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  • Turn Signal/Parking Lights Help

    My idea for this is to rebuild the turn signal/parking light with an LED array, replacing the stock incandescent bulb. I'm planning on using amber Cree P4 LEDs.

    The problem is that I don't know how to enable the LEDs to do dual brightness....I can get them to work for parking lights, and for turn signals, but how do I do both without over powering them/using a microprocessor?

    I've been trying to follow this: http://www.hidplanet.com/forums/show...Pictures/page9

    but I don't quite understand it.

    As it comes from the car (Civic Si), I believe the turn signals get pulsed 12 volts, but I'm not sure of the parking lights. Could it be 12 volts also, but with a lower wattage filament? The bulb used stock is a 3457.

    Thanks!
    2006 Civic Si FG2 // K20 Master Race

  • #2
    The Cheaper way (not recommended)
    Set up your array with the right resistors for full brightness for turn signals.
    Then add a big honkin' resistor to the parking lights for "dimmed" output. The resistor size determines how dim you want it.
    (I did this on this thread, see image on post #7 for wiring part)

    The Better Way (recommended)
    Set up your array with the right resistors for full brightness for turn signals.
    Use a PWM for the dimming of LEDs for parking lights.

    Comment


    • #3
      ^exactly

      The best way (most efficient and reliable) is to use a PWM in conjunction with a 4-pin voltage regulator. Really, the regulator should be used regardless of the dimming method you choose.

      I was planning on writing a fully-detailed description of how the PWM interacts with the the regulator and, in turn, dims the LEDs but I didn't want to scare you away from the method. It's really quite simple once the concept is understood, and I'll be glad to help you through your project. If you're interested in making your own PWM circuit, or just understanding how it all works, just say so and I'll post that lengthy description!

      Edit: the post you've been trying to follow uses LM317s, which are basic adjustable regulators. Components R1 and R2 are used to set the output voltage of the LM317s, and R3 is the "big honkin' resistor" that dims the array for running light use. R4 is the current-limiting resistor for each LED series string. C1 and C2 are input/output smoothing capacitors for the LM317s.
      Last edited by sprengBoard; April 15th, 2015, 05:15 PM.

      Comment


      • #4
        You are not wrong, pulse width is the best way to do it. I understand the concept, but have no clue how to do the execution....I mean, I can build the circuit if it is shown to me, but I have no clue how to design the circuit.

        I'll gladly listen and follow, I just want the simplest, most reliable method of doing this as possible.
        2006 Civic Si FG2 // K20 Master Race

        Comment


        • #5
          Originally posted by sprengBoard View Post
          ^exactly

          The best way (most efficient and reliable) is to use a PWM in conjunction with a 4-pin voltage regulator. Really, the regulator should be used regardless of the dimming method you choose.

          I was planning on writing a fully-detailed description of how the PWM interacts with the the regulator and, in turn, dims the LEDs but I didn't want to scare you away from the method. It's really quite simple once the concept is understood, and I'll be glad to help you through your project. If you're interested in making your own PWM circuit, or just understanding how it all works, just say so and I'll post that lengthy description!

          Edit: the post you've been trying to follow uses LM317s, which are basic adjustable regulators. Components R1 and R2 are used to set the output voltage of the LM317s, and R3 is the "big honkin' resistor" that dims the array for running light use. R4 is the current-limiting resistor for each LED series string. C1 and C2 are input/output smoothing capacitors for the LM317s.
          Feel free to write these how-to novels and put them on your website, maybe a few pics/videos? *hint hint*

          Comment


          • #6
            Originally posted by trentb View Post
            Feel free to write these how-to novels and put them on your website, maybe a few pics/videos? *hint hint*
            I was just thinking the same thing earlier today

            Comment


            • #7
              All this info is in the lumiled superflux datasheets/design considerations. It's always a good idea to read the datasheets.
              Last edited by sall; April 16th, 2015, 07:14 AM.

              Comment


              • #8
                @Sall....the problem isn't finding the information, I need to know how to make the circuit itself, like, how do I make the PWM controller?

                @sprengboard...any tips?
                2006 Civic Si FG2 // K20 Master Race

                Comment


                • #9
                  The PWM circuit is in the datasheets and all around the forum. Simple PWM tutorials all over youtube as well. Even peoples boards posted in threads you could literally copy. Always the option of paying someone to do it or purchasing a stand alone PWM from somewhere like quikar or diode dynamics.

                  PWM circuit and explanation page 22:
                  http://www.lumileds.com/uploads/208/AB20-3-pdf

                  From the long lost AZDave:

                  Comment


                  • #10
                    Hello!

                    So it has been a while since I've asked here, but I need help again.

                    So far, I am going to be using PWM dimming methods as detailed in the above PDF on page 22 (Thanks, Sall!) but now my question is: how do I find the values?

                    Meaning, I am going to be making this: Capture.PNG.

                    How do I know what Rstop and Rtail become? I've looked further into the data sheet and see this: Capture2.PNG

                    The data sheet says that Rstop can be found using the equation immediately above, but how do I get the values from the LED for those values? And, Rtail is solved the same way, taking into consideration the extra drop across the transistor...how do I find that?

                    Also, I'm assuming this is a PNP Darlington Transistor. Can I use any PNP Darlington?

                    Thanks!
                    2006 Civic Si FG2 // K20 Master Race

                    Comment

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