Pulsing LED Third Brake Light

How its works ?

Its pretty simple. As soon as you hit the brakes Third Brake light will flash at 20Hz.
And after 3 seconds Third Brake light will be Steady on.

Why Pulsing Third Brake Light ?

Because This will help get the attention of the drivers following behind you.
Even when your in bumper to bumper traffic.


DO NOT CONNECT THIS CIRCUIT TO YOUR MAIN BRAKE LIGHTS. Any type of flashing light on the main brake lights is prohibited and illegal. Use this circuit at your own risk and be aware that the possibility exists to be stopped by law enforcement if you implement this circuit in your vehicle.

Pulse Train Graph for better understanding

Schematics in jpeg format

Schematics and HEX File for PIC12F675

About pasanlaksiri

I am K.G. Pasan Laksiri Karunanayake and founder of OptoElectronics.lk. Since 2011 I have specialized in designing custom electronics for industrial applications. Over the years I have engineered a broad range of custom industrial products. When I work with a client I place a very high value on integrity, honesty and clear communication. With years of field experience I have learned that all business relationships are personal relationships. The more I know about the client and his project, the more I can contribute to a successful end product. After I learn about the client requirement I always give them the better understanding and clear picture about, how the end product will function in real world. In addition to the client requirement, I also offer lots of options, features and improvements. And I always very concern about the end product quality.
This entry was posted in Digital Electronics. Bookmark the permalink.

8 Responses to Pulsing LED Third Brake Light

  1. Søren says:


    Why bother with the flashing when you’re so close to the cinematic rate of 24Hz?
    To really make it visible, as an emergency flasher ought to be, it shouldn’t be more than 3Hz to 5Hz.


    • pasanlaksiri says:

      Yes agreed. But I like the look when its flashing at 22Hz. Its more like a strobe. heh heh heee.


      • Søren says:


        With say 3 of the unused pins, you could make the flash rate switch selectable (or strap-able) to cater for 8 rates from 3 Hz up.

        To make it really easy, you coud go in equal steps like 3Hz, 6Hz, 9Hz, 12Hz, 15Hz, 18Hz, 21Hz, or something similar.

        Just suggestions of course, not meant negative in any way.


  2. pasanlaksiri says:

    Thank you very much for the suggestions. Im currently working on interfacing HT1632 display driver. So I i’ll edit this project little later.


  3. Victor says:

    hello pasanlaksiri, I’m interested in this project, and before I begin, I want to ask if the circuit is ok. I ask this because in the pictures, I see that there are other components. Thank you and hope you do not mind.


    • pasanlaksiri says:

      Hi Victor,

      The only extra component is ULN2003 current sinking chip. You can test the cct with one LED connected to 7th pin of the MCU across some resistor like 180ohm or so.


  4. Victor says:

    ok. I will try to realize the proposed scheme.
    ‘ll let you know if I succeeded or not.


  5. mustafa says:

    Hello.I don’t see pics and code.thanks.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s