uh.. am I an idiot?

[Harry Bissell]

Most thermistors don't have a very linear slope of temperature... some
are better than others... The Temperature Compensating Resistors
(commonly) used are wirewound and designed for a 3300ppm tempco... they
are very linear over a wide temperature range...

The Tempco resistors only compensate for the expo converter
transistors... not the whole VCO.  Measuring the performance of the
tempco circuits is tough also... rule of thumb is to keep the
transistors and tempco resistor in thermal contact, away form air drafts
and maybe potted in epoxy so that any temperature change has to happen
slowly (thermal mass).

The neatest idea for testing I've heard lately (on list) was to use an
electric heating pad in a cardboard box. Thanks (whoever said this...).
I'll have to try it soon.

Since the tempco thing has been an ongoing problem since the first days
of synths... I don't think this (alone) would qualify you as "idiot". So
sorry  :^) Harry

andersdl at plattsburgh.edu wrote:

> Hi -
>
> So I'm looking at this sample pack from Thermodisc and notice
> that one of the NTCs in it lists temp co as an application.
> Which gets me thinking that maybe Mouser and Digikey sell
> thermistors. So I check their online catalogs and lo -- they do
> sell them.
>
> Mouser even lists the temperature value of most of their
> thermistors (3800 is most common, iirc). Anyway, I'm looking at
> TomG's MadMouse... he recommends 1K tempcos. Are they NTCs or
> PTCs he's referring to and can I use thermistors from Mouser?
>
> Or am I totally crazy here?
>
> David Anderson
> Web Site Admin
> Plattsburgh State University
> 518-564-4433