| 摘要 |
PURPOSE:To decrease the number of parts of a two-stage timer by connecting a charging circuit to the input of a comparator with feedback circuit, and then providing a circuit which applies feedback in comparison and holds the output of said comparator at low level by rising a voltage to the prescribed value. CONSTITUTION:When a timer start signal P is inputted, the charging of a capacitor C1 starts, and its charging voltage is compared with a reference voltage by a comparator C. Then, the comparator C outputs an output signal and a voltage applied to the inverted input terminal of the comparator C rises. At this time, a driving transistor TR2 turns on to power up a load M. Then, when the output voltage of the comparator C rises, a TR1 whose base connects with a Zener diode turns on, and the TR2 turns off, stopping the power supply to the load M. |
