LEDS (need help with reistors and so on)

[ThePunkGeek]

ok i have 6 ultrabight red leds and there just the leds. could anyone tells me in short what i need to get so i could put 12v off them from my psu. I don't know alot about this stuff but i can solder so thanks for the help

[h0mersimps0n]

whoa, wouldn't connect to the 12v line. You'll probably have to add some resistors just to work off the 5v line.

there is a really nice resistor calculator website out there, I can find it if you'd like, I wish they'd sticky the freekin site somewhere

[JimmyG]

R = Volts/ Amps = (12-1.5)/.05 = 210 ohms

This assumes your 12 volt line is exactly 12 volts, the voltage drop across the LED is 1.5 Volts, and the current draw for full brightness is 50 milliamps or .05 amps.

You can experiment with resistors from 200 to 300 ohms and pick the one that gives you the best brightness. If the specs for your LED are different than my assumptions, just substitute those values into the formula above and recalculate.

[Tbird man]

my green laser LEDS (10,000mcd) needed a 470ohm resistor to work off the 12v, or was that the 5v. whatever it is not universal. where did you get your LEDs?

[nixie]

I'm using 220 ohm resistors for 3.5V led's from the 5v line.

I think that around 3 to 3.5v is normal for leds. Dontt worry if you can't find the exact resistance required as the leds can cope with alittle more juice with out problems (ie mine will take a max of 4v with blowing up).

If you post the led specs (voltage and current ratings, should be on the package) we can tell you what you need. You may have to buy a minimum of 50 resistors though as they are so cheep (I payed £1.5 for 50).

[Starfoxer]

send cybermouse 45 a PM

he knows

he helped me with mine.

umm cant explain it very well

i soldered i think a 45OHM resistor to the long part

then copper wire to it

and copper wire to the short part


then the resistor part runs to the yellow

and the wire short part runs to the black


Cyber's


http://www.theforumisdown.com/uploadfiles/0702/LEDsetup.jpg

Mine

http://www.theforumisdown.com/uploadfiles/0702/doneled.JPG

[Ziggey]

LED Calculator (http://www.bit-tech.net/article/68/)

[ThePunkGeek]

ok i don't want to experimient i wanna know how to use these is all what do i need what do i do bottom line thanks

[Ziggey]

What do you do?
Umm wire them to your PSU. If it must be off of the 12v line I guess you can run a couple sets of them in series to x out the resisters all together. Or wire them seperate to the same 12v lead, and add a resister. Use the math formula provided to figure out what resister.
You need some good wire, maybe 18 gauge or so. Some heat shrink, and of course the solder.

You could use them to light up your case. Light up certain parts of your case. Make some sort of led bezel light show. Ummmmm the possibilities are endless.

Hope that helped more.

[fluffycow]

it would be cool if you could find (or make) a big string of those ultra bright leds and light up the whole case, those things can last 20 years when left on 24/7 if you don't overvoltage em.

[Mpegger]

LED 101 Class (http://misty.com/people/don//ledd.html) starting as soon as you click.:D

It'l give you info on how to determine the proper value of resistors for your leds.

[ThePunkGeek]

i read that and still confused.
my 12v on my psu is around 12.20-12.30
they are ultra bright red leds (5mm)

i take it from that article that 1.9v is safe limit for the my leds.

but from there i am lost. thanks for the help

[ThePunkGeek]

how do i determine the milliamps i must use?

[ThePunkGeek]

if its 10ma i would need a 1200ohm resister would this work?

[ThePunkGeek]

Originally posted by ThePunkGeek
if its 10ma i would need a 1200ohm resister would this work?

umm or 50mA and use a 220ohm resistor?

[JimmyG]

Originally posted by JimmyG
R = Volts/ Amps = (12-1.5)/.05 = 210 ohms

This assumes your 12 volt line is exactly 12 volts, the voltage drop across the LED is 1.5 Volts, and the current draw for full brightness is 50 milliamps or .05 amps.

You can experiment with resistors from 200 to 300 ohms and pick the one that gives you the best brightness. If the specs for your LED are different than my assumptions, just substitute those values into the formula above and recalculate.

You're trying to get too technical. Just try some resistors between 200 and 400 ohms and pick the one that gives you the brightness you want. Resistors are cheap. It ain't rocket science.

P.S. Start with the largest value resistor and work your way down.

[Lusankya]

break apart some cheap toy that lights up and use a 9v battery to practice on.... better then practicing with a REAL power source and a hell of alot safer

I'm sure as hell gonna test with a spare mouse and a 9v before I try plugging it into the real power

[jadams]

Originally posted by ThePunkGeek
how do i determine the milliamps i must use?

Do you have the package they came in? Is should tell you the mA on there, as well as the voltage. If you don't have the package then...I don't know :)

Here is a basic guide to help you decide what resistors you need: http://www.metku.net/index.html?sect=view&n=1&path=mods/sahkooppi/index_eng

Good Luck!