need setup advice - LOTS of LEDs in case mod

I'm new to the forum here, and I've seen a few posts with advice on how to wire up LEDs for a case mod. However, my situation is unusual - I have about 95 LEDs of the small yellow variety (2V I think). I'm building a sandcrawler computer case, it's mostly done, but just the other day I blew out about 20 LEDs, which made me question my wiring, and I want to re-do it in a way that will guarantee they won't burn out again. So, here's what I've done, and any advice on how to improve it would be GREATLY appreciated!!

The cockpit has 20 LEDs: 4 parallel strands of 5 lights, with the 5 lights in each strand wired in series. There are 3 other strands of lights, all wired in parallel: 20, 20, and 28. I have each of these 4 main strands running off their own separate Zalman fan speed controller, acting as a resistor, and each fan controller is running off a separate fan header on the m/b. (Can you tell yet I didn't know what I was doing when I put this together?) It was one of the 20-light sections (not the cockpit) that blew out the other day; the others were all fine.

So. Given that I have five 12V fan headers on the m/b I can plug the various strands into, what would be the best way to wire these suckers so they're as bright as possible? I've already found that running more than about 30 lights, even in parallel, noticeably dims them. 28 is pushing it brightness-wise, while 20 seems about ideal. But, I'm also using rather heavy gauge copper wire, probably too thick, and I don't know if that's maybe inhibiting electrical current.

I have a lot of photos of it, if anyone wants to get a visual of the setup, just send me a private message with your email address.

Ok, first off, you must post this mod on here, it sounds awesome :D

I would highly recommend pulling the power straight off the PSU, not from the MBB headers; that might actually be where your bottleneck is (don't quote me on that though). Also, having lower gauge (ie, thicker) wire is never a bad thing; the more surface area on the wire, the more current it can transfer safely. This is why you see extension cords and jumper cables sold in such low gauges.

Another thing; it'll work better if you wire them all in series, not parallel.

thanks for the advice! I'll keep the thicker wire. I *think* I tried running them straight off the PSU before, and it didn't seem to make any difference compared to the fan headers. It could be that some of the bottleneck is the high gauge (really thin) wire originally stolen from some old case fans, I used it because I've got 7 plugs hooking up the lights/fans in the upper part of the case to the m/b, and the fan plugs are sooo much smaller than the HDD size plugs.

My concern with wiring them in series is that even with only 20 lights on a strand, that's 12V that's getting divvied up between 20 lights, which means each light gets only 0.6V. that sounds like they'd end up being very dim, especially if they're rated to run at 2V.
I made a mistake on the cockpit light description: they're all parallel, not series. I'm fine doing all 95 lights in series, I guess I can experiment with how many I can have on a strand before they start dimming too much.
I can envision a few alternatives: 6-8 lights in series, and then have however many series that turns out to be running in parallel off a 12V source? Single plug, with a resistor on there to make sure the voltage doesn't ever get too high?
Or, run say 3 or 4 of those 6-8 light series off a 12V connector: between 18 and 32 lights to a strand, each strand running on its own 12V connector w/ a resistor. Means more plugs, but maybe brighter lights...
Mainly though, based on everything I've read, I feel like I should take those Zalman fan speed controllers out of there (except for the one actually running the 5 fans) and buy real resistors - I haven't got a clue what max voltage the Zalmans are putting out, and I know I have to have at least several lights on a strand to avoid burnout.
Any other words of wisdom are appreciated, wiring that many lights is a major pain and, while i'm willing to re-do all of them if necessary...I don't ever wanna do it again on this thing :)

I'd love to post some pics of it - how do I go about doing that here?

here's another thought - assuming the LEDs are 2V each, can I run up to 6 LEDs in series off the 12V connector and just not have a resistor at all, or would that be cutting things too close? (Maybe do 8 to 10 in series off each 12V connector to make sure the voltage to each LED isn't more than 2?)

Test your 12v rails with a multimeter - you get surges and drops on any PSU when it's under load - I'd personally try 7 2v leds and see if it's bright enough. Then you can combine parallel and series to get the number you want - where you want 20, you can go with 3 parallel sets of 7 in series (ok I know thats 21 but you can always hide one lol) - that way you should be good to go.

____n_n_n_n_n_n_n______
|___n_n_n_n_n_n_n_____|
|___n_n_n_n_n_n_n_____|
| |
|_______+ -________|

Ok so it's lousy ascii art lol but it might make sense if you think of the n's as leds and pretend all the lines connect up :p

Ok I couldn't help myself - that looks terrible lol - this should make more sense heh

ok cool, totally makes sense :) and just to confirm, if I have more than 6 2V LEDs in series on a 12V connection (ignoring for the moment how many of those strands are running in parallel off the connection), I shouldn't need a resistor? I'd hate to wire up a whole bunch of LEDs at 30 or 40 cents each and promptly blow them all out. again. :P

oh, and how do I update my system specs in the "My System" thingy in the upper right of my posts? Looked at the User CP page and didn't see any options for that...thanks..

doh, you're right; I was mixing up voltage and current in my head.
slave's got it right.

The wire you're using should be fine though.

If you haven't bought the replacement LEDs yet, try sourcing them online somewhere; especially with how many you're using, you'll save quite a bit. There's a bunch of suppliers listed on our wiki: http://www.thebestcasescenario.com/m...t_Of_Suppliers

For posting pics, I would recommend making a thread for your mod in either the 'Your Mods' or 'Works in progress' sections, whichever it fits better in. To embed pictures, upload them to an online hosting service (I use photobucket) and use the 'Insert Image' button to embed them.

To update your system specs, go to 'Edit Options' from the user CP.

thanks guys, your advice along with finding some online LED wiring calculators, has really helped a lot! Be sure to check the Work in progress section - I'll post pics there today or tomorrow...

Quote:

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Originally Posted by artoodeeto

ok cool, totally makes sense :) and just to confirm, if I have more than 6 2V LEDs in series on a 12V connection (ignoring for the moment how many of those strands are running in parallel off the connection), I shouldn't need a resistor? I'd hate to wire up a whole bunch of LEDs at 30 or 40 cents each and promptly blow them all out. again. :P

oh, and how do I update my system specs in the "My System" thingy in the upper right of my posts? Looked at the User CP page and didn't see any options for that...thanks..

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No, you'll need a 1ohm resistor with that setup. Have a look at this LED Calculator:
http://led.linear1.org/led.wiz
Welcome aboard. I'm an LED freak, so I have to...
:pics:

Yeah, I actually found that LED calculator yesterday afternoon - very handy! And yes, I succumbed and uploaded photos to photobucket. This link should take you to the slideshow I set up. I also added many captions, so if you want to read them, make sure to pause the show and scroll through it with the arrow keys.

http://s597.photobucket.com/albums/t...view=slideshow

Question on the resistor - do I have to have a resistor on each series strand of lights (like the LED calculator shows), or can I get away with having a single resistor on the wire close to the plug, assuming that I do strands of equal numbers of lights? Also, does it matter if the resistor is on the positive or negative wire?
Lastly, I found that running more than 25-ish lights in parallel significantly dimmed them. Any idea, if I wired multiple series-light-strands in parallel, whether each strand will act as the single light did before (so where before I had 20 parallel lights, here I could have 20 parallel strands of 5 or 6 lights each before any significant dimming occurs)? Or would I only be able to have 20 lights total, regardless of wiring method, before dimming occurs?

Wow, impressive. Definitely an improvement over the previous version :P

OOC, what's the adapter card? Parallel? SCSI?

That looks sweet! On the resistor, you'll have to wire it up like you see on the LED calc. That'll give you the maximum brightness for each.

thanks!!
ummm...adapter card....ummm....let's see. There was a SCSI card in there for my 11x17 Epson scanner, but due to the plug not fitting through the PVC pipe pathway underneath the model after I rebuilt the underside, I've pulled the SCSI card out for now, I rarely used the scanner anyway. what's still in there is the video card...which incidentally is about 3.5" longer than what I designed the case to hold, so there was much gnashing of teeth and panicking until I successfully scooted things around to make it fit. The only other "card" in there is a PCI express sound card that came with the mobo, but I'm not sure it's visible in any of the photos, it's tucked behind the video card.

Heheh, yup, it was the SCSI card I was wondering about.

here's a couple updated photos; there's also a few more here:
http://s597.photobucket.com/albums/t...view=slideshow

another LED question - I've got 11 higher voltage LEDs and 132 2V LEDs. the 11 LEDs are individually wired in parallel; they all have built-in resistors (I *think* they're all rated for 12V, even though the lights themselves are not all the same voltage, the resistors take care of any excess).
the 132 yellow LEDs will all run off one 12V connector straight from the PSU, in strands of 6 lights + 1 ohm resistor; each of these strands is in series. All the series strands are globally wired in parallel.
What I'm wondering is, since the detachable cord from the PSU has 3 molex connectors on it, and they're wired in parallel, can I hook up the 11 higher voltage LEDs to the 2nd molex on the same cord as the 132 yellow LEDs? Or will the difference in voltage between the 2 sets cause one or the other to dim? Not sure exactly how the current/voltage things works. :)

a) a 1 ohm resistor is kind of silly. I doubt your getting parts with low tolerance's anyways, so it is in all likelihood just a piece of wire.

b) there won't be a voltage difference in the molex on the same wire, it should still give 12v

and the current/voltage thing works by V = IR ;)