[sdiy] XR2206 VCO -- worth it ?

[David G. Dixon]

> I'm pondering whether to get a bunch of XR2206 before they go
> away. Thomas Henry managed to get 1 cent linearity from 60 Hz to
> 7.7 kHz :
> 
>   http://birthofasynth.com/Thomas_Henry/Pages/XR-VCO.html
> 
> A single-chip VCO would be nice for a poly synth. But the part
> count isn't that different from the usual saw core design. You
> still need a polystyrene cap, a matched pair and a tempco
> resistor.
> 
> Feature-wise, you gain an unusual triangle-sawtooth hybrid but
> you lose PWM and the separate outputs.
> 
> On balance, I get the feel that it's just not worth it. Am I
> missing something ?

Hey Andre,

I bought an XR2206 ($8!) once upon a time to build this thing, but then I
got obsessed with 2164-based things, and lost the motivation.  I can't say
I've missed not having it.

If you're looking for low parts count, and want to avoid fancy expo parts,
then stay tuned for my 2164 Expo Tricore.  I'm pretty certain it won't
achieve 1 cent linearity over the musical range, but it should be within 2
cents.  Plus, it's very easy to adapt it to TZFM.  No matched pair, no
tempco, and (believe it or not) a tiny little C0G ceramic cap works
perfectly in VCOs.