Need guidance with wiring 12V motorcycle running/brake light

Discussion in 'Off-Topic' started by 20_rc51_00, Oct 30, 2014.

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  1. 20_rc51_00

    Thread Starter New Member

    Oct 30, 2014
    I have been searching the net for a way to wire some custom LED running/brake lights I have made. I know there is a right way to do it and a way that might work, I'd rather do it right.


    I am using Agilent HPWT-DH00 H34 LED's Vf=2.55-2.79
    I planned on using KA378R12C to provide a constant 12V while the vehicle is running and providing anywhere 12.5+ to 14.7V This version is also LDO so it wouldn't require too much overhead and allow me to link 4LED in series with minimal wattage resistors
    I also purchased this PWM in hopes of dimming for the running lights vs the brighter brake light setting.

    the lights will have 2 pcb panels with 24LED each arranged in 6 parallel strings of 4LED's.

    I was going to use one 12V reg for the running light function and another for the brake function. Using the 12v output from the dedicated running light regulator to power the PWM I have had trouble when I connect the brake light ground and the PWM load ground since the dimmed light will brighten to its intended brake light setting...

    In the past ( my current and working tail/brake lights for the past 10 yrs) I used a 9V regulator that had 3 pins to power a similar setup but was using cheap 5mm LED's from ebay. I wanted to step everything up in this build. My confusion stems from not knowing how to properly utilize the KA378R12C and how to wire the pins. In my old setup I just had straight power supplied from the bike to the In-Pin, LED's powered by the Out-Pin, and the third ground connected straight to the ground.... It worked but I know that I don't want to do it like that here. If there is any advice how to go about wiring this 12V regulator I would greatly appreciate it.

    I have attached a pic of a crude diagram representing my current breadboard.

  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    You should read item 6 here.

    Ask your question here.
  3. MrChips


    Oct 2, 2009
    The owners of All About Circuits have elected not to allow discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

    This thread is against the AAC forum rules, Chapter 6, as seen here:

    This can be found in our Terms of Service (ToS)

    Here is a site that may provide you with some assistance: Electro Tech Online

    Good luck.
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