What is an optical coupler and how to measure it?

Last Update Time: 2018-12-15 14:23:34

1.Optical coupler also known as photoelectric isolator, referred to as optocoupler.

Optical couplers use light as a medium to propagate the Telecom number. The light emitting diode and the photosensitive transistor inside the optocoupler only convert the voltage or current change of the front and rear stages into light changes, and there is no electrical connection between them, therefore, it can effectively cut off the potential connection between circuits and achieve reliable isolation between circuits. The pin of the light source is the input terminal, and the pin of the light receiving device is the output terminal. The light intensity of the optical coupler is determined by the magnitude of the excitation current, and the light intensity is applied to the light receiving device which is packaged together, because of the photoelectric effect, the photoelectric current is generated, which is led out by the output end of the light receiving device, so that the conversion of the electric light and electricity is realized.

There are many kinds of optical couplers. The common light source is the light emitting diode, and the light receiver is the photodiode, photosensitive transistor, etc.

 

2.Measure the optocoupler

Because the way of the optical coupler is not the same, so the test should be based on different structures for measurement and judgment. For example, for the transistor structure optical coupler, the test transistor should be checked according to the method of test transistor.

 

( 1 ) The input and output judgment is due to the input of the light-emitting diode, and the output end is other components. So with RX 1K block, measuring the forward resistance of a pair of feet is hundreds of Europe, the reverse resistance in the tens of thousands of Europe, then the measured pin is the input terminal. The other pin is the output end.

 

( 2 ) Good or bad judgment

Use a multimeter to judge good or bad. The RX1KQ is used to measure the resistance of the input pin, the forward resistance is several hundred ohms, and the reverse resistance is tens of thousands of euros. Then use the multimeter RX10kQ block, in order to measure the input terminal ( launch tube ) of the two pins and the output terminal ( receiver tube ) between the pins of the resistance value should be infinite, there should be no leakage resistance between the transmitting tube and the receiving tube.


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