[time-nuts] Hobbyist grade or homebrew temperature testing chamber?

Bob Darlington rdarlington at gmail.com
Mon Sep 5 23:24:31 EDT 2016


Rick,

I'm going from memory here.  My former business partner (now deceased) had
a "beer fridge" setup as an environmental chamber for our instruments.  The
trick for stability was to run the AC compressor all the time, and push
against it with heat lamps.  The lamps were controlled with an Omega PID
controller with an RTD hanging in the fridge.   Model was RTD-805 (I just
happen to have it here in my office).  It has a little metal bird cage
around the sensor.  I believe he had a small fan in there too, to circulate
the air.  I removed the electronics and have since sold the commercial
refrigerator.

The instrument he was using in the chamber was an SRS 830 lock in
amplifier.

This is where my memory gets fuzzy.  SRS comped him another 830 because he
taught them how to get 10x or 100x the performance out of it.  I wasn't
working with him at the time but heard the story 50x over the years about
how impressed the SRS folks were about what he did.  I wish I knew those
details.

A buddy of mine that is now at Life Sciences contacted me about how we did
this.  He had the fridge and heater, but was heating using a thermostat to
controller the refrigeration compressor as well as the heater.  This did
not work.

And forgive me if this is way too course for time nuttery.  Just trying to
thow my 2 cents in and worst case you guys will school me on methods that
work even better.   Now I'm using a Sun environmental chamber which is
significantly smaller and meets my needs.

-Bob


On Mon, Sep 5, 2016 at 8:48 PM, Richard (Rick) Karlquist <
richard at karlquist.com> wrote:

> As we all know, step #1 in making a clock is NOT
> to build a thermometer :-)
>
> I thought I would check the brain trust here to see
> if anyone has seen a hobbyist grade temperature
> testing chamber or kit or homebrew design.  I
> have some crystals, oscillators, and other
> electronics I would like to characterize over
> temperature.  I know this reflector has discussed
> homebrew stabilization ovens; however, they
> have tended to have very long time constants
> (which makes sense for that application).  I
> need to be able to change temperature in a
> reasonable amount of time, and I don't need
> extreme stability.  Looking for any ideas,
> maybe in the "maker" spirit.  I think the
> size I need would be perhaps 1/2 the size
> of a shoebox.
>
> BTW, in case someone has a chamber to sell,
> let me know...
>
> Rick Karlquist N6RK
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