OC & Modding Custom LED

blueren

blueren

Adept
Hi

There are 2 small Blue LEDs which light the front of my tempest. The left one somehow has lost its intensity and so I thought I'd change it.

Bought a couple of Blue LEDs and asked the shop keeper if I could directly give stick 'em to a 5v connection. He said that 5v would be too much and told me it'd work fine with either 1.5v or 3v. So I got myself a couple of 560 ohm resistors as suggested by him.

So I connect the negative terminal of the LED to the black terminal of the 4 pin molex and the positive terminal of the LED to the red terminal of the molex through the resistor.

When I turned it on, I get a super white color glow instead of the blue! I believe there are 2 things that could've happened.

1. The guy gave me white LEDs instead of blue
2. There is too much voltage running thru the blue LED thats emitting white

I also tried connecting the led directly to the 5 volt terminal of the molex. It was bright white and heated like hell. Too much volts I guess. They'd probably burn out.

But the funny part is that the stock LEDs that came with the case had no sort of resistance. They were directly wired to the 5v terminal. (Not the mobo pins)
So now my question is, whats the correct amount of resistance I need to add?
Are there different types of LEDs out there for higher voltages? (Specially for 5v)
And btw, my psu is VX450.
Thanks in advance
 
Most LEDs run on 3V. Anything more than 3V would kill it sooner or later. The greater the voltage, the sooner it'd die on you. :p

I'm not sure what resistance should be connected in series with the LEDs. Someone else could suggest that.
 
Gannu said:
I'm not sure what resistance should be connected in series with the LEDs. Someone else could suggest that.
Click to expand...

I had tried connecting 4LED's in series across 12v(assuming effective voltage would be 3v). They ran for about 2mins & died out.
Had tried connecting BLUE LED directly yo 12v...it was bright witish in colours and died in mere 10 secs in front of my eyes.:p
 
in most LED fans, there are 4 LEDs and looks like connected in series. i just checked the voltages to each LED, and its 3.12v to each LED.

i think you should increase the resistor ohm or add one small resistor in series to current one. Also its easier if you have a multimeter, an el~cheapo one for 200~300 bucks will do.
 
Do not connect the LED directly to a source without a proper resistance, as

excess current through it may kill it.

There are lot of LED resistance calculators online,

if you don't know how to do it yourself.

This page has help/suggestions for typical values for

diode fwd drop, current etc.

LED calculator for single LEDs
 
LEDs also react very badly to reverse voltage, so be sure of the orientation.

A blue LED glowing white is a sign of too much current or a high reverse voltage. I would use a 1K resistor to start with, and use a 1 watt resistor. It should be a decent compromise, though even 560 ohms is actually fine.

FWIW, I've directly substituted red/green LEDs on cabinets with blues and whites and they work fine - at least with all Asus mobos I've used. A tad too bright, but no burnouts yet :)
 
I had fixed LEDs for my older case with a 330 ohm resistor for each led. They worked fine. I'll try the same set up again.

I tested the LEDs with my cell phone batteries. They were indeed white and not blue. Guess the shop keeper gave me the wrong ones.
 
lol

it seems the shopkeeper has messed up. :D

btw mobile batteries are 3.7~4v usually.

You should have checked with a single AA or AAA battery.
 
1$ is almost 20 times expensive than local buy of an LED+resistor.

and no need for ny solders, just a bit of thin heatshrink wud be neat.
 
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