LED Power Supply Question

[Holokai]

I'm planning to build a "test" LED fixture, primarily to have something to mess with while I work on my DIY controller.

I want to double check my power supply math here:

I am planning for 4 strings of 3 LEDs each:

Philips Luxeon ES Royal Blue
3.00v @ 1000ma X 3 + LDD = 12v @ 12w

Philips Luxeon ES Neutral White
3.0v @ 1000ma x 3 + LDD = 12v @ 12w

Philips Luxeon ES Deep Red
2.2v @ 700ma x 3 + LDD = 9.6v @ 6.72w

CREE XM-L T60 (Leftovers from an abandoned project)
3.3ish v @ 3000ma(!!)
3v @ 1000ma (Where I would plan to run them) x3 + LDD = 12v @ 12w

This results in a power supply that runs a minimum of 12v and 42.72w, correct? So in reality I should shoot for a supply running 12v and 60w or so for some breathing room.

If I would also like to run the Arduino and a few accessories, that would mean more wattage, but otherwise the same correct?

Thanks!

- Chris

 

[rwb500]

how are you planning on supplying constant current to these strings? some DIY contraption? I'm not sure if I understand your question. If you just want us to double check the very simple math for total power consumption, I'm sure that is not necessary, if you are about to build a DIY constant current driver circuit.

 

[Holokai]

Hi rwb500, if I understand your question correctly, the answer is I am using 3x LDD 1000ma and one LDD 700ma. And yes, I think this question is probably quite simple but it's my first build and I wanted to be sure.

Sorry if I wasn't clear on the drivers in use!

 

[perkint]

Yep, all looks to make sense. Haven't checked the fV of the LEDs, but otther than that it seems right. And yeah, I'd go for at least 60W supply.

Tim

 

[Holokai]

Thanks Tim. Work had a couple extra Dell Laptop chargers laying around - 19.5v and 65w! Perfect!

Now I need to figure out how to find a DC connector for the plug. The research never ends.

 

[zachts]

Thanks Tim. Work had a couple extra Dell Laptop chargers laying around - 19.5v and 65w! Perfect!

Now I need to figure out how to find a DC connector for the plug. The research never ends.

Just cut the end off and splice the wires to whatever you want.......... only possible draw back is there are a few of those laptop supplies that need a feedback signal from the laptop to turn on.......only way to know is to test it out though. I've not run into the problem on any yet but some have, if only two conductors you'll be fine some though will not turn on under no load though but once connected to the array work fine.

Everything else looks fine except for running your arduino off the 19.5 volt supply, you'll need a regulator for that. But easy enough.

 

[firebladeRR1k]

In the past, the dell power supplies I have dealt with have a center pin that communicates with the laptop. The power supply provided the 19.5v no matter what but the laptop would refuse it if the supply did not communicate properly. Found out the hard way as my dog chewed through the cord. After fixing, the laptop refused to use the supply even though all was well with the voltage. The communication was not working so the laptop reported unknown power supply.