[sdiy] square to sine

[David G Dixon]

> What a welcome! Highly appreciated, Neil :) Don't worry, I 
> won't stop thinking about synth diy even if I live out of a 
> paper bag ;)
> 
> Dave, I'm going out on a limb here, but this reminds me of a 
> technique normally used for asynchronous sample rate 
> conversion, which is "flywheel sync". Basically, you have a 
> model of a flywheel - with torque and friction - and each 
> rotation of it is one output wave cycle. As clocks come in, 
> you give the flywheel a "push" or "jolt". If the jolts stop 
> coming in, the flywheel stops eventually. If they come in at 
> a lower frequency, the flywheel spins slower. If you rapidly 
> lower the frequency, you can add some friction (for example, 
> friction gets -df/dt added to it). It is normally used to 
> prevent jitter, but can also be used for syncing two 
> different waveforms together.

That sounds like Ian Fritz's "Kick" synchronization scheme.  Ian?