312Views7Replies

# Can you help me wire these lights? Answered

Hi, im getting a new computer soon and the case has got me dreaming yet again. its a coolmaster stacker 830. im planning on putting blue LEDs inside so the computer glows from the two side, top and front mesh screens along with underneath and behind.

I originally thought LEDs would work but then i found these. I think this would be best for lighting things up and making everything look nice.

I first wanted to power everything via USB but i have a feeling thats out of the question with these. My plan as of now is to use my Bescor ac adapter for my video light. the adapter is 12v 500mA. would this be enough to power 6 of the led light strips i linked. also what resistiors if any should i add and how would it be best to wire them?(power branched to 6 resistors each with a LED strip or power one resistor then that branched to the LED strips)

A huge thanks to any help i get ahead of time,
Tyler K.

Tags:

The forums are retiring in 2021 and are now closed for new topics and comments.

These LED-strip lights should already have some sort of current limiting resistors, or something, in them.   The assumption on the part of the manufacturer is that you, the end user, are just going to hook them up to your car's battery, a (roughly) 12V DC, constant voltage source.   As others have pointed out, there is also a 12V rail available in your PC's power supply, capable of delivering some amount of some amount of current.

Guessing that each of those 24-blue-LED-strips is actually 8 parallel strings of 3 LEDs in series, with maybe 30 mA through each series of 3, so that the total current for one 24-blue-LED-strip is 8*30 mA = 240 mA.

If that guess is close, it means your 500 mA adapter could supply enough current for two of these strips. Since 2*240 mA = 480 mA.

If you want to run 6 of these strips, then that's 6*240 mA = 1440 mA = 1.44 A.

Of course this is all guesswork. To get a better answer, you should:

Take out your multimeter. Set it to the ammeter setting. Put it in series with the LED strip and the 12 supply. Then actually measure the current drawn by one LED strip.

Then you'll have a better idea of how much power you actually need to run one, or 2, or 6, or N of these LED light strips.

you know how many mA should the computer put out for use? would it say on the PSU? i dont have this computer or lights in my hands yet so i cant actually test stuff.

Yeah. It should say, somewhere, either a label on the side of the PSU itself, or on the data sheet from the manufacturer.

Actually any recently made PSU will probably be able to spare a few extra amperes (A) from the 12V rail. That's the impression I get from browsing through Newegg's power supply section, here:
http://www.newegg.com/Store/Category.aspx?Category=32&name=Power-Supplies

Just so that you'll recognize this specification when you see it, here is an example: (for this PSU)
+3.3V@20A, +5V@16A, +12V1@16A, +12V2@16A, -12V@0.8A, 5VSB@2.5A

To complicate matters there seems to be some new thing going on with multiple 12V rails.  The last time I bought a PSU, a few years back, it just had one 12V rail.

Anyway, it kinda looks like these new PSUs have lots of  12V power to spare.  Even with running all the fans and hard drive motors and whatnot, there will  probably still be plenty of  few amperes left over for running your LED strip lights.  What was the number I was guessing? 1.44 A? Yeah.  That's small compared to an upper limit of around 16 A.

Your computer has a really convenient plug for this -- the power supply puts out 12v DC naturally - - just hook up to the yellow and black wires of a molex connector in the case, and you're set! (Molex is the generic name for the bigger 4 wire rectangular power plugs in the computer that go to each peripheral.)

if i did this wouldn't i still need to use resistors? also im assuming the leds wouldnt have anywhere enough power pull to over hear my PSU.

Those led strips are designed for car operation, and designed for 12v input -- thus they must have resistors already built in. Any light 'strip' product I've seen has them built in. Only when working with discrete (individual) resistors and putting them together do you need to add the resistor.

You'll have to email the seller and ask how much power they consume. There are no specs for that so it's impossible to tell if the power supply would be powerful enough.