# Noob Question about Powering LEDs



## redbouche (Feb 23, 2010)

Let me start by saying that I pretty much don't know what I'm talking about, but that being said, I saw this LED on newark.com and though man that seems perfect for a small aquarium set up. It's a Bridgelux BXRA-C1202

http://www.newark.com/bridgelux/bxra...ays/dp/60R6540

1320lm output, 12.7V, 1.05A, so just under 100lm/Watt. That ain't bad. And it even has a nice peak around 450mn for plant growth. And all for about $17. So the question is, this has a minimum forward voltage of 11.8V, and I can get a 12V 1A power supply on eBay for all of $4. Can I just wire this thing straight to the power supply without worrying about regulators, or buckpucks, or limiting resistors, or any of the other various things that I don't quite understand yet. The power supply is pumping out exactly what I need correct? Or if I wanted to run 3, I could get a 12V 3A supply and run them in parrallel? I understand I will probably need a pretty massive heat sink for a 12W LED. How big are we talking about? Is this a viable option, or am I really over simplifying this? Am I dreaming to think I can have a 4000lm LED fixture for $70 plus the heat sink?


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## gwclark (May 10, 2010)

Hello redbouche,

The new HO LEDs are kind of touchy when it comes to their power requirements. You could use the supply mentioned if it is well regulated to 12v. However, in order to protect your expensive LEDs I would recommend adding a voltage and current limiting circuit to maintain exactly 11.8V and 1.05 amps. I have no experience with the eBay power supplies, but have built several dozen over the years. I am concerned about the voltage regulation on a supply that is only $4. Secondly running a power supply at 100% capacity at 100% duty cycle it will probably be rather short lived. 

Normally when running multiple LEDs they are run in series. This helps further mitigate any variation in voltage by spreading the error across multiple LEDs in the circuit.

LEDs are coming down in price everyday. I believe they are the future aquariums. I am currently designing an array for my 20 gallon long tank and its 10 gallon sump. Between the two I will be using 48 1W eBay LEDs. The power supply will provide 96 volts for the 30 LEDs in the main hood and 57.6 volts for the sump. Both supplies will be current limited to .35 amps.

Please don't let my comments dissuade you from trying this though. Please let me know if I can be of further assistance.


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## NonSequitur (Mar 25, 2010)

I would definitely suggest going with a higher quality power supply. As gwclark said, running a cheap supply at 100% output, 100% duty cycle will vastly shorten it's life, and possibly push it to behave in ways that could be harmful to your LEDs. A better option would be powering the LEDs off of the power supply suggested by the site or another quality constant current supply. It would cost more, but you'd run a much lower risk of frying your expensive LED.


That being said, I'm really curious to know how those LEDs work in real life. If you end up getting one, please let us know your impressions.


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## majstor76 (Feb 11, 2010)

For a 12W powerled i would use heat sink for processor and first couple of days would monitor temperature. Use thermal adhesive glue for glueing led to heatsink. And listen to people, use constant current driver


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## dzsenci (May 10, 2010)

hi 
i work whit LED's and i suggest if u don't want to kill it fast use the power supply that the site offers 4 u


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