I would like to maintain temperatures anywhere from 80-150°F inside of an incubator (an augmented cooler).
Yogurt ferments at 110°F, Bacillus subtilis at 100°F, certain sprouts do well at certain temperatures, etc.
I can easily whip up the scripts to control a relay based on a temperature sensor.
What I need help with is picking the heating element scheme. I am interested in making nichrome coils, or cupronickel is also on my mind. I understand that what I need are VERY low temperatures, but does not that imply only that I need very low voltages? (yes i know, current is what dictates the heat produced by a resistor, but of course that depends on the supply voltage)
Would DC power be applicable? Can I use the power available from my microcontroller? Am I crazy?
Best Answer
You can just use a chassis mount power resistor or similar type as a heater. You will need to size the heater- typically one might figure out how much power is required to maintain the highest temperature you need, at the lowest ambient temperature expected, and then (say) double that power. Here is an example resistor from this surplus dealer (but you can buy them from a distributor in pretty much any value you need):
The voltage does not matter much, provided you have a supply available. Something like 12VDC would be safer for you to work with.
You might try a small incandescent light bulb of known wattage in the enclosure when it is complete to get an ideal of what power is required.