PC PSU and 12v LEDs

[Steviecuk]

I have been told I can power leds from my old PC PSU as a cost effective way of using my old unused computer. I need advice on what I can drive with them.

I want to use 10w square LEDs which require 10-12v DC and 1050mA each. I am aware that most of the outputs are 12v from the PSU. Does this mean I can only run 1 LED per output wire, or is there a way that I can run multiple of the same string.

The reason I ask is that I need to have about 6 LEDs on a string and put a time switch and a dimmer in line before them to control the set of 6.

Any help would be great. Thanks.

 

[amlu]

its not that easy with dimming high power leds.
you need a constant current power supply to power them.

you can use atx power supply, but will need something like that:
150-1500mA Buck Regulator LED Driver for 1-50W High Power LED | eBay
to regulate the current.
use a 5v pwm signal for dimming,

 

[Steviecuk]

I have been told to get a DC dimmer which should do the job apparently. http://pages.ebay.com/link/?nav=item.view&alt=web&id=400829845939

Its mainly how to get 6 LEDs running on the same string that I can't seem to figure out. Any ideas?

 

[telectrix]

6 10w LEDs total 60watts. that's 5A @ 12V.

 

[amlu]

dc dimmer will work for led strips and led modules with current limiting resistors built in.

 

[amlu]

good reading material here:
LED center » LED basics

 

[Steviecuk]

6 10w LEDs total 60watts. that's 5A @ 12V.

Thanks for your reply. However, and not questioning you, but I was told that the voltage would drop by each LED draw. Ie 6 LEDs at 12v each = 72v so would require a 72v input. But how would this work with a single 12v line?

 

[Steviecuk]

Reading up, I suppose wiring in parallel would work wouldn't it? However what's the calculation I need to do as I would need a higher current supply wouldn't it? As telectrix said, 12v 5a?

Would this be ok from the 12v PSU supply? It's rated as a total of 400w but presume that the LEDs will only draw what's needed from the available 400w. Is that right?

 

[Steviecuk]

Anyone? Is parallel an option?

 

[amlu]

anyone? me again then. no, you can not drive 10w leds directly from atx psu.
leds do not draw whats needed for them!
if connected directly they will act a short circuit on the power supply, draw whatsever available, quickly heat up and die.
you need to limit the current going to a led, for a small leds its done by resistors, for anything bigger than 3w you need
switching regulators (led drivers) .