Converting LED Turn Signals into Sequential Signals (Show Only)

Discussion in 'Automotive Electronics' started by ACollins, Feb 11, 2016.

  1. ACollins

    Thread Starter New Member

    Feb 11, 2016
    3
    0
    Hi all,

    Before I begin, to mitigate replies about not altering exterior vehicle lighting, etc... This project is for show only and not intended for road use, no ordinances against it, not breaking any codes, all that jazz...
    I have a show car with a set of aftermarket tail lights, and the turn signals consist of 16 LEDs arranged in an arrow in the direction of turn.
    With the current arrangement they all blink simultaneously like a normal signal.
    What I'm trying to do is to get them to stack/chase with each blink, i.e. LEDs go 1 - 1,2 - 1,2,3 - 1,2,3,4 - 1,2,3,4,5 [...] 1,...,16 then after a pause, repeat.
    I found some ways to get them to sequence with a 555 timer and two 4017 ICs but I'm not sure how or whether they'd stack as well. Unfortunately my digital-electronics knowledge has all but faded away since school. I've seen a you-tube video with the same lights made to be sequential but the author hasn't responded to my inquiries about the setup.

    Any help would be much appreciated.

    Thanks.

    -AC
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    The tricky part is doing the 16 different sequences in order.
    Not sure there's an easy way to do that without a microprocessor to control everything.
     
  3. ACollins

    Thread Starter New Member

    Feb 11, 2016
    3
    0
    I've thought about getting some ARDUINO UNOs for it, but was hoping there could be a simpler/cheaper option since I'm really only looking for the one sequence.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    Maybe you can using two LM3914 to do.
     
  5. ACollins

    Thread Starter New Member

    Feb 11, 2016
    3
    0
    I'm not sure if this helps at all but this is what I'm looking to make, I'm a visual person so this makes more sense to me than trying to type it out.
    Turn signals already have a relay to flash ON/OFF, so I'm looking to build a circuit that interrupts that signal to the LEDs and translates the ON pulse to:
    o- - - - - - - - - - - - - - -
    oo- - - - - - - - - - - - - -
    ooo- - - - - - - - - - - - -
    oooo- - - - - - - - - - - -
    ooooo- - - - - - - - - - -
    oooooo- - - - - - - - - -
    ooooooo- - - - - - - - -
    oooooooo- - - - - - - -
    ooooooooo- - - - - - -
    oooooooooo- - - - - -
    ooooooooooo- - - - -
    oooooooooooo- - - -
    ooooooooooooo- - -
    oooooooooooooo- -
    ooooooooooooooo-
    oooooooooooooooo
    Then during the OFF pulse:
    - - - - - - - - - - - - - - - -
    Then it switches ON again and the cycle repeats.

    Essentially, I want a circuit that when power is applied, lights up a row of LEDs 1 by 1 until they're all lit.

    The closest I've seen is a circuit with a 555 timer and two 4017s that would create the following:
    - - - - - - - - - - - - - - - -
    o- - - - - - - - - - - - - - -
    oo- - - - - - - - - - - - - -
    -oo - - - - - - - - - - - - -
    - -oo - - - - - - - - - - - -
    - - -oo - - - - - - - - - - -
    - - - -oo - - - - - - - - - -
    (and so on and so forth)
    Which is still nice, just not quite what I'm looking for.

    I feel like it should be simple enough and I'd like to avoid using microcontrollers if possible. I can throw together circuits from schematics, though I may not be able to understand them fully.
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    It appears simple enough in concept, but the discrete logic to do it does not appear to be.
    I think you are probably talking a dozen chips or so with a lot of wiring.
    Cutting it back to an 8 or 10 light sequence would help a lot.
     
  7. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,809
    834
    It appears that you plan on using the existing LED array... Note that it may not be wired to be compatible with the sequence you propose. Each row must be able to be independently controlled.
     
  8. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    There was a thread few years ago about this but I couldn't find it but I still kept the schematics.

    It uses 2 x 74HC164 to display 16 LED with pulses from a 555. It would be best to drive the LED through LED drivers like ULN2804 to prevent the HC164 getting overheat. This circuit operates on 5V.

    Not sure if there is a CMOS equilvalent of HC164, so the whole circuit can be operated on 12V DC.

    ACOLLINS HC164 LED 90%.PNG
    Allen
     
    ScottWang likes this.
  9. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    absf likes this.
  10. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    I think I misunderstood your requirements. :rolleyes:
    At first I thought you wanted to reset between each partial sequence.
    So if you just want to light all 16 LEDs in sequence then afsf's circuit or some variant should work for you.
     
  11. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    Me too.
    >>What I'm trying to do is to get them to stack/chase with each blink

    So I think maybe the TS want a shift and blink function, actually he just want the shifting function, a slowly sawtooth wave and two LM3914 can do as the shifting function.
     
  12. hp1729

    Well-Known Member

    Nov 23, 2015
    1,954
    219
    How were you going to handle the arrow at the end? A smart solution (like Arduino) gives many options.
     
  13. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,541
    1,251
    Blink is an ambiguous term. As the pattern travels across the LED array, do you want all LEDs to turn off briefly between each successive stage, adding a flutter effect to the display, or move straight through the pattern with all previously lit LEDs staying on continuously as the pattern progresses?

    There is another blinking LED thread on this forum with a slightly different pattern. Depending on the LED current needed for your required brightness, I have a suggestion for LED drivers.

    ak
     
Loading...