Chinese Trimmer potentiometer is a resistor element with three lead-out terminals whose resistance value can be adjusted according to certain changing rules. Potentiometer is usually composed of resistor and movable brush. When the brush moves along the resistor, the resistance or voltage which is related to the displacement is obtained at the output end.           

Chinese Trimmer potentiometer can be used as either a three-terminal element or a two-terminal element. The latter can be regarded as a variable resistor, because its function in the circuit is to obtain the output voltage which is related to the input voltage (the applied voltage), so it is called potentiometer.