Option One: "Mini Air Cooling Fan" is the use of PWM control PWM digital output of analog circuits for controlling an effective technique, especially in terms of motor speed control, can greatly save energy. However, a large initial investment.
Option Two: "Mini Air Cooling Fan" SCR control reality by controlling the triac conduction angle, so that the output voltage is changed, so that the input voltage applied to the fan is changed to adjust the "Mini Air Cooling Fan"speed to achieve variable speed wind each gear.
The design requirements from considering two practical options.