Warning LED light car front
Warning light with three yellow 10mm LEDs mounted under the bumper of car.

On my old car, a Subaru Legacy, I built and installed warning lights on all sides. Never really used them, but it was a fun build. I had a total of 8 LED warning lights, all around the car. The lights on the side was used as side markers when not flashing. I originally used the red break light as the rear warning light, but later replaced it with two self-built warning lights.

Table of content


I used self-built LED warning lights in the front and rear, while the side lights were regular side markers. When the warning lights were not flashing; the side markers lit continuously at 10% duty cycle. And then the car started the front side markers would fade in, then the rear, it looked kind of cool from the side :)

The front warning lights split the patterns between them, so alternating from side to side. While the side and rear lights flashed together. The module was originally designed to use the cars additional break light, that is why the rear output is a bit different from the rest. It has two transistors and gives out 12V, while the rest are open collector.

The signal to activate the warning lights came from another microcontroller module I built for the car; a controller for the additional headlights I installed.



  1. PD6 Activate flash signal (optocoupler)


  1. PB0 Rear light
  2. PB1 Front light 1
  3. PB2 Front light 2
  4. PB3 Yellow side light 1 (PWM)
  5. PB4 Yellow side light 2 (PWM)

Connector for LEDs

Pluggable LED connector
Pluggable terminal block for 12V LED lights.

To make it easy to connect to different LED lights I used a pluggable terminal connector.


Schematic drawing

Strobe light controller circuit
Schematic drawing for warning strobe light controller; with AVR ATtiny2313.

Source code


Strobe light controller, meant for cars, written with BASCOM-AVR.

Master Releases

0 0 0 v1.1 Visual Basic 4 months ago

Image gallery

Parts list

Project: Warning strobe light controller for car by Thomas Jensen is licensed under CC BY-SA 4.0 with attribution required.

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  •   Created May 21, 2009
  •   Last modified 5 days ago
  • Project status: Scrapped