Is it possible to test whether the optocoupler is good or bad with only one multimeter?
Application in logic circuits Optocouplers can form various logic circuits. Since the anti-interference performance and isolation performance of optocouplers are better than those of transistors, the logic circuits formed by them are more reliable. Used as a solid switch In the switching circuit, it is often required to have a good electrical isolation between the control circuit and the switch, which is difficult for general electronic switches, but it is easy to achieve with a photocoupler.
Application in trigger circuit Using optocoupler for bistable output circuit, since light-emitting diodes can be connected in series to two emitter loops, it can effectively solve the problem of isolation between output and load. Application in Pulse Amplifying Circuits Photocouplers are used in digital circuits to amplify pulse signals.
Application in linear circuits Linear optocouplers are used in linear circuits, with high linearity and excellent electrical isolation performance. Applications in special occasions Photocouplers can also be used in high-voltage control, replacing transformers, contact relays, and A/D circuits and other occasions.
After reading the above content, you know that the optocoupler plays a very important role in the circuit. If the optocoupler is damaged, the circuit cannot be guaranteed. Today we will talk about how to test the quality of the optocoupler. It can test whether the optocoupler is good or bad.
The input terminal of the photocoupler is a light-emitting diode, so you can use the diode file of the multimeter to judge whether the light-emitting diode is damaged. It is the same as the method of measuring the diode. If the conduction voltage drop can be measured (the reverse cut-off state can also be measured) , then basically it can be judged that the input end is good, but what about the output end is still uncertain.
Since the output terminal will only be turned on when it receives the optical signal from the input terminal, the output terminal is in the cut-off state when the input terminal is not powered on, so it is impossible to judge whether it is normal by directly measuring the output terminal. You can use the following scheme, connect a resistor in series to the input terminal and connect the power supply, use a multimeter to measure the conduction voltage drop between pin 4 and pin 3, which is close to 0 under normal circumstances.
Since the input terminal needs to be powered on when judging whether the output terminal is normal, it is impossible to determine whether the photocoupler is normal with only a multimeter.
