How can I build a display of LED emergency dash lights?

Discussion in 'General Electronics Chat' started by Lefty_Covington, Feb 18, 2010.

  1. Lefty_Covington

    Thread Starter New Member

    Feb 18, 2010

    How can I build a display of LED lights?
    I sell emergency vehicle lights. I would like to be able select one model at a time (similar to car stereo displays commonly found in retail stores). The display would be a wall with a push button switch that would power 12vdc cigarette lighter outlet. I only want one unit to be powered at a time. Could I do this with momentary switches and a type of relay circuit?
  2. Wendy


    Mar 24, 2008
  3. retched

    AAC Fanatic!

    Dec 5, 2009
    You want to build a display that allows the customer to select between each light.

    So your vehicle lights run off of 12VDC, correct? So you could build a board that is full of momentary buttons. You can wire all the lights positives together and connected to your power supplies positive. The negatives(ground) from each light would run to its own button, then from the button to the -(ground) of the power supply.

    That allows the button to complete the circuit for the light while the button is pressed. When released, the light goes out.
    A button like this:

    You can buy lighted buttons, or buttons that light while being held down.

    If you want the button to stay on until another is pressed, that would be a little more complicated.
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    There are, or were, ganged switch banks which mechanically reset all positions except for selected one, or can be done electronically.
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
    How many positions?
    What is current draw per position?
    It's down to a big? OR gate & an R-S latch per position & drivers.
    Last edited: Feb 22, 2010
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
    Here is a sample of a voting ckt. Each LED represents one display , each display needs a NOR latch, one position on OR gate [IC 4048 can be used as 8 inputs & is expandable ] & a NO switch. SWs can be debounced with another set of latches if desired. Pressing any SW resets all latches,then sets the selected latch because of the longer RC time constant[.1uF, 10k]. Flip-flops 4013, 4027, or 4043 with 4 latches could also be used. MOSFETs can be used to drive displays. Nite that 220 ohm resistors are really 2.2k, not verry bright, but proovs point.