| 摘要 |
A thermal control variable speed fan motor comprises a rectifying circuit, a differential amplifier, and a temperature-sensing circuit. The rectifying circuit converts a speed signal detected from the fan into a voltage that is outputted to a negative terminal of the differential amplifier. A positive terminal of the differential amplifier is connected to the temperature-sensing circuit that is connected in series with a power source. The temperature-sensing circuit includes a temperature sensor having a resistance that varies in response to a change in ambient temperature. When ambient temperature rises, the drive voltage outputted by the differential amplifier increases and the fan speed increases. When ambient temperature reduces, the drive voltage decreases and the fan speed decreases, thereby changing the fan speed linearly by thermal control.
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