The traditional thermostat "Tiny Cooling Fan" is the use of a fan bearing temperature probes to detect nearby fan inlet temperature, and thus the fan speed can be adjusted. This thermostat solves some problems, but there is rough precision, and temperature control "Tiny Cooling Fan" can do high-speed low rotational speed of the transmission poles. PWM pulse width modulation circuit is referred to, in the industrial control, micro controller already widely used. And he and motherboards Intel CPU temperature detection combined, applied to the radiator "Tiny Cooling Fan" precise control of speed, and achieved good results.