| 摘要 |
PURPOSE:To make and break an SCR by a stable period, by dividing main voltage by resistances which have been connected among anode-gate-cathode of an SCR, applying it to the gate, and making and breaking a switch which has been connected between the gate and the cathode, by a heat sensible element which has been coupled to a separate resistance circuit. CONSTITUTION:At first, a thermistor 12 is cool, a transistor 10 is turned on through a resistance 11, an SCR7 is off, and a half-wave current flows into an electric lamp 2 through a diode 6. A temperature of the element 12 rises, and when the transistor 10 is turned off at least, a trigger current flows into a gate G of the SCR7 through a resistance 8, it is turned on, and a full-wave current flows into the electric lamp 2. In this case, voltage between terminals 3, 4 drops, heating of the resistance 11 is reduced, the element 12 becomes cool, the SCR is turned off at last, and a half-wave current flows into the electric lamp once again. A thermistor 9 between the gate and the cathode of the SCR alleviates variations of the trigger current of the SCR, and a capacity 13 prevents an ignition error due to an external noise. According to such a constitution, the SCR is made and broken by a stable period. |
