How to detect photoelectric switch sensor

Commonly used photoelectric switches have four lead pins, two of which are infrared emitting diode pins, and two are phototransistors for light receiving.

First find out the two pins for infrared emission: because the four pins can clearly identify a group of two adjacent leads, and you can use a multimeter Rx1k resistor, when the photoelectric switch is not affected by light, use positive, For the measurement method of negative resistance, you can easily find that only positive and negative resistance can lead to one group, and the lead resistance of the other group is large. In this way, it can be determined that the two leads of the forward resistance and the reverse resistance are the leads of the infrared light emitting diode. In the positive resistance, the black pen is connected to the anode of the infrared emitting tube. When the two wires on the photoelectric switch are large, one set is the wires of the phototransistor C and E. In the multimeter, the red pen of the Rx1k is connected to a wire, and the black pen is connected to a wire. Then let the photoelectric switch see the light and watch When the size of the hand is reached, swing to the right; then the red and black dial switches, and then let the photoelectric switch see the light, write the scale of the dial on the right swing, test twice, with or without light, the multimeter pointer deflection amplitude is large The black pen is connected to the collector of the phototransistor C, and the remaining wire is the E pole of the phototransistor. It is good if you can follow the rules of photoelectric switch above. What does not meet the above rules is a bad photoelectric switch.