4046 VCO experiment

[Martin Czech]

You want a current input, right? Really ICO. The XR2206 has a reference
current input.  You can simply use this. I remember using the 2206 as
VCLFO ages ago.  I think I used a 3046 diff amp as exponential converter.
I think it was pretty nice when I tested a smaller cap so that the system
was running in the audio band. I did not check for higher frequency but
this should work since the 2206 is the usual integrator which is known
to be quite good in this respect.

The usuall application is a pot to gnd, which draws some current out of
the integrator. This is linear.

All from my head, better check the data sheet @ Harris.

I think there's also linearity information.

And finally: the Harris 3080 app note shows a 3080 tri integrator,
running up to 1MHz, sweeping several decades (screen shot).
It shows how to hf compensate etc. etc.
Wny don't you use this circuit? I guess there are a couple of 3080
arround. The advantage is that you can tweak this circuit to your special
needs, e.g. the C <=> CR hf compensation for the integrator (3040).
This will influence tri amplitude, but I think you are looking for a 
clock signal.

m.c.