Non polar LED wiring components

Discussion in 'General Electronics Chat' started by gunship800, Sep 13, 2012.

  1. gunship800

    Thread Starter New Member

    Jul 19, 2012
    I'm working with a car radio face plate. You can apply voltage in either direction and have all the button incandescent bulbs turn on.

    Behind the LCD panel there are two bulbs on their own circuit. Again, you can apply 12+ or negative to either lead and have the bulbs come on.

    I am trying to put two LEDs with their own resistors in place of the LCD bulbs.

    Problem is, I don't know which side the factory radio provides + and - to and there's no way for me to find out.

    I can't seem to find the component that I need in order for the LED/resistor to power on regardless of which direction the + /- is coming into it.

    I've been looking at rectifiers and diode bridges, but that doesn't seem to be the right thing. I need something that is small. About the size of a 1210 smd LED
  2. #12


    Nov 30, 2010
  3. MrChips


    Oct 2, 2009
    Put two LEDs in parallel but in opposite direction with each other.
    #12 likes this.
  4. #12


    Nov 30, 2010
    Taking that to the next level, a bi-color LED with 2 leads. It' already 2 LEDs that will protect each other from reversed voltage, they only take up the space of one LED and no diodes, and if you get something backwards, the only penalty is that you get a different color.
  5. sdowney717

    Well-Known Member

    Jul 18, 2012
    I have bought some AC LED pilot lights from Ebay that are Chinese made and work well.
    I slid the LED out of the plastic holder and saw that one lead has a tiny resistor and the other has a tiny black diode soldered on. The LED must be lighting up on one side of the sine wave and not the other.

    The DC ones only have a single resistor on one of the leads to drop the voltage-current. I found their DC ones were too bright due to them not having enough resistance and they tended to burn out. So I added a tiny resistor in on of the wire leads.

    Why would your LED be damaged if the polarity is reversed if your limiting the current it just wont light up.

    Neowedge LED bulbs with bases are for sale and I have seen many cars using that socket. They come in 3 sizes. They are made to replace the twist lock snap in small dash lights.