LED Help

Feb 20, 2006 2 Replies

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


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:

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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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