Temperature controller relay for a freezer with broken thermostat.
It keeps AC power on while the temperature is above TEMP_MAX (-17°C) and turns it off when the temperature goes below TEMP_MIN (-20°C). I used the ° sign of the LED display as "power on" indicator.
- Arduino Pro Mini clone
- Dallas DS18B20 1-wire thermometer.
- Cheap USB charger as AC/DC power supply
- TM1637-based 4-digit 7-segment LED display
- 5VDC control / 240VAC switching relay
This is how the DC parts are connected. The power supply goes on the lower +/- leads, and the AC bits obviously connect to the relay.
