Then measure the resistance between the common terminal and the terminals at both ends of the capacitor with a multimeter. The terminal with a slightly larger resistance value is connected to the other end of the power supply, and it is absolutely connected to forward rotation at one time. If you want to change the direction, you can connect the power cord at one end of the capacitor to the other end. Non-polar capacitors, such as mica capacitors, polyester capacitors, ceramic capacitors, etc. , can be directly connected to the circuit regardless of polarity.
Capacitors with polarity, such as electrolytic capacitors, must be connected according to the polarity of the circuit, that is, the positive pole of the capacitor is connected to the positive pole of the circuit and the negative pole of the capacitor is connected to the negative pole of the circuit.