17:00:12 as shown in the figure is the car headlight automatic control circuit. The controller consists of a one-shot delay circuit (IC1, Rl, R2, RD, C1), a multivibrator (IC2, R3, R4, C2), an integrated voltage regulator circuit IC3 (7812), and a V-MOS power driver tube. BG2, BG3 and other components, respectively, drive the two headlights of the car. The controller's power supply is powered by the car battery +24V, and is regulated by IC3 to provide DC voltage of VDD=+12V for IC1 and IC2.
When the current side has no opposite vehicle, the photoresistor RD is high impedance due to no illumination, and the corresponding IC1 is reset due to the high level of the 2 pin, and the 3 pin outputs the low level. This level causes IC2 to be in a reset state due to the low potential of pin 4, and the low level of the output of pin 3 causes BG1 to be turned off, BG2 and BG3 are turned on, and the two headlights are turned on.
When the current side has a vehicle facing the line, the RD is low-resistance due to the illumination of the other vehicle. IC1 is set because the 2 pin is low (1/3VDD), and the 3 pin outputs a high level. The IC2 starts to oscillate because the 4-pin is high, and outputs a square wave signal with an oscillation frequency of f=1.44/(R3+2R4)C: (about 40 Hz). At this time, BG1 alternately turns on and off with the high and low levels of the square wave, and the corresponding BG2 and BG3 alternately turn off and turn on, so that the two headlights flash in a clear light. 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 time td=1.1R2C1 of the headlight delay flashing. If the delay time is up and the RD is still not illuminated, IC1 is in a low level steady state. This low level resets IC2 and the two headlights are lit again.
Automobile headlight automatic controller circuit composed of 555
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