| 摘要 |
PURPOSE:To stabilize the working at a low temperature for a circuit which applies a temperature dependence resistor to a phase controller, by controlling the phase angle with said resistor at normal temperature and with a Zener diode at a low temperature respectively. CONSTITUTION:When the gate voltage VG of an N gate thyristor 8 is lowered at a low temperature, the thyristor 8 is turned on before the sufficient electric charge is charged to a capacitor 5. Thus the current flowing to a resistance 9 is reduced together with the current flowing to the gate of a thyristor 10. Then the cathode voltage VK is also reduced. As a result, the conduction is impossible with the thyristor 10. In this connection, a Zener diode 3 is inserted to both ends of a temperature dependence resistor 2. Therefore it is possible to eliminate such a problem where the both-end voltage of the resistor 2 is clipped by the diode 3 at <=10 deg.C, for instance, and the thyristor is not triggered. |
