we can see what’s going on.
By the time we get to 5 V on the PW input you can see how the gate pulses have changed, and with that, the output is no longer a sine wave. It’s not clipped but the shape has changed.
And at 9 V on the PW input the change is quite drastic.
And the effect of the prefab on a Sawtooth-
This module will work on all waveshapes except a square wave (Square wave is just an on/off signal, so changing the module doesn’t work at all on a square wave).
Feeding noise through the modulator will give an output ranging from full noise, to more of “static” type noise.
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