AW: VCO temp compensation ideas

[The Dark force of dance]

Y-ellow Y'all.
I sent this this a few days ago but it didn't crop up on the list. Therfore,
for what it's worth, I'm sending it again. It's a bit late now but at least
I responded.

Be absolutely ICebox.

Y-ellow Juergen 'n' all
At 11:20 AM 10/24/97 +0200, Haible Juergen wrote:

>	It will help if you give us a circuit with a commonly available
>thermistor,
>	and the right resistor values to trimm it down, and even better,
>if you
>	can tell us about the linearity of the circuit.
>
>	I'd love to see this circuit !

I'm just wondering why people aren't using them. I'm not sure if I have a
circuit off hand. Hold on. Maybe. Nope Sorry I just got side tracked reading
the specifications for the Synthi-100. Nice little box. Incidently it's
curious to note that they've done something similar on that to what everyone
was talking about doing with the VCS-3's patch bay. IE: it's all coupled
with potentiometers. But that's another story.

Anyway I'm sure that using thermistors use to be the common way of
stabilizing VCOs. I can't remember exactly but you pick a positive or
negative temperature coefficient depending on your drift problem and you
trim it out so that it's effect on the circuit matches it's drift.
Presumably you could probably even whack it across the control voltage and
adjust that up or down to suit.

But I've got to admit I'm not a big fan of VCOs because of the
temperature/drift problem. I use to own a VCS-3. :-( I haven't built a VCO
in years and the last one I did build used a transistor in thermal contact
but it wasn't entirely successful as I recall. Anyway If I dig one up you'll
see it here first.

But the bottom line is that I'm just wondering why more people aren't at
least exploring that option.

Be absolutely ICebox.