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    Identification and detection of phototransistor pins


    Measuring Phototransistor Step 1: Prepare the multimeter before measurement, select the range switch to be placed in R × 1K block —— zero, remove the oxide layer of the phototransistor pin for use.The red pen is contacted with the emitter e of the phototransistor, and the black pen is contacted with the collector c. At this time, the hand of the meter should be deflected to the right to 10-30 kΩ, and the greater deflection of the hands indicates that the sensitivity is higher.Common silicon phototransistors are available in metal case packages, epoxy flat heads, and miniature.If the tube has only two legs, then the remaining foot is the collector c of the phototransistor; if the tube has three feet, then the closest to the e-foot is the base b, and the distance from the e-foot isIs the collector c.If there is a phototransistor that has already been used, the words on the shell cannot be identified, and it is impossible to know whether it is a phototransistor or a photodiode.

    How to distinguish this? Take a multimeter and dial to R×lk.Let the tube to be tested be a phototransistor (for example, 3Du23).At this time, the multimeter can be dialed to the R×100 Ω file. If the resistance value drops to several hundred ohms, the tube is a phototransistor, otherwise it is a photodiode.If the test results do not match the above, it may be that the test leads are wrong. You can exchange the test leads and test them again.In addition, do not use the multimeter’s R × lΩ, R × 10 Ω file to measure the phototransistor.Common phototransistors are 3DU0~7 type, 3DU11~51 type and silicon photoelectric triode assembly.Some silicon phototransistors have only two legs, which is due to the fact that the base b is not taken out during fabrication.


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