| 摘要 |
PURPOSE:To keep the output electric current constant and stabilize the operation of a solenoid valve by operating a transistor as emitter grounding type amplifier and supplying the input voltage through a constant voltage maintaining circuit. CONSTITUTION:The emitter terminal TE of a transistor Q1 is connected with one edge of an electric power source BV through a resistor RE, and a collector terminal TC is connected with other edge of the electric power source BV through the solenoid coil of a solenoid valve SV. A constant voltage maintaining circuit CV is connected with the base terminal TB so that the input for the emitter grounding type amplifying circuit of the transistor Q1 is obtained. A resistor RB is connected between the base terminal TB of the transistor Q1, and other edge of an electric power source BV, and the base electric current of the transistor Q1 is controlled so as not to become excessively large.
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