Schematic Volt

DC fan control circuit for power amplifier .Variable speed DC fanThis series of works based on the input signal. Speed ​​/ fan rotation depending on size of the input signal coming from speaker lines. If there is no signal then the fan will spin slowly according to the setting VR1.Input supply can be taken directly from the main transformer power amplifier, 12V CT 12V, so no need to increase the transformer again.

Circuit Schematic Electronics | CSE

This circuit has been tested and do not cause buzzing.correction: the lowest R: 560 ohm