Alright, let's see what I can get for help.. Joined just for this Here's the plan:
I've got a CM HAF XM - Mesh has been painted blue to fit with theme and getting the window panel with blue LED fans to accent the case more. Soldered around to swap out the front red LEDs for blue instead of buying a new fan and sottering that up.
I plan on getting some 3mm 20mA LEDs on the case on the outside and maybe some areas inside, making a 3D model of it to figure out placement and see where I'd like.. What I need to know is how would I get the power to the LEDs, how would I chain them up? I know I'll be using 4-pin molex or just some 4-pin molex to 3-pin fan cables I have sitting around. I have a dummy PSU so testing is no issue.
My question is, would anybody know which wires to use, how to wire it, or any other specific device/part required (other than the resistors - of which ohms, no idea - I want them dimmed so they're not too bright)? If my plan goes well in Blender, I'll be in the 36-ish LED count. I've read around about chaining 3 LEDs together to fit on the 12V rail but that's the gist of what I know. I also plan on setting them up on a rocker switch for on/off (What kind of switch would be used for this? I seem to be pointed to DPDT)
there is a long end and a short end of the LED, I think it takes like 3v to power them you might want to look that up on wikipedia, but 36 LEDs, that's going to be one bright ass case
last time i did led wiring was with a rc car of mine, black with red led underglow gosh i miss it now, to bad i used it so much that the tires wore out, cost me 75 bucks to get it just right, 75 including car and leds
^^^ that guy seems to know what the hell he's doing I'd ask him, closest thing I've done was hook up a cold cathode to my DVD players sound channels to make a visuallizer
The reason people say 3 LEDs in series on a 12 V rail is because each LED has a voltage drop of approx 3-4V and once you place 3 of them in series then the you would have dropped anywhere from 9-12v across the LEDs. Now if you put a potentiometer in series with LEDs in parallel then you can adjust the resistance to adjust the current or you could just use a regular resistor. I have worked it out for 36 LEDs with 20mA current needs then if you approximately have a 3.5V drop across the diodes then the resistance you would want is roughly 12 Ohms(make sure it is at least a 10 W wire wound resistor because you will be pumping 720 mA through it). If you have any further questions feel free to ask. Being an electrical engineer whos project is currently high power LEDs this is right up my alley.
Cheers for the info. I've got a bunch of LEDs coming so I can play around with that. In the mean time I managed to find a LED station to power them from a 4-pin molex. Just need to find the simplest means of dimming without getting loaded on resistors - since they'd all be wired into the station's pcb. Using a potentiometer or similar actually sounds like a nice idea for brightness control.. Would it work wired in through the 12v rail?
Yes the potentiometer would work fine as the voltage should stay the same but will regulate the current (ie the current will change) and therefore should theoretically regulate the brightness of the LED. Although I am not too sure what you mean by the station's pcb or the setup so I can't be completely specific without understanding the exacts of the situation.
That should work well together. A potentiometer in line with that PCB( which probably just runs the LEDs in parallel like I was suggesting) will work just fine to regulate the current controlling the brightness of the LEDs. Just remember in your setup the higher the potentiometer resistance the dimmer the LEDs will be. Looks like you are set to light that case let me know how it turns out.
Okay, I haven't read every post, but I want to throw my knowledge in the ring.
It is true that you can put a few LED's in series up to the source voltage (but never go above it). However, if you put LED's in parallel, you need a resistor for every branch! So not just the 12Ohm for 750mA someone suggested, everything would just burn out. I can explain why if you're interested.
Building a PCB would turn this into a fun project, but I don't think it's required if it's a one-time setup. Solder the required led's in series, add the appropriate resistor (give me the numbers and I'll calculate it out for you). And then connect everything up in parallel to a MOLEX (this was a good idea indeed). If you want, then you can add the dimmer to it.
Let me know if you want to know more technical details and/or numbers. But really, don't "just" use that dimming molex thing, becasue it won't work (need minimal resistors). That Mod/Smart thing is rather expensive, but probably versatile. If you get an arduino and some headers, I think you can make something cooler for a lower price.
EDIT; This diagram explains how the basic wiring goes, but don't use these risistor values, they should be calculated based on your LED's voltage drop and what current you want to achieve. (Don't use the maximum current of the LED's.) http://otherpower.com/sites/default/files/imported/images/led_diag1.JPG
Have you considered LED strips? you could really easily get a strip of 12v 3528 smd led's for under 20 bucks delivered off ebay and just hook that up. [Thats for a whole 5 meters]
Want a controller for brightness? want it to flash/strobe/blink? they'll be floating around for an extra 3 bucks, even comes with a remote, i've seen IR and wireless versions cheap.
Whats that? you dont want one colour? Great, get an RGB strip and use the controller to set any colour in the spectrum.
Want MORE light? get a 5050 SMD LED strip instead.
Why i suggest the strip?
Its easy to install, Its cheap, its simple. and you can customise it easily. For a case interior i would use strips of 3528 smds, if you dont want a strip the length of the case, cut it to 3 LED strips, which would be about 5cm long each. then solder wire to the terminals and extend the length as you like. You can power them all on a 12v rail of your PSU, battery, or their own power supply.
The short of it is i think you're overthinking a simple thing, and its better to keep it simple. Remember, you're not going to be opening your case and looking at the things, they are for ambience through a closed case.
And if you REALLY want diodes instead of SMD strips, in my experience 10mm pixels are better then 3mm pixels, and diffused are better then water clear.
I've looked into strips, but they wouldn't quite fit nicely for the desired application.These LEDs would be for that 'little extra touch' on the outside of the case - one of the reasons I wanted dimming control. That, and the alignment would become an issue with the strips. The fitting holes would be cut out in alignment with the case's design to eccentrate it. this image should give a general explanation of what I mean..
My skills in terms of pcb are down to zero. Only just starting off with all this. Though I won't be using the original desired application (I believe the LEDs with the board are 5mm from the looks of it) - I do have a handful of 3mm's coming in for next to nothing in cost to practice with all this to get a better grip of it all. I'll keep that info in mind as well. Cheers for the pointer, always glad to get more tips and info.
are you putting the LEDs inside the case with light coming out the holes in the case? or are you mounting the LEDs on the exterior within the valleys?
If strips were not an option i would use something like a diffused RGB pixel with a WS 2801 control chip per pixel, maybe drive it with an arduino so you could even throw something like lightpack at it for that little extra crazy. Wires all inside the case, pixels mounted into a drilled hole.
^^^ He is right I forgot about the thermal runaway problem that lower power LEDs have and I was treating your application as a high power LED problem. So you would need a resistor before each LED on the parallel branches. (Sorry about that)
The LEDs will be inside the case, fitted into the holes to light the outside.
I've taken the time to hunt around for some LED pixels as well as an appropriate controller and price wise it amounts to be fairly similar only with the advantages of being programmable for colouring / patterns and already in a series (I only want blue LEDs so that's not a requirement of mine).
