Automobile headlight automatic controller circuit composed of 555

17:00:12As shown in the figure is the automatic control circuit of automobile headlights. The controller consists of a monostable delay circuit (IC1, Rl, R2, RD, C1), a multivibrator (IC2, R3, R4, C2), an integrated voltage stabilizing circuit IC3 (7812), and a V-MOS power drive tube. It is composed of BG2, BG3, etc., which drive the two headlights of the car respectively. The power supply of the controller is powered by the car battery +24V. After being stabilized by IC3, it provides a DC voltage of VDD=+12V to IC1 and IC2.
When there is no vehicle going in the opposite direction in front, the photoresistor RD is high-impedance because it is not exposed to light. The corresponding IC1 is reset because pin ② is high level, and pin ③ outputs low level. This level puts IC2 in a reset state because pin ④ is at low potential. The low level output by pin ③ turns off BG1, turns on BG2 and BG3, and lights up the two headlights.
When there is a vehicle traveling in the opposite direction in front, RD is low-impedance due to being illuminated by the lights of the other vehicle. IC1 is set because pin ② is low level (1/3VDD), and pin ③ outputs high level. The level causes IC2 to start oscillating because the ④ pin is high level, and outputs a square wave signal with an oscillation frequency of f=1.44/(R3+2R4)C: (about 40Hz). At this time, BG1 alternately turns on and off with the high and low levels of the square wave, and correspondingly, BG2 and BG3 alternate between turning off and on, causing the two headlights to flash brightly and darkly. If the light disappears, C1 is charged through R2. When the voltage on C1 is charged to 2/3VDD, IC1 is reset. The charging time of C1 is the delayed flashing time of the headlight td=1.1R2C1. If the delay time is up and RD is still not illuminated, IC1 is in a low level stable state. This low level resets IC2 and the two headlights light up again.

Automobile headlight automatic controller circuit composed of 555