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I need a floodlight for a large yard.
I want to build one using 100 white LEDs (e.g. 10x10).
The input voltage is not important for me (220v AC , 24v DC ,12v DC all are OK)
How the schematic should be?

Thanks

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Have you added up the cost of 100 white LEDs? That's going to be a lot of money. – Olin Lathrop Aug 22 '12 at 21:05
@OlinLathrop: 100 5mm LEDs will not be expensive! about 6$ in my country. – 4r1y4n Aug 22 '12 at 21:17
Not at ebay :) – Wilhelmsen Aug 22 '12 at 21:18
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You might be able to get ordinary low efficiency green or red LEDs for $.06 each, but that's not going to be true for white LEDs, especially reasonably efficient ones. Also, where is "my country"? You haven't filled in some stuff in your profile. Remember, that information is a courtesy for us, it's not for you. If you can find reasonable white LEDs for $.06 each, please post a link. – Olin Lathrop Aug 22 '12 at 21:20
@OlinLathrop: I bought 50pcs of 5mm white LEDs (alibaba.com/product-gs/317721444/…) and I paid 6$! – 4r1y4n Aug 22 '12 at 21:27
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up vote 1 down vote accepted

http://ledcalc.com/ offer the perfect calculator for your question.

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Is it possible to calculate the luminance? – 4r1y4n Aug 22 '12 at 21:20
That depends on the LEDs. They both have a luminance factor and angle of light, so the distance between each, the wattage and luminance has to be calculated after you choose the LEDs – Wilhelmsen Aug 22 '12 at 21:24
My LEDs are these: sparkinter.com/pdf/5AW4UC_8000-10000MCD.pdf – 4r1y4n Aug 22 '12 at 21:29
The mcd (milli candela, a luminence factor) is explained in japanese or something :P But I think that with a hundred of these you will have good lighting in the dark. I had 40, lit up a room VERY well – Wilhelmsen Aug 22 '12 at 21:33
;-) its mcd is 8000 to 10000 (i say from the file name) – 4r1y4n Aug 22 '12 at 21:36
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