[sdiy] adding sync to a vco/how does sync work

[harrybissell at wowway.com]

Sync causes the oscillator to reset from an external pulse.

Study some VCO that have sync to see how, Motohiko's VCO could have
a sync pulse injected into U1 pin 3 (make a narrow pulse with a
differentiator and jam the pulse into pin 3)

Hard sync makes the VCO reset at any time. Most VCO have hard sync
for dramatic filter sweep like sounds

Soft sync uses a weak reset pulse that will only cause a reset if the
VCO is near the normal reset point. This tends to allow oscillators to
maintain different pitches with phase locking (which a lot of people try to
avoid anyway...)

Triangle VCO's are much more complex to reset, in general. Sawtooth
cores are fairly easy

H^) harry



On Tue, 24 Jun 2008 13:29:09 +0000, Dan Snazelle wrote
> I have been finding some great uses for sync lately. i am wondering 
> how easy or hard it is to add sync to a schematic that does not call 
> for it. is it as easy as injecting a pulse wave into the timing cap?
> 
> for instance, the FARM VCO I doesnt have sync (i dont see it at 
> least) how hard would it be to stick it in somewhere?
> 
> http://www.aleph.co.jp/~takeda/radio/img/farmVCO-scheme.gif
> 
> is it possible to add it to a 555 oscillator? or a transistor 
> oscillator? i guess what i am asking is is it a pretty easy thing to 
> add to an oscillator circuit? thanks
> 
> also what is the difference between soft and hard sync
> 
> all help appreciated
> 
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> 
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Harry Bissell & Nora Abdullah 4eva