[time-nuts] Hobbyist grade or homebrew temperature testing chamber?
namichie at gmail.com
Tue Sep 6 01:55:32 EDT 2016
Constant temperature chambers are not hard to build.
I assume you want stability in the range 0.001 to 0.01 degC.
I have made a few of these chambers, about 1 cubic feet, out of 3/4 inch particle board,
it is not a brilliant insulator, but you want some heat loss.
Make a partition at one end with both ends open as a radiation wall.
Behind the radiation wall instal one or two tungsten filament lamps,
about 50 watts for heaters, these have low thermal mass and fast response.
Instal a computer sized fan, behind the wall to reduce any radiant output to circulate the air in the box.
You want a small hurricane. On the far side of the box from the partition place a small bead thermistor,
glass encapsulated are good. In the air flow this should have a response time of a second.
A proportional controller sets the temperature. Air velocity of up to 1m/s will not disturb items being tested
but ensures low temperature gradients.
The trick is to have fast response in heater and measurement and no hysteresis in the controller.
> On 6 Sep 2016, at 12:48 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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