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I need a relay or something

Discussion in 'General Electronics Discussion' started by zogthegreat, Sep 15, 2016.

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  1. zogthegreat

    zogthegreat

    1
    0
    Sep 15, 2016
    Hi everyone!

    I have a bike rack on my 2011 Ford Taurus that I want to install a light that activates when I step on the brakes. Due to the way Ford setup the lights on the Taurus, I can't just tap into the brake lights in the rear. I did manage to tap into the brake light that is in the back window, but due to voltage drop, I'm only getting 6v at the end of the wire. Since I already have a 12v hot wire running to my trailer wiring, what I would like to do is have the wire that comes from the rear window brake light run to some kind of relay or switch to the 12v hot and then from the 12v hot to the bike rack.

    Does anyone have any suggestions?

    Thanks!

    zog
     
  2. duke37

    duke37

    5,361
    767
    Jan 9, 2011
    Just use a mosfet with the gate driven by the brake signal. It should have a capability of 10A or so.
    The gate should be connected via a resistor, say 10k to 100k and a pair of diodes to restrict the gate to between 0V and 12V.
     
  3. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    While I really don't understand why you're getting a 6V voltage drop at the hatch light I believe you're asking for this...

    Chris
    upload_2016-9-16_10-31-23.png
     
  4. Herschel Peeler

    Herschel Peeler

    401
    65
    Feb 21, 2016
    You gave a trailer wiring without a brake light going through it?
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Here's another version that includes a Gate Zener. It can be a Zener voltage of 9V - 12V. It will absorb both positive and negative spikes.

    Chris
    upload_2016-9-16_10-49-48.png
     
  6. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Ha, I didn't catch that. It doesn't make any sense. Does it?

    Chris
     
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