| 摘要 |
PURPOSE:To prevent drop in battery voltage and mistaken operation of an electronic circuit by the arrangement of turning off the lamp when a specified time has passed even if the switch for the lamp is ON continuously. CONSTITUTION:When a switch 13 to light the lamp is ON, timer circuits 5 and 6 start measurement by means of an one-section period signal that is the output of a frequency divider circuit 2, and within 2.5-3.5sec the output of a NAND gate 8 becomes 1, and since the inputs to a NANA gate 9 are both 1, a bipolar transistor has continuity and a lamp 10 is lighted. After 2.5-3.5sec have passed, the input of a clock signal to a timer circuit is prohibited and the lamp 10 is turned off. When a switch 13 of the lamp 10 is OFF, the timer circuit is reset. If the switch 13 is OFF within 2.5-3.5sec, the timer circuit is reset and the lamp 10 is turned off. |
