Design a ttemperature control system utilizing a relay again to turn a heater on and off. When the relay input voltage is close to +12V the heater will turn on and if the input is close to OV the heater will turn off. Use this heater to maintain the temperature roughly between 20 to 22 degrees Celsius. Indicatee the temperature of the house when within 21 + 1 degree Celsius, by turning on an LED or a light. Transistors (with their temperature dependency) are usually used as a temperature sensor. Alternatively, You can consider a thermistor as your temperature sensor.