Modding a case

I think you'd be better off sticking with the 8 loops of 2 LED's each. If you wire it the way you have now with 5 loops of 4 LED's in parallel, you will need an 80ohm 5W resistor on each loop. If you went to 5 loops of 2 x 2 LED's in parallel with one resistor per loop, you can get away with using 100ohm 1/2W resistors.

Again, this is just getting more complicated. It might be more hassle to wire the first design I posted, but it is certainly the simplest solution.

(I really hope I haven't screwed the math up. Add the current draw of components in parallel, add the forward voltage of components in series.)

If you have four LED's in parallel with one current limiting resistor it will need to supply 0.12Amps and drop the voltage by 8.5V. 8.5/0.12 = 70.833ohms. 8.5*0.12 = 1.02W.

If you have two parallel loops of two LED's in series with one current limiting resistor, it needs to supply 0.06Amps and drop the voltage by 5V. 5/0.06 = 83.333ohms. 5*0.06 = 0.3W

 

If i do it your way with the 8 loops of 2 LEDS would i have to change anything if i wanted to add an extra 1-2 fans with 4 leds each? or would i just add to what i had?

 

I completely forgot you were doing this with fans. Think of each fan as a simple unit, and wire them like so (where the resistors are 180ohm 1/4W):


If you want, you can connect the positive and negative leads to a molex plug. (connect the positive lead to the terminal where the yellow wire normally is, and the negative to the black wire next to it. If you can get one of those piggyback molex connectors you commonly see on fans this would be perfect.)

As for the switch, do it like so:


Connect the positive lead in the bottom right of the diagram to a male molex plug where the yellow wire would go, and the negative lead where a black wire would go.

For the two leads I've marked with arrows, do the same but use a female molex plug so that you can plug your lights/fans in.

Depending on whether or not you can find piggyback connectors you can either do a long string of plugs and just keep adding to it as you need to, or use a lot of splitters to give you more connectors.

 

Firstly those LEDS are very over priced

if you are willing to buy LEDS in 50 packs you can get them for much cheaper and better specks

http://business.shop.ebay.com.au/items/Business-Industrial__W0QQ_catrefZ1QQ_flnZ1QQ_sacatZ12576QQ_ssnZwelltonQ5fshQQ_trksidZp3911Q2ec0Q2em282?_trksid=p3911.c0.m282
http://business.shop.ebay.com.au/items/Business-Industrial__W0QQ_catrefZ1QQ_flnZ1QQ_sacatZ12576QQ_ssnZlvehkQQ_trksidZp3911Q2ec0Q2em282?_trksid=p3911.c0.m282
http://cgi.ebay.com.au/50p-SUPER-BRIGHT-5mm-ULTRA-UV-LED-7-000mcdFREE-RESISTOR_W0QQitemZ370107518784QQcmdZViewItem?hash=item370107518784&_trksid=p3911.c0.m14&_trkparms=66%3A2|65%3A1|39%3A1|240%3A1318

these are the best stores i have used on Ebay to get leds

second those LEDs will run just fine at 3v so if you want you could run 4 in series, maybe get a 1 or 10 ohm resistor to run all 20 leds and you will be fine

if you really want i have a few spare leds i'll let go for 30c each (red and blue)

 

yeah i know they're overpriced, i've been looking at this and also the ones you've linked.

 

yeah those seem like a good deal