I was wondering how many 3mm LED's can I run off a floppy cable? I dont know how much power LED's take, like the ones on frozenCPU. I realize you can have LED's under volted but then they arent as bright. I'd like to have them as bright as possible without having them burnout.

hey dreyco i noticed that you went from lokies hoe to clowns hoe..

But back on topic..
Im not sure but i would think you could run around 3 led's off of a standerd floppy cable.. but dont take my word.. Im not a huge fan of LED's

Quote: Originally Posted by Dreyco I was wondering how many 3mm LED's can I run off a floppy cable? I dont know how much power LED's take, like the ones on frozenCPU. I realize you can have LED's under volted but then they arent as bright. I'd like to have them as bright as possible without having them burnout.

Im not sure. I would ask Twizted. I dunno if he will check PR. Check out www.dragonmodz.net they have some leds and post in their forum im sure Twizted will see it there and help.

Off a floppy cable (36 pin ribon or whatever), or off a floppy power connector? The ribbon cable wouldnt run any LEDs i think, as for the power cable, its just a standard 12/5/G IIRC.

Sorry my mistake, I meant the 4(?) pin floppy power cable...

EDIT: nice to see you back online vaini!

It all depends on the what the led's foward voltage is rated at. In most cases its anywhere from 1.7vdc up to 3vdc with good led's that have a high mcd rating. If your wondering how many you could run off of the 12vdc line and you were running the led's in series than the math would be simple. 12VDC/foward VDC=#of Led's capable on provided load. The same equation would be used for the 5VDC line also if you are running in series. If you plan to run them in parrallel than you could run as many as you could solder on within a reasonable amount....id say no more than 7 on each wire. Also take into consideration that if you did run them in parrallel that youd have to solder in a resistor before each LED. This would bring Ohms law into play which is E=I x R......Basically Voltage= Current x Resistance. So if your wanting to figure out the Resistance needed for each LED youd take the supplied voltage and divide it by how many miliamps your LED is rated at. Sorry if this is rushed but im headed to bed. Best of luck and PM if you have anymore questions.

(^ beat me to posting first)
from the 5 volt (red) you can run one non low energy LED (basicly any modern bright LED) at full brightness.
from 12 volt (yellow wire) you can run 3.
this is because most LEDs have a forward voltage of 3.3-3.6 nominal (4.5 is usually the max)
basicy your total forward voltage has to be less or equal the the supply for full output. you then add a resistor to bring the voltage down to the what the LED needs.
to find the resistor it is (supply voltage - total forward voltage ) / forward current (supply voltage minus total forwardvoltage which is the forward voltages of all LEDs added together then take that and divide it by the forward current of the LEDs) you should run LEDs in series with a resistor or use a resistor for each LED

See, im looking on frozen CPU and i dont see what voltage they take. Anyhelp there or links to other places I can get bright green and blue LED's?

Thanks for the help guys

well it seems they answered your question dreyco..
so im just going to make a little scene with smilies..:

Mayhem And Destruction
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www.dragonmodz.net is where i get my LED's. There all super bright (high mcd rating) LED's and there damn cheap.....screw radiocrap. Also they let you know exactly what your buying including the foward voltage and so on.

So they are 3.5v so on a 12v i could hook up 2green and 2 blue and thave them a little under volted? Then maybe 2 on the 5v? Or should I think about using resistors? Also I would like to put these on my gf's lappy, but I dont know what the board voltage is? Would they still glow? (they dont need to be very bright...)

You might want to check out lsdiodes.com. They have alot of leds and they are very cheap. They also have little tutorials on how to hook up the LED's and what resistors to use. They also sell resistors there too and shipping will be pretty cheap too.