| 摘要 |
PURPOSE:To reduce the time required for discharge and to achieve accurate operation of a timer, by discharging through a thyristor connected in parallel with a capacitor. CONSTITUTION:When a switch 13' is closed with no charge in a capacitor 1', a transistor (TR) 3' turns on only with a time determined by the time constant of the capacitor 1' and a discharge resistor 2' for operation of a timer. After a prescribed time of turning on/off of the TR3', the gate and anode of a thyristor 11 are biased reversely owing to a drop voltage by a diode 12 to keep turn off the thyristor 11. When the switch 13' is opened, a current flows between the anode and gate with the charge in the capacitor 1' to turn on the thyristor 11, resulting that the capacitor is rapidly discharged. Thus, inaccurate operation of the timer due to remained charge in the capacitor can be avoided. |
