Simple DC Fan Controllers - Schematic Circuit schematiccircuit›Electronic HobbyThe series of Simple DC Fan Controllers. DC fan controller circuit above uses 2 trimpot which serves to set the maximum speed of a DC motor (P2) and to regulate the temperature at the lowest speed DC motors up (P1). P1 on the circuit a DC fan controller functions to determine the reference voltage op-amp TL082 comparator, voltage reference is used as the reference temperature sensor is a DC motor. PC Fan Controller Circuit - Electroschematics Schematic of the PC Fan Controller Circuit. Place the temperature sensor in the warm air of the fan. When the PC is connected the speed rotation of the fan will be pretty high because of C1 but will decrease at a minimum value. Measure with a thermometer the air temperature close to the sensor.