[sdiy] RE: [AH] A question about voltage controlled oscillators.

[tomg@efm]

Here is my "new" favorite beginner VCO. You'll like it a lot because
there is a saw output and it's 1V/oct (unlike the 4558 vco on both counts).
It's 1 chip 3 transistors and a few odds and ends. The DIY layout has been
tested at this point and it works....
http://groups.yahoo.com/group/EFM_Synth/files/cookbook/3046_vco.pdf

I actually got a vco much like the 4558 version to scale. It was based on
the sonic6 oscillators and was very much a nightmare.
Good luck
Tom




>
> > Is it possible to build very simple (one or two opamps, a few
> > resistors,
> > a few capacitors, diode, transistor...) VCOs that will output up to
> > audible frequency, or... not?
>
> check this datasheet out:
> http://www.fairchildsemi.com/ds/RC/RC4558.pdf
> (oscillator's on page 8)
>
> but i'm having problems getting this to work.  i think part of it is that
> i'm probably mixing up my Vs' and Vc's.  can anybody shed some light here?
> i was powering this using a 9v on a clip, and i had + from the battery
going
> to both pin 8 and pin 5, - from the battery going to pin 4, and then Vc
and
> the outputs going to jacks, with the jack grounds tied together.
>
> can anyone see where i went wrong?
>
> thanks,
> alex