Led on switch turning off in on position

Discussion in 'The Projects Forum' started by shezza, Jun 22, 2014.

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  1. shezza

    Thread Starter Member

    Mar 19, 2014
    Hi all,

    I want to buy a 3 pin switch with an led.
    I want the led to notify me that the switch is in the open position, not closed.
    Any thoughts as how I would do this? Im stumped...
    Guessing its something easy, but that doesnt mean I can work it out :)

    Last edited: Jun 22, 2014
  2. Billy4184


    Jun 20, 2014
    A 3 pin has two closed states so connect a resistor and LED from the OFF pin to the ground and connect your equipment to the opposite (ON) pin. And connect the power to the middle pin.

    EDIT: misunderstood you. So just connect the power to the middle and a resistor to ground on the side that has the LED. Connect your equipment on the pin opposite the LED.
    Make sure the resistor that goes to ground is the same as the LED series resistor for the voltage you are using.
    Last edited: Jun 22, 2014
  3. shezza

    Thread Starter Member

    Mar 19, 2014
    A 3 pin without an internal led has two closed states. Though with an internal led, there is only one closed state I believe. The third pole is for the + of the led.
    I really wanted one with an in-built led rather rather than an external led. If I have to, then I guess I will live, but there must be a way? Or are there 4 pin switches with an in-built led and two closed states?
  4. Billy4184


    Jun 20, 2014
    Sorry I'm a bit foggy (should have drawn a diagram first!) I don't think it is possible as the off position does not have a terminal out as far as I know. So maybe just hook up your own LED with a two-closed-state switch.
    Why do you need the LED on when it is off? Just read things the other way around...
  5. shezza

    Thread Starter Member

    Mar 19, 2014
    Well the external led was my first thought, but it would just be cleaner with an in-built one.
    I have an auto windows up module in my car for when I leave my car. I am installing a cut off switch in case I want to leave the windows down. Though I want to make sure I remember to re-enable it to not end up leaving my windows down when I want them to go up.
  6. DickCappels


    Aug 21, 2008

    1. Connect the LED to its power supply through the current limiting resistor.
    2. Connect the switch in parallel with the LED.

    When the switch is closed current to the LED will be shunted around the LED by the switch.
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    Pity you mentioned 'car'. Are you aware car mods are banned on this site? Read the Terms of Service.

    Why would you want to leave the windows down? Chances are you wouldn't have a car to return to :)
  8. bertus


    Apr 5, 2008

    I am closing this thread as it violates AAC policy and/or safety issues.

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