Vermes
Advanced Member level 4
It is a two-sensor temperature controller, that controls the central heating pump. This device turns off the pump on base of temperatures of two ponits. The solution can be used in water solar heating: if temperature in the heater is higher by the set tolerance than the temperature on the tank, then the pump is turned on. When the temperature drops, the pump turns off.
The controller is based on Attiny2313 and two Dallas termometers 18B20, because of their features (factory calibration, 1-wire connection and the possibility of connecting the sensor to a long cable). The 7-segment display is controlled directly by the microcontroller, relay 230/16A Coil 5V is enabled by transistor MOS. The following pictures show the used transistor in S-08 SMD housing.
The set temperature value is stored to the EEPROM so you do not loose it. Watchdog protects the whole system.
Link to original thread (useful attachment) – Dwuczujnikowy regulator temperatury