A compact yet professional thermostat / thermometer offering a digital display that shows the current temperature in either Fahrenheit or Celsius, and allows you to digitally set a target temperature to be maintained. There are two modes of operation: cooling or heating. In cooling mode, the thermostat activates the relay when the temperature goes above the preset target temperature and deactivates the relay when the temperature falls below the target. Conversely, in heating mode, the thermostat activates the relay when the temperature falls below the preset target and will deactivate it once the target temperature has been reached. The circuit is designed around a Microchip PIC in conjunction with a Dallas/Maxim DS18B20 temperature sensor. An adjustable hysteresis setting is also incorporated to prevent wear on your heating/cooling device. All settings, including the current target temperature, are stored in non‐volatile EEPROM memory and will not be lost in the event of power failure. The relay can handle loads up to 10A @ 110VAC or 24VDC (5A @ 220V AC).