| 摘要 |
PURPOSE:To reduce the leakage current at turning-off of switch, by supplying a voltage which is made to a constant voltage with thyristors flowing a current less than a latching current, to a sensor circuit. CONSTITUTION:When a transistor (TR)Q1 of a sensor circuit 1 is turned on, a thyristor SCR1 is turned off, and a SCR2 is turned on by the anode voltage of the thyristor SCR2 to be increased. A voltage fed to the sensor circuit 1 is the sum of a Zener voltage of a Zener diode D2 and a voltage between the gate and the cathode of the SCR2, which is a constant voltage. Further, a current which is only less than the latching current flows to the SCR2. When the TRQ1 turns off, the SCR1 turns on and the SCR2 remains turned off. A voltage which is made constant by a diode D1 is fed to the sensor circuit 1 via a diode D3. |
