Help with LED tail light/brake light

Discussion in 'The Projects Forum' started by Pilotdan, Jan 2, 2013.

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  1. Pilotdan

    Thread Starter New Member

    Jan 2, 2013
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    Hello all. I am new to this foum and very inexperienced with electricity. I would like to make an LED tail light/brake light for my motorcycle. I was looking at a YouTube video that explained how to figure how many LED's to each resistor. But what I am trying to figure out is how do you make the LED's go from dim or medium intensity when it's the tail light to bright intensity for the brake light. Are there special LED's for this or is it just the power settings. Any help or advice would be greatly appreciated. Thank you.
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,986
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    Vary the current through the leds by using a constant current driver like the LM317 regulator
    http://users.telenet.be/davshomepage/current-source.htm


    each led will take approx 1.8 volts and the regulator drops approx 3v, so thats 4 leds for each regulator will give good brightness. To vary the brightness alter the resistor value, smaller is brighter, bigger is dimmer
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The LM317 is not suitable nor is rated for automotive environments.
    The 1.8V Vf would be for very old red LEDs that would not be suitable for use in a taillight.
    Besides, plain red is not the proper color for taillights in the US.

    Pilotdan,
    Welcome to the Forums. Unfortunately, your topic has run afoul of the Terms of Service, which is located here:
    http://www.allaboutcircuits.com/l_tos.html
    in particular, paragraph 6, which reads:

    As your topic is classified as an "Automotive modification", discussion of it on the Forums is not supported. The decision to restrict the above list of topics was made by the Owners of the Board, and they are not open to changes nor to make any exceptions to the list.

    If you feel that you must pursue your project, there are a few selected forums linked to in a topic in the Electronic Resources section. However, I will strongly recommend that you not attempt to modify your vehicle's running lights, as you are likely to create a large safety hazard for yourself.
     
  4. Georacer

    Moderator

    Nov 25, 2009
    5,142
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