0 Car Brake Light Circuit


A simple tail and brake light circuit for cars and vehicles using LED. When the vehicle is slowing down, switch s1 will be closed and LED will illuminate in low light. The LEDs will consume about 10mA each. When brake is applied, the switch s2 will closed and allowing the LED to illuminate at full brightness. This time the LEDs will consume 25mA current each. The circuit employs a constant current method, the same method used in the cheap power led driver circuit.
The current drawn by every LED is given by the simple equations:
Current on slowing down = 0.3/R2; and Current on brake = 0.3/R3  all current in Amperes


brake light circuit
2N2222 pinout
Part List:
R1 - 1.2 kilo ohms 1/4W
R2 - 30 ohms 1/4W
R3 - 12 ohms 1/4W
D1, D2 - 1N4001, 1N4004 or similar silicon diode
LED - red LED (3mm or 5mm) or any low power LED of your choice
Q1 - 2N2222, CS9013 or similar NPN transistor (higher power the better)
Bat - 12V car battery

Note: If your are planing to use power LEDs or modify the circuit to cater more LEDs, just replace the transistor with higher power capacity, and replace the values of R2 and R3 using the formula presented above.

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