| 摘要 |
PURPOSE:To prevent the circuit from erroneous operation in response to noises from the outside and surges etc. by a method wherein a phototransistor or relay for prevention of erroneous working is inserted between the emittor of a photo-oscillation element and the gate of an auxiliary thyristor. CONSTITUTION:When an input signal is received, the phototransistor 11 is in ON condition, and a transistor 14 is put in OFF condition. When a source voltage drops under Zener voltage and a photo-oscillation element 6 turn on, the currents flow into the gate of the auxiliary thyristor 5 through a resistor 13 to turn the switching circuit on. When no input signal is received, the phototransistor 11 is put in OFF condition. At this time, even if the photo-oscillation element 6 makes an errneous works caused by the outside noises and serges, part of the currents flowing into the gate turns transistor 14 on passing thru a transistor 15 and the transistor 14 absorbs most of currents flow into the photo-oscillation element 6, so that no current flows into the gate of auxiliary thyristor 5 nor the switching circuit is erroneously operated. |
