| 摘要 |
An apparatus for controlling a heating element for heating a substance in accordance with a maximum power which is to be applied to the heating element and in accordance with a selected temperature to which the substance is to be heated is used in combination with a temperature sensing probe for sensing the temperature of the substance heated by the heating element. The apparatus includes first circuitry for generating a first control signal which is a function of the difference between the selected temperature and the sensed temperature and second circuitry for generating a second control signal which is a function of the maximum power. The apparatus also includes a relay for providing power to the heating element and circuitry responsive to the first and second control signals for selectively applying power provided by the relay to the heating element whereby the amount of power applied to the heating element is reduced as the substance approaches the selected temperature thereby avoiding overheating the substance to a temperature significantly above the selected temperature.
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