2 wire LEDs used as Brake-Tail

Discussion in 'The Projects Forum' started by jbhawley, Jan 22, 2010.

  1. jbhawley

    Thread Starter New Member

    Jan 22, 2010
    Hello all. This is my first posting on this forum so please forgive me ahead of time if you have answered this questions many times. I have spent the past couple hours searching this forum for my specific item, but either have not found a relevant solution or the solution posted was waaaay over my head.

    I have a pull behind trailer that has a standard 5 wire connection coming from the vehicle. Ground, Right Turn, Left Turn, Brake and Tail (run). I have added an extension to the trailer and need to add some additional rear lighting. I have purchased these:

    They are simple LED lightbars that have a two wire system. Hot/ground. I have the amber colored lights for each turn signal. This was the easy part..just tap into the existing left and right turn wiring. The red LED bar I would like to use as a brake and turn. I have two red light bars mounted, one under each turn (amber) bar. Sorry, but I do not have any additional info on the lights as they are a sealed unit with no specs sheets.

    From additional reading on this forum, mentioned is 555 boards, resistors, PWM circuits and so forth. Honestly this is a bit over my head. I am a definite noob on circuit boards, so far as building them. As I understand I need to get the LEDs to stay dim while on tail (run) and then go brighter when the brake is applied.

    Is there a simple solution to make my idea work without having to reinvent the wheel?

    Many thanks for suggestions. I have attached a very simple diagram of the set up.
  2. Bernard


    Aug 7, 2008
    Just a thought: Three input OR gate, T current limited by 50 ohm +-, B passes thru shottky diode & P ch MOSFET which is always on if B is on to red;L direct connection to amber & gate, which inhibits B & T while L is flashing, if B is off L lights red. Same ckt for R. Gste resistor about 1k.
  3. jbhawley

    Thread Starter New Member

    Jan 22, 2010
    I think I figured it out. Being a noob to this, i went to Radio Shack adn purchased a couple diodes and some resistors. Total cost less than 10$. I knew I needed a diode to "block" the backfeed current that would come from the brake lite. I experimented with the resistor to "lessen" the current coming into the LED with the tail lite was on. Then when applying the brake the LED lit to 100%. It took a bit of tinkering but works good now.
    Here is a real simple image of my set up.
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