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LED Help

Discussion in 'Electronic Basics' started by Dillinger, Feb 20, 2006.

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  1. Dillinger

    Dillinger Guest

    Hi
    I need some advice on how to go about lighting up a picture made from
    stained glass. The frame is approximately 24" x 24" (600mm x 600mm) and the
    actual glass is 20" x 20" (500mm x 500mm)

    I want to make up a frame approx. 1" (25mm) thick to sit behind the picture
    frame. Within this I want to insert some white LED's to light the picture
    from behind.

    I need help on how many I would need, where would be the best place to
    source what I need (in the UK), what I will need (LED, resistors
    transformers?) and some ideas on mounting the LED's. Also, what sort of life
    would I get from batteries, maybe a couple of AA ones? I'd hate to have to
    start channelling walls to run power to it!

    Lots of questions but I would appreciate any help.

    TJ
     
  2. Guest

    Lets see first you will need to know the max ammount of current that
    the LED can operate then depending on that current and the voltage(ex 2
    AA = 3v) you are going to use calculate the resistance needed in the
    circuit using ohms law where R=V/I then conect the positive of the
    battery to a switch so you can turn it on and off then conectt it to
    the resistor then to the LED then to the negative of the battery
    i guess that would be all
     
  3. Bob Monsen

    Bob Monsen Guest

    If possible, I'd suggest some kind of wall adapter.

    5 white LEDs would probably be sufficient; having them shine backwards
    onto a white piece of paper might work well.

    You can get very bright LEDs from lots of places, but here is a selection:

    http://www.goldmine-elec-products.com/products.asp?dept=1207

    You can also get the wall-adapter there...

    These white LEDs usually have a 'forward voltage' of between 3 and 4
    volts. So, if you get a 5V adapter and a few 100 ohm resistors, you can
    hook them up in parallel (view with 'fixed point' font).

    5V--o----o----o----o----o
    | | | | |
    100 100 100 100 100
    | | | | |
    --- --- --- --- ---
    \ / \ / \ / \ / \ /
    --- --- --- --- ---
    | | | | |
    | | | | |
    0V--o----o----o----o----o

    This will give you (5-3.4)/100 = 16mA through the LEDs, which should
    be sufficient to make them light up nicely.

    If you just can't use a wall-adapter, 3 D cells might give you adequate
    voltage for a couple of weeks.

    --
    Regards,
    Bob Monsen

    I know not with what weapons World War III will be fought, but World
    War IV will be fought with sticks and stones.
    Albert Einstein
     
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