| 摘要 |
<p>PURPOSE:To automatically light and extinguish a front lamp using a digital counter IC. CONSTITUTION:When a vehicle is stopped with a vehicle speed sensor generating H pulses, the clear terminal of a left counter IC shown in the drawing receives the signal of H pulses from the vehicle speed sensor via an inverter and stops the counting action, however, the clear terminal of a right counter IC receives the H signal and therefore starts the counting action. When ripple carry is generated, it runs across a self-holding circuit and the inverter and cuts off a power supply. The lamp of the vehicle is then turned off. When the vehicle starts, the pulse is turned to L to reset the self-holding circuit to light the lamp. During driving, the counter IC is reset cyclicly by the pulse from the vehicle speed sensor so that the lamp is kept lighted. When the vehicle is stopped with the L pulse generated, the left counter IC starts counting and a relay power supply is turned off to extinguish the lamp.</p> |
