Do you remember that I have asked you such a project a week or so ago, to do FM modulation aka adding vibrato to the oscillator bits ?
Of course, you can modulate the VCO at the input, but there is no way to keep tune tracking correctly and to modulate the signal.
By now, I found two ways to work it out, using the arduino or to modulate the VCO, or to make yourself a bit module, which can combine the modulation wave and the tune input.
For such, we certainly need a sone wave. The arduino can generate a sine PWM or we can use brute LFO.
More of this will certainly follow shortly in this forum, and we can compare the circuits all together and make combinations 😜
BTW, did you check out the string synthesiser that I've made possible into the littlebits environment ?
And oh, @alexpikkert, how did you manage to tighten the spin disc on the fan ?