| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive circuit for an automatic variable speed fan. SOLUTION: A fan drive circuit, a temperature control circuit and a current circuit are provided. The fan drive circuit controls two transistors sequentially so that the transistors are turned on and off. If alternately excites two drive coils. It turns the fan. The two transistors control two sets of coils of the fan and the coils are turned on and off. The thermostat of the temperature control circuit detects the temperature. Thereby, the magnitude of a current flowing by changing a resistance is controlled. The current is fed bad to the fan drive circuit via the current control circuit. The fan changes its rotational speed according to the magnitude of the current. Thereby, the operating speed of the fan is controlled automatically. |
