# LED Power supply



## avarax (Aug 18, 2010)

Hello all..... I have a question for you. I bought those pre-wired LEDs suggested in AllenH's video, and have yet to buy the power supply. I went a little overboard for the size of my yard (is there really such a thing?) and ended up buying 37 LEDs. My question to you all is this...should I get a few power supplies (I think the tutorial suggested 300 mA ones at 15 LEDs per supply) and wire them up like that, or do you suggest I get one bigger one and wire them ALL to one supply (I was thinking something along the lines of 600 mA and just using 30 of my lights).


Suggestions?


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## stagehand1975 (Feb 22, 2010)

A lot of people here have used a hacked computer power supply with success. You could place the power supply somewhere convienient and getsome landscape cable and run it from one end of the yard to the other. You can search here for threads about the pc power supply and led lighting tutorials.


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## goneferal (Sep 8, 2010)

I'm just using a 12 volt wall wart for about 140 LEDs. There are basically 16 strings and each string is wired in parallel.


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## corey872 (Jan 10, 2010)

Good suggestions above. Decent power supplies like this are usually everywhere, and can be had for cheap or free. ATX computer supplies, wall warts, SMPS 'bricks' which charge laptops, etc can all be used provided you use the proper resistor to make the LEDs happy.

If you do go to buy one, in either case you mention - 300mA / 15 LEDs, 600mA / 30 LEDs, you'd be running the power supply at it's maximum rating which doesn't allow for any overhead, doesn't take into account any voltage drop if you run any significant length of wire to the LEDs, and doesn't account for any power being used if you have resistors to limit current to the LEDs. 

I don't know how 'spread out' you intend this display to be, but even 5 feet of wire to each of 37 LEDs is 185 feet of wire, then if you're running red, green, and blue LEDs, those will need different voltages, so resistors will probably be used which further burn up power.

I don't know what this store is charging for power supplies, but in gereral, there isn't but a few cents worth of difference between a 300mA supply and a 3 amp (3000mA) supply. Having extra current won't hurt anything, though you would want to step down if the supply has a higher voltage. 

Personally, I'd look for a supply of at least 1.5A (1500mA). That would give you the 750mA for all your LEDs, plus a little extra for loss in wires and resistors. If you think you might have more LEDs in the future, a bigger supply now would only help more.


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## Hallowennie315 (Sep 5, 2007)

Hi Avarax. I made the same exact LEDs and I'm using this adapter:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=129-077

This is regulated so it doesn't matter how few lights you put on it because they won't burn out. Using this, you can put up to 100 spotlights on it. (you'd probably be sick of making spotlights by then...)


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