Need Simple Circuit to combine Blinker and Marker signals

Discussion in 'The Projects Forum' started by anondrao, Sep 15, 2008.

  1. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    I have a fender LED that has only one lead, and i need to make it possible for it to both light up when the headlights are on and also blink when the blinker is engaged.

    I could see this going two ways:
    1. marker is 50% brightness and it blinks to 100%... or
    2. marker is 100% and it blinks OFF and ON

    please advise

    ~andon
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Assuming LED [D1 ] cathode is grounded and full brightness is 20 mA; head lamp [ H ] ground to 12 V.same with blink [B ]. Try a diode [D 2, D 3 ]resistor OR gate, H to anode D2,cathode to1200 Ω to D 1 ,same way with B. H on 50 %, H & B 50 %+50 % blink. Not tried.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    How is the LED used now? A side marker light that's ON when the headlights are on, or as a turn signal iindicator?
     
  4. Externet

    AAC Fanatic!

    Nov 29, 2005
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    What about...

    +H---R------->|---------J--------led-------R------G

    +B----------->|---------J

    B=blinkers
    H=headlights
    J=junction
    R=resistor
    G=ground
    --->|--- =diode
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Do we know if there is a R from led to G ? As shown if H & B are hi , led will still be bright, only change will be whe both H & B are low. Help Sgt.
     
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Sorry, It will work if either H or B is hi but not both high at the same .time.
     
  7. Externet

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    Nov 29, 2005
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  8. SgtWookie

    Expert

    Jul 17, 2007
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    I haven't seen a response from the OP to my question yet.
    I'm really not willing to run off willy-nilly trying to come up with a solution if I don't know what the full problem statement is.
     
  9. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    Sorry guys, I don't have internet at home for the moment...

    Thank you for your responses!

    I'm putting together a more specific question right now

    thanks again
     
  10. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    I'm using this accent light :
    http://www.superbrightleds.com/specs/mcm.htm

    MCM-A6 (Amber) 40mA @ 12V
    it has 6 LED's

    So i just need to allow that to function as both marker and blinker... thank you!

    Externet : I am reading your posts now...
     
    Last edited: Sep 16, 2008
  11. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    It's not hooked up as either at the moment.
     
  12. Bernard

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    Aug 7, 2008
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    I think we have enough info now. Go back to Externet 8-15 1:55 PM diagram. M ake R about 280 Ω s ;drop R & G from led cathode as it is already G. Should be enough contrast when both H & B are high to see a blink.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Well, it appears that the LED module has a built-in current limiting circuit. Attempting to use a simple resistor to limit current isn't going to work very well.

    Seems to me that you will need to use some sort of PWM scheme. For 50% brightness, your PWM duty cycle will be 50%, and for full brightness, >99% duty cycle.
     
  14. Duxthe1

    New Member

    Sep 27, 2008
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    I built a module using the PIC12f675 to control my add on running light leds on my motorcycle. It powers up the running lights and blinks them off when the t/s is blinked on so that they blink alternately.
     
  15. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    OK... so this is what i'm testing.
    As i've said earlier, I'm using this accent light :
    http://www.superbrightleds.com/specs/mcm.htm

    MCM-A6 (Amber) 40mA @ 12V
    it has 6 LED's
    and has Resistors built in to limit the current to the circuit.

    I just went to radioshack for some parts.

    I purchased two 3A (200PIV) Rectifier Diodes LINK TO RADIOSHACK
    and a package of 2.2kΩ Resistors LINK TO RADIOSHACK

    This is my thinking...
    12V
    B+------>|(3A)----R1(2.2kΩ)-----X---LED(40mA)----|G
    M+----- >|(3A)---------------------X

    (where B+ is blinkers, M+ is markers, >| are 3A diodes, R1 is 2.2kΩ, X denotes a junction, LED is 40mA, and G is common ground)

    Currently i have the LED + to my 2.2kΩ Resistor and then to 12V+ and the LED - to ground...
    It's been hooked up for 15 minutes and does not appear to be getting hot at all... i can touch it and it feels like the temperature of the Resistor hasn't changed.

    Ideally I want to have the most efficient and stable circuit possible as I would like to publish the solution to help others seeking to resolve this issue.
     
    Last edited: Oct 1, 2008
  16. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    I would love to know more about this solution!
     
  17. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    So... i'm thinking the 3A Diode is a bit overkill... I have also 75mA Diodes that would do just fine.
     
  18. anondrao

    Thread Starter New Member

    Sep 15, 2008
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    Any input would be greatly appreciated... For ease of construction i figured the axial diodes would fine... would a bridge rectifier be better?
     
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