The sensor is generally composed of such three parts: A sensing element, a conversion element and a measuring circuit; And sometimes an auxiliary power source is also added.

There are three commonly used electronic sensors:

1. According to the physical quantity of the sensor, it is classified as displacement, force, speed, temperature, flow, gas composition and other sensors.

2. Based on the working principle of the sensor, which is classified as resistor, capacitor, inductor, voltage, Hall, photoelectric, grating, thermocouple and other sensors.

3. In the light of the nature of the sensor output signal, that is the switch type sensor whose output is the switch quantity ("1" and "0" or "on" and "off"); The output is an analog sensor; And the output is a digital sensor with a pulse or code.