| 摘要 |
A self-contained electronic digital thermometer is in the form of an elongated probe has a temperature transducing thermistor at a front end and an electronic digital display at a rear end. Circuitry housed within the probe converts the voltage across the thermistor to a digital signal for driving the display. The circuitry includes an operational amplifier fed by the thermistor voltage via a pair of selectable input resistors for providing different gains for the amplifier and fed by a voltage source via a different pair of selectable input resistors for providing different biases to the amplifier. The different gains and biases are selected by a switch for enabling readout in either degree Fahrenheit or degrees Centigrade. A differentiator and comparators are also provided to drive a series of lights indicative of whether the temperature is increasing, decreasing or stable.
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