[sdiy] Looking for low parts count HF-VCO

[René Schmitz]

Hi Daniel and all,

> I need a simple VCO with a range of about 500kHz to 1,5Mhz, I need it
> vary the samplerate of an ISD sampling/playback IC. 
> I vaguely remember somebody using a 4046 and have also read about using
> 555's for HF VCO. 
> The stability of the VCO isn't that important, it's a pretty lo-fi
> sound in the ISD IC's anyway.

Take a look at the three phase LFO. In the lower left corner you see a 
super simple VCO using one diode, one cmos schmitt trigger, a cap, a 
couple resistors, and a bunch of transistors. I think even the range 
does fit (with some extra decades towards the low end). And you have 
(more or less) exponential characteristic.

Cheers,
   René


-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159