How to interface 12vdc LED vehicle running lights with strobe flasher module

Discussion in 'Automotive Electronics' started by GaryTheBadger, Nov 1, 2018.

  1. GaryTheBadger

    Thread Starter New Member

    Nov 1, 2018
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    Hello, thank you in advance for your help. I install vehicle accessories, especially LED lighting, as a retirement job. I am working on a vehicle that has standard LED running lights at all four corners that are on whenever the ignition is on. I want to integrate a commercial LED strobe flasher module (I already have it on-hand), which simply outputs its 12vdc to drive LEDs at a variety of switchable flashing patterns. THE GOAL IS: When the strobe module is turned OFF, the running lights are constantly on as normal, but when the strobe module is turned ON, it "overrides" the running lights and they flash using the module's switchable pattern. Everything is 12vdc and very low current. It would not be a problem for me to run additional wiring to each of the four running lights, if that is necessary. I am fluent in schematics and electronic circuit building. Is there a way to do this?
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Welcome to AAC!

    Here is a simple solution.

    It will require a power SPST switch to power the LEDs and override the flasher module.
    If you want to eliminate the SPST switch, you will need additional components such as a transistor and resistors.

    vehicle accessory lights.jpg
     
  3. GaryTheBadger

    Thread Starter New Member

    Nov 1, 2018
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    Thank you MrChips. Would it be possible to also see the alternate solution you mentioned, with additional components, if it's not a lot of effort for you?
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    On second thoughts, that is not so easy to do. You need some signal to indicate when the flasher module is turned off. The only thing I can come up with is a circuit that monitors power output from the module (before the diode). When it sees no power (averaged over time) it has to turn on a high-side switch such as a PNP power transistor or a P-channel MOSFET.
     
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Why not a relay with the switch? When the switch is thrown, to activate the flasher, it would also activate a LED next to the switch. That LED would mean the flasher is energized.
     
  6. GaryTheBadger

    Thread Starter New Member

    Nov 1, 2018
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  7. geekoftheweek

    Active Member

    Oct 6, 2013
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    Will work, a bit pricey after doing all four corners, but probably the most reliable and simplest in the long run. Are you doing individual circuits or will they all be enabled / disabled at the same time? A 4 pole 2 toggle relay would be an option if you are doing all corners at the same time for less than $10 (US) and could be wired to turn on when you turn the flasher module on. The nc pin to your normal daytime light circuit, the no pin to your flasher, and the common pin to your lights. I thought of mentioning yesterday I found several on mouser with 12 volt coils, but since a relay was mentioned before a few times I didn't.

    Nevermind... I just re read your original post and found I missed important details.

    I also noticed a 2 second delay mentioned in the page for the device when it returns to normal mode and wondered if that was something that would be an issue for your application.
     
    Last edited: Nov 10, 2018 at 10:42 AM
  8. GaryTheBadger

    Thread Starter New Member

    Nov 1, 2018
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    The two-second delay will not be a problem.
     
  9. geekoftheweek

    Active Member

    Oct 6, 2013
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    I'm kind of tasting shoe leather in a way. Once I put a little more thought into things I realized you are on the right road and probably in the long run the best one to take. Maybe I should stick to learning what I can from this forum and keep most of my comments to myself.

    Good luck
     
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