[sdiy] Soft sync?

[jlippard]

Hi everyone!

I have a question about soft-sync, which I really don't know too much about. 
As I understand, it's achieved when the frequencies of one waveform are close 
to the frequency of another waveform (or its harmonics) and they lock 
in-phase. (If I've got this wrong, stop me here.) ;)

My question is, how is this usually achieved when you deliberately want it to 
happen, a la hard sync?  I was looking at the schematic for PAIA's 9720 VCO, 
and as far as I can tell it is achieved by using the the waveform of the 
sync-ing oscillator to modulate the thresholds of the Schmitt trigger in the 
sawtooth reset circuit.  Is this typically how it's done?  (If I've got this 
wrong, *please* correct me!)

Cheers,
Jonathan