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Sep 26,2020

Variable capacitor detection method

A variable capacitor is a capacitor whose capacitance can be adjusted within a certain range. By changing the relative effective area between the pole pieces or the distance between the pieces, its capacitance will change accordingly. Usually used as a tuning capacitor in a radio receiving circuit.


Variable capacitors generally consist of two sets of pole pieces that are insulated from each other: a fixed set of pole pieces is called a fixed piece, and a movable set of pole pieces is called a moving piece. The moving plates of several variable capacitors can be assembled on the same shaft to form a coaxial variable capacitor.

How to detect variable capacitors?

Rotate the shaft gently with your hand, it should feel very smooth, and should not feel tight or even stuck sometimes. When pushing the load shaft forward, backward, up, down, left, right, etc., the shaft should not be loose.

Variable capacitor

Rotate the shaft with one hand and gently touch the outer edge of the film set with the other hand. You should not feel any looseness. The variable capacitor with poor contact between the rotating shaft and the moving plate cannot be used anymore.


Place the multimeter in the R×10k gear, connect the two test leads with one hand to the moving piece and the leading end of the fixed piece of the variable capacitor, and slowly rotate the shaft several times with the other hand. The pointers of the multimeter should be in place. The infinity position does not move.


In the process of rotating the shaft, if the pointer sometimes points to zero, it indicates that there is a short-circuited point between the moving piece and the fixed piece; if it encounters a certain angle, the multimeter reading is not infinity but a certain resistance value, indicating that the variable capacitor is moving There is a leakage phenomenon between the film and the stator.


The variable capacitor can freely adjust the capacitance within a certain range by changing the pitch of the pole pieces. The above is the method to detect variable capacitors, have you learned it? If you want to know more related product content information, you can view or purchase by visiting the SCIENTEK ELECTRICAL website.