| 摘要 |
PURPOSE:To prevent at influence of a DC drift by containing a monostable multivibrator whose time constant is varied by a temperature variation, in a heat insulating part together with a heating part, and inputting an output of this monostable multivibrator to the heating circuit. CONSTITUTION:A monostable multivibrator 2 inputs a repeated pulse of an input terminal 1, and outputs an output pulse whose pulse width is varied by a variation of a temperature sensing element 5. A heating circuit 3 which has been contained in a heat insulating part 4 together with a containing circuit 6, the monostable multivibrator 2, and the temperature sensing element 5 inputs this output pulse, and controls a heating value. As for a circuit in the containing circuit 6, its temperature variation is suppressed to the utmost, and an influence of a DC drift is prevented, and also deterioration of an S/N caused by an unnecessary frequency can also be prevented.
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