| 摘要 |
A speed control system is provided for controlling temperature within a chassis. The chassis includes therein a temperature sensing device for producing a temperature signal representative of temperature within the chassis, a fan, and a fan speed controller. The fan speed controller produces a nominal fan speed control signal comprising a train of pulses, successive pulses having a duty cycle related to the temperature signal produced by the temperature sensing device, such time durations decreasing with increasing temperature. The speed control system includes a decoupling circuit responsive to the nominal fan speed control signal for, in response to relatively a low duty cycle, coupling the nominal fan control signal to an output of the decoupling circuit, and, in response a relatively high duty cycle, producing a preset fan speed signal at the output of the decoupling circuit. The fan has a speed in accordance with the signal at the output of the decoupling circuit.
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