Electronics Exponential VCO circuits.

Hi,

I'm trying to throw together a circuit for a VCO that will produce an output frequency range from about 10kHz to 1 MHz - with the circuitry controlling the voltage input running from +/- 15V supply rails - so clearly it is going to need to be exponential.

I've done a bit of Google bashing, and found that alot of these sort of things are not uncommon for analog synthesisers and such forth, and the use of OTA's such as the LM13700 to implement them is possible.

Now, what i can't find is a rough schematic to work off - does anyone know where i might be able to find one?

Cheers.

 

Which waveform would you like?

 

Square wave.

Thanks.

 

Any ideas?

So you can't do it with a square wave output? A triangle waveform should be fine - then a simple comparator could be used to square it.

Thanks!