Nevada Space Grant
We use two kinds of heaters, electric and chemical
We use HotHands hand and body warmers for our larger payload boxes. They provide 130°F Heat source. They don't work well at high altitude but you can get a little bit of heat for your electronics so they don't get too cold. You can find these at Wal-Mart or a sporting goods store.
for the little payload boxes we make electrical heaters.
Our heater is made from 1 to 3, 5.1 Ohm 5W resistors, we place these on a circuit board
Cut the board to fit the resistors
Put the leads of the resistor through the board and solder two leads on one end together.
You'll need one 9V battery for each resistor.
Take 1 9V battery snap for each 9V
Solder the red leads together
Solder the black leads together
Solder the black leads to a switch
Solder a black wire to the other switch terminal
Take the remaining two resistor leads and solder one to the black wire from the switch and the other lead to the red 9V lead
Take wire mesh and cut out a section to fit over and around your resistors
Attach it in place however you want.
Flip the switch and make sure the resistors heat up, it's also a good idea to test the voltage of the circuit to make sure the batteries are giving enough juice (~9.5V). The batteries will drop in voltage to about 7.5V in the first half minute. If it goes down too much lower your batteries won't last very long