understanding vcos-integrator and schimitt trigger?

loss1234

i think i MIGHT be finally starting to understand how a vco works (not just following a schematic) but i am not positive. can anyone point me in the direction of a super simple (no expo converter or waveshaper) integrator/Schmidt trigger vco?

all the vcos i encounter have too many parts to really intuit what is going on so i am hoping for something not too complicated (it doesnt have to sound good) Wink

thanks

Blue Hell · Posted: Sun May 25, 2008 7:07 pm Post subject:

Nothing to build there, but it explains stuff : http://sequence15.blogspot.com/2008/02/how-vco-works.html

shebb · Joined: May 07, 2008 Posts: 12 Location: usa

http://home.swipnet.se/cfmd/synths/friends/stopp/asm1lfo.pdf

that one is configured as an lfo because of the big capacitor, but I think its used as a triangle vco core, probably with an ota in place of R4, (and no P1) but thats just my guess. I don't actually know what actually drives most vcos.

I think the schmitt trigger is set up as a relaxation oscillator, but it uses a separate opamp integrator as the charging capacitor. if the relaxation osc and the integrator where separate, you would still get a triangle out, but its amplitude would decrease as the schmitt's frequency increases. so this setup somehow gets around this but I don't understand why.

that's all I know, maybe someone else will chime in with some concrete words.