How about it? Experiments of the third kind , take 999999. Update Fridge test 100% a success!
Today I did the low temperature test. The design was to keep the hotplate stable to -5C environment. A first test in the fridge at 10°C made no difference.. So I decided to put it into the freeze box of the fridge,
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How many stars means how many degrees below zero?
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I dunno, but the little the car thermometer showed about -15°C
Left it for some hours, to adapt to that temperature, again nothing happened...
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The numbers are from left to right: External reference voltage (for check), temperature sensor voltage - setpoint is 490 for 40°C here, 1 count is about 1/2 or 1/3 degree C -, first light channel, second light channel (the dark side is not blacked out yet), and the heater PWM. Normal PWM is about 54 at room temperature, now it went up to and oscillates around about 150, The maximum PWM is 255... So it seems we are even good for -20°C or lower.. As this is to run indoors we can only hope that never really happens, but climate chance freaks may expect that within the one year measuring period perhaps ;-) Oops, should not have touched that subject., You can see the 1 ADC step noise for the light sensors, this are 1 second samples, data points are averaged over 3600 samples (one hour).
So next should be the oven test:
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But in fact it already had the full sunshine hot test...
This is the power it was drawing at -15°C:
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That would empty the batteries fast if a mains failure happened, 350mA, still good for 4 hours on new alkalines I think.
FYI the pizza is mushrooms and cheese, and the ice cream Straciatella. Not sure that influences the results a lot.