Simple LED setup has a short circuit?

Discussion in 'Replica Props' started by MrSinistar, Dec 24, 2011.

  1. MrSinistar

    MrSinistar Well-Known Member

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    I just finished my first soldering job by attaching a Red LED to a 150 ohms resistor, to a switch and then to a 2032 battery. Everything powers on fine and stuff, but after less than a day, the battery is completely dead. What's happening that's causing the battery to leak its power while it's off?
     
  2. robstyle

    robstyle Sr Member

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    can you post a picture of the connections and the switch.

    Is it a three way switch?

    In place of replacing parts, I always suggest a dollar store flashlight for these things. Take it apart, run longer wires if need be, done.
     
  3. MrSinistar

    MrSinistar Well-Known Member

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    Hi Rob,

    I uploaded the pics. I think the switch is two-way since it has two terminals. I do have a switch with three terminals for my Blade Runner Blaster and I don't know how to wire that up, so we can get two bird with one stone, that would be awesome. XD

    Thanks for the tip on Dollar store flashlights...I don't know why I didn't think of that, lol.

    EDIT: Pics uploaded...sorry about my thumbs...I ended up cutting myself while working on a Christmas present model kit, lol
     
    Last edited: Dec 25, 2011
  4. MrSinistar

    MrSinistar Well-Known Member

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  5. stromo

    stromo Well-Known Member

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    It looks like you're shorting the battery when you switch that off. Disconnect everything from the switch then do this:
    1. Connect red wire to one terminal.
    2. Connect resistor to other terminal.
    3. Solder both black wires together.

    Of course you'll need a new battery, but you already know that.
     
  6. Fyberdyne Labs

    Fyberdyne Labs Well-Known Member

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    I agree with stromo. If you need a 2nd openion.
    Mark
     
  7. MrSinistar

    MrSinistar Well-Known Member

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    Thanks, stromo. When you say red [positive] wire, do you mean the whole positive side of the circuit? Including the positive lead on the LED?

    If you can do a drawing or go into detail, I would really appreciate it, since I know very little in electronics. Thanks
     
  8. MrSinistar

    MrSinistar Well-Known Member

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    Is this what you want me to do, stromo?
     
  9. Construct

    Construct New Member

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    On these, pushing the slide to the left connects the left and centre terminals whilst pushing the slide to the right connects the right and centre terminals. So you can, say, connect a different colour LED to each side and switch between the two - or leave one side unconnected to have just an on/off switch like now.

    Got it in one. :thumbsup
     
  10. MrSinistar

    MrSinistar Well-Known Member

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    Ahhhh!! Makes perfect sense now. Thanks guys!

    And just to doublecheck, I can do the exact same thing with five LEDs hooked up together, right? All I need to do in that scenario is compensate with a bigger resistor, right? I know there's parallel and serial circuits and stuff like that, but I wanted to hear what your opinion is and stuff, lol. Okay, I'm getting tired, just thinking about this stuff (it doesn't help that it's 3:30 in the morning too), lol
     
  11. stromo

    stromo Well-Known Member

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    Actually, you can leave the resistor on the LED side of the switch, but this would work too. It really doesn't matter where you break the circuit.
     
  12. stromo

    stromo Well-Known Member

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    This is what I originally intended:

    [​IMG]

    Given that you're thinking of putting several in parallel, I'd recommend you keep the resistors on the LED side of the switch, as in this picture. Make sure each LED has its own resistor, or you'll end up with some LEDs brighter than others.
     
  13. MrSinistar

    MrSinistar Well-Known Member

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    Okay, great; I'll go ahead and leave the resistor where it is.
     
  14. stromo

    stromo Well-Known Member

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    OK, I just did you a quick picture of what five LEDs in parallel would look like:

    [​IMG]

    But I have to say if you're going to try to run five LEDs off of one button cell, you'll need to lower the resistor values dramatically. You may even need to increase the voltage somewhat (adding more cells in series).
     
  15. robstyle

    robstyle Sr Member

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    You can pick up LED flashlights with 5 LED's in them at the dollar stores. The individual LED's are usually sold as reading lights and have an actual switch where the flashlights have that cheap plastic make shift switch. 99% of the time the LED's will be a super bright white. These are outstanding for inner lighting but horrible for exposed lighting on a prop as they are blinding. But for a basic assembly in hand, you just need replace the LED's to alter the color. Again ive done this for many years on projects where time or budget doesnt allow a custom set up. For example, it costs more than a dollar to ship something.

    Looks like these guys got you covered though.
     
  16. stromo

    stromo Well-Known Member

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    To be honest, I completely agree with robstyle. It's a much simpler solution.
     
  17. MrSinistar

    MrSinistar Well-Known Member

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    Awesome, I'll go ahead and look out for those flashlights. Thanks again for all your help, guys!
     

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