Cpu Cooling Fan Circuit. A 10kω pot is connected between supply and pin 7 with wiper of the pot connected to pin 7. However in recent years the technology of using these fans has evolved significantly.
3 pin connectors are usually used for the smaller chassis fans with lower power consumption while 4 pin connectors are usually used by cpu fans with higher power consumption. The circuit is based on good old 555 timer ic. Interest has been growing in integrated circuits for controlling the speed of cooling fans in personal computers and other electronic equipment.
A 4 wire cpu motherboard fan is a standard brushless dc bldc fan but has four wires extending from the casing.
One for the positive or hot lead and one for the negative or ground. The third wire varies depending on the manufacturer but usually it is blue or yellow. Interest has been growing in integrated circuits for controlling the speed of cooling fans in personal computers and other electronic equipment. It is configured as an astable multivibrator.
