DC fan speed can be controlled in order to optimize cooling, reduce noise
and decrease system power draw. There are various methods of controlling
fan speed. (Please place the mouse cursor over each item
to show a diagram)
Temperature Detecting Variable
2-speed DC Fan Motor
Customized two speed fans are available from Minebea. The high and low
speed may be specified by the customer. The low end operating speed is
fixed in order to reduce noise and lower power consumption.
External connection of 2-speed DC fan motor (Example)
Control by relay contact
Control by transistor
Switch-over of fan speed S.W. OFF :
LOW SPEED , ,ON : HI SPEED
Temperature detecting variable speed DC fan
The RPM is automatically controlled and synchronized with temperature variation
by installing a thermistor.
Connection diagram (Example)
Speed variation is enabled by varying the control voltage (0 to 6V) between
the Signal wire and ground.
PWM Control DC fan
In PWM speed control, a fixed frequency square wave is applied to the speed
control leadwire of the fan. The ratio of on time vs off time (duty cycle),
is directly proportional to the speed of the fan.
Correct Signal Connection:
Correct signal connection is important to prevent damage to the internal
fan IC. Connection should be designed as shown below: