A very simple electronic thermometer can be designed using electronic diagram below. Thermometer displays temperature radiator not only on two displays, but also provides an output for switching can be used to connect a fan.
This circuit consists of four parts: a reference voltage source IC1, IC4 sensor, IC2 and IC3 the display, the switching IC5.
This temperature indicator indicates the temperature of a heat sink in high power circuits .
In this temperature indicator, diode voltage drop in ambient temperature is used as reference level. Temperature is measured by a transistor mounted on a radiator or near power transistor controlled.