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Hi Brendan.
Cooling down the full 34 C takes about ~10 minutes and it stays there. Temp drops 10 degrees from ambient in ~20-30seconds. To zero in ~2 minutes and so on.
Major heat losses are from the copper heat sink mounting plate, despite insulation (replacing with 3mm acrylic) and the distance between the TEC and the sensor - this is insulated with double sided tape where possible, otherwise duct tape where space is restricted (which doesn't do much except keep condensation at bay).
I looked at several mods including cold boxes and decided that most of the energy is going into keeping the box and camera cold, instead of cooling the sensor. Even the cold finger mods waste energy with non-essential conductive couplings. So I figured that isolating the cold finger as much as possible should produce the best results and minimize losses through the camera body, draw tubes etc.
At the moment I have tested 3 times at max deltaT - no control, and once using PWM. I need to improve on the program for better stability. It held quite well at -5C (139, 0 - 1023), but not so well as I would like.
Typically, the accuracy of the TMP 36 is ~0.3C, but I am seeing steady temps with .01C tolerance, for long periods with the occasional + or - spike here and there. I think that's electronic noise as the thermal mass is fairly stable.
BTW. The camera is still working. Happy to provide details. It's a fiddly mod. The advantage is that all the camera controls are accessible and functioning, except for the Piezo sensor cleaning - manual only.
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