Miniwave Highpass modulation
An implementation of the Bob Borries modulation trick to mimic PWM on a Miniwave.
Simply put, an LFO (or EG, or other modulation source) sweeps the cutoff on a ramp (rising sawtooth) wave being fed into a highpass filter. The output of the highpass HPF drives the Miniwave input.
Changing the waveshape of the ramp changes the spectral content of the Miniwave, lending a PWM style tonal sweep.
Not everything sounds great, but they beauty of it is that one can go from subtle sweeps to nails-on-a-chalkboard grind with relatively little effort.