XR2207 and XR2209 VCO chips

[Martin Czech]

> have them anymore.  The XR2206 is still popular and probably better than
> the other two anyway.
> 
> Secondly, they have linear frequency sweeps.  So 1V/oct. operation is out
> (this is considered the biggest stumbling block).  
> 

partly true. I remember building an expo controlled LFO with XR2206.
It is current controlled, so you can use a normal expo converter.

The XR2206 has a sine wave output with the lowest distortion (compared to
MAX083 or Harris chips). OTOH you can't have tri and sin at the same time.

I don't think I would use it today, a discrete matched sine converter
can yield much better results, and a tri oscillator can also be made
discrete with very good results (look at CA3080 app. notes).

m.c.