| 摘要 |
A kiln temperature controller is provided comprising a circuit for providing a first signal representative of a selectable kiln temperature and a temperature detection circuit for providing a second signal representative of the detected kiln temperature. The temperature detection circuit comprises first and second thermocouples disposed in the kiln and in the temperature controller, respectively. The first and second thermocouples are coupled in series and in opposite polarity. A solid state temperature sensing circuit is provided in the kiln temperature controller, the temperature sensing circuit being coupled in series with the first and second thermocouples and providing an output signal having a polarity opposite that of the second thermocouple to nullify ambient temperature variations of the kiln temperature controller. The second thermocouple is provided with an isothermal relationship with respect to the solid state temperature sensing circuit and a solid state temperature compensated voltage source is provided for the temperature sensing circuit, the compensated voltage source being provided with an isothermal relationship with the temperature sensing circuit and the compensated voltage source being provided with Vbe characteristics identical to the Vbe characteristics of the solid state temperature sensing circuit. A comparator coupled to outputs of the temperature detection circuit and the signal representative of a selected kiln temperature is employed to actuate the kiln and apply heat to the kiln when the detected kiln temperature is below the desired kiln temperature.
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