Motorcycle brake light delayed turn off circuit diagram

When a fast-moving motorcycle encounters an unexpected situation or needs to turn, it needs to use the foot brake to slow down or stop the vehicle. Generally, the brake light on a motorcycle will come on after the foot brake is applied. Once the brake is reset, the brake light will go out. , in this way, it is not easy to attract the attention of vehicles behind. If this circuit is installed on a motorcycle, the brake light of the motorcycle can be delayed for a few seconds after the brake is reset like a car light to remind the vehicles behind to pay attention. This has practical significance for traffic safety and reducing traffic accidents. .

The circuit principle is as shown in the figure: S1 is the power switch, controlled by the car lock, and S2 is the original brake light control switch. Close the switch S1. Since the voltage across the capacitor C1 cannot change suddenly, pin 2 of the IC is at low level and the brake light H lights up. After a few seconds, because C1 is discharged, when the voltage of pin 2 of the IC is higher than 1.6V, the light H goes out. When the moving motorcycle encounters a situation and decelerates or stops, the switch S2 is closed to short-circuit the two ends of C1 and discharge, causing the switch IC's pin 2 to become low level. The brake light H is then lit. After S2 is reset, H must It will turn off after a few seconds of delay.

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The IC in the circuit is a high-power switch integrated circuit TWH8752. The maximum allowable current is 4A. H is the rear brake light . R1 is 470K. C1 uses a 16V, 47uF electrolytic capacitor. C2 uses a 25V, 2200uF electrolytic capacitor. VD1 uses a 1N5408 type. rectifier diode. If you need to change the delay time, you can change the values ​​of R1 and C1 appropriately.