[sdiy] AN299 VCO (was: SDIY list troubles)

[Tom Wiltshire]

On 29 Apr 2008, at 15:09, flight wrote:

> Last year I spent a few weeks playing around with this circuit. I  
> used a
> TL074, which worked fine. The VCO works nice except for its  
> horrible drift -
> I probably should have insulated the CA3046 from stray air currents. I
> abandoned the project finally, as I just couldn't get it to  
> stabilize. I ran
> it for up to 5 hours and it just wouldn't sit still! It also has a  
> lengthy
> warm-up period while the array heats up (5+ mins). Here's the  
> schematic I
> drew from the App Note: http://www.flightofharmony.com/stash/AN299  
> VCO.pdf .

I thought the whole point of this circuit was its clever temperature  
compensation. After all, that's a lot of transistor array to use for  
pure decoration. If it doesn't actually work, we might as well all go  
back to using tempcos.
Has anyone else had any experience with it to share?

Thanks,
Tom