[sdiy] XR2206 temeperature stability within +/- 5%

[Mike Beauchamp]

On 7/2/20 11:09 AM, Jean-Pierre Desrochers wrote:
> I need a pure sine wave generator adjustable from 10Hz to 60Hz  at around 5v
> peak.
> The adjusted frequency should stay stable within +/- 5% temperature wise.
> The project inside metal enclosure could have temp of up to around +40deg C.
> I have a bunch of XR2206 VCO IC on hand to use.
> I wonder if the best capacitor to be used here would be
> A polystyrene type for temperature stability.. (??)
> I'll use 1% metal film resistors for the rest of circuit..


Hi JPD, it's been a long time since I've used the XR2206, but it was 
stable enough for music even with an exponential converter for 1V/OCT 
tracking added to it.

For the Capacitor, I'd use a ceramic NP0/C0G and I'd check the datasheet 
on the resistors - some metal film resistors have different temperature 
coefficients.

The XR-2206 datasheet says "Excellent Temperature Stability, 20ppm/°C, 
Typ". So what's that, less than .1% change across a delta 40C?

I'm not really a math guy (math fatigue from University..), and if you 
have the IC's already, build one and try it. I've also set up small 
experiments heating and cooling circuits, using a laser thermometer to 
track and graph changes and that's easy to do if you also want to see 
how much things are changing.

Mike