Body Heat Powered Flashlight

Body heat powered flashlight using two tec1-12703 peltier tiles and CJMCU-3108 energy harvesting circuit board

Soldering Station, white led, 10-10K ohm resistor, two tec1-12703 peltier tiles

https://www.amazon.com/Bolsen-TEC1-12703-Thermoelectric-Cooler-Peltier/dp/B07G162T81?th=1

https://www.elecbee.com/en-25544-CJMCU-3108-LTC3108-1-Ultra-Low-Voltage-Boost-Converter-Power-Manager-Development-Board

https://www.digikey.com/en/products/detail/wurth-electronics-inc/74488540250/3672713

The CJMCU-3108 energy harvesting board does not come with the 100:1 transformer needed to make this circuit work and will need to be ordered seperately. There is a orentation dot on the board and transformer to locate it in the correct position when soldering

Solder the transormer to the board using a heat gun rework station, I managed to get it soldered in place with a regular soldering station. Solder the transformer breakout portion of the board to the main board at three points along the breakout seam.

The CJMCU-3108 board has 4 different V out settings dependant on jumping 4 pinout points on the board. 2.5v out not reccomended as most leds will need more than that to light. use the appropriate v out and resistor for the led or load you are using.

The side with the writing on the peltier tiles is the cool side and the blank side is the heat side. With the heat sides in direct contact with your hand and the cool side attached with thermal tape to a heat sink that stays ambient room temperature the circuit will turn on the led, however if the ambient temperature is too close or warmer than your hand, it will not work.