[sdiy] Cheap and cheerful single rail VCO recommendations?

[Julian Bunn]

Hi,

I've just rejoined the list after a few years away.

I'm currently building a simple modular analogue synth. The first
module, a 10 step sequencer with Nixie tube readout(!), internal
and external clock inputs is complete and functional.

Now I need a VCO to test it with. I'm looking for something simple,
preferably with a several octave range, 1V/octave, using a single
0-9V supply. A single ramp output is fine.

Looking around, I found a few designs based on CMOS inverters, which
looked promising, but I don't seem to be able to get any of them to
work (probably my rusty breadboard skills)! Others based on e.g. a
unijunction transistor are a little too crude.

The VCO I'm familiar with is the one I built for the Minisonic, which
would fit the bill (apart from the need for a 12/6/0 dual supply!), but
I found it ticklish to set up (the ccg generator based on dual transistors
was finicky).

I'd welcome some pointers ... thanks!

Julian