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really dim blue LED ???

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gingo

Member
Joined
Oct 23, 2002
I bought a 5mm blue led from frozencpu.com. I installed it in my case and now that I finished building my system I turned it on and the blue led is REALLY dim! Its not bright at all. In order to really see the blue light you have to look at it straight on at eye level. Did I get a dud? Other poeple who have bought blue leds from frozencpu.com say they are really bright.
 

Seal

Member
Joined
Aug 14, 2002
Location
London
Yeah i havent bought one from there but sounds like its either dud or youve given it a voltage surge or something and its dead.

Also u sure u connected it to the right lines to supply the right voltage?, that helps.

seal
 

Tecumseh

Member
Joined
Feb 26, 2002
Location
Ohio
You might have one of the older generation blue LEDs. They were
not near as bright. If it were toasted you wouldn't see any light.
 
OP
gingo

gingo

Member
Joined
Oct 23, 2002
Yes, I connected it to the right headers... this thing costed $5 plus shipping............. damn
 

Yakbak

Member
Joined
Dec 31, 2001
Location
Ottawa, Canada
Maybe your mobo header isn't providing the specified voltage required for the LED.

My mobo manual says the power LED output on the mobo is 5V, but it's no where near 5V...I had to wire my blue LED straight into my 5V line.
 

nut

Registered
Joined
Oct 24, 2002
I believe Yakbak is right. Alot of other people have been having the same problem with dim light. It has to do with the required voltage. some mobo's dont have enough juice in that header, so people use resistors or i guess you can plug into the blue led straight to 5 V line. there is another thread here regarding this and explains it all. I'll try to find it for you.
 

frostmeister

Member
Joined
Jul 6, 2002
Location
Good old UK
As Tecumseh pointed out, if the LED were bust, you wouldn't see any light. There are several things that could be affecting it though.
1. Your "dropper" resistor may be to high in value.
2. You may have an LED with a voltage regulator module in it that doesn't like being plugged in where it is
3. Some other weird factor.

Although the third option isn't too helpfull, I'd need to know where it's plugged in to help more. If you're plugging it directly into the 5Volt line, what value resistor are you using? Are you using a resistor at all? or is it plugged into the HDD indicator with a resistor on the LED leads? All the above factors will influence the solution. If it is plugged into a power rail though, calculate your dropper resistor to limit current to about 20-30mA. So, for 30mA current DIRECTLY on a 5volt line, your blue LED should be droppnig somewhere in the region of 3.6 - 4Volts. This means your dropper resistor has to drop about 1.4 volts @ 30mA. 1.4 Volts divided by 30 mA = 46.666666 recurring; nearest value of 47ohms. This should be fine off of 5 volts.
 
OP
gingo

gingo

Member
Joined
Oct 23, 2002
I plugged it into the header that is labled "power led" on the bottom of my mobo. I still have the default HDD led plugged in and it is plenty bright.

How would I plug the led directley to the 5V line?

The blue led came tailed, so I dont know anything about resistors, ect.
 

frostmeister

Member
Joined
Jul 6, 2002
Location
Good old UK
Hmm - it seems like your LED has a resistor on it already. The power header on your mainboard also has a resistor. The two resistances together aren't letting enough current through. What you need to do is take the resistor off the LED and plug it back in. If you aren't too good with electronics, ask someone who knows and can make sure that there's a resistor on there to take off before you pull it apart. It should look like a cylinder shaped thing with stripes on it. It might also be covered in heat shrink sleeving. What you can do is wrap tinfoil around the resistor to short it out which will do the ame thing. Be very carefull not to let the tinfoil touch both legs of the LED though, as this could damage your mainboard if you plug in with the tinfoil shorting out the LED. You only want to short out the resistor. Good luck anyway.
 

TimDgsr

Member
Joined
Jan 17, 2002
Location
Atlanta, GA
I ordered my 3mm blue leds from www.case-mod.com they're pretty bright. 1500mcd.

they have 5mm 2200mcds as well. they're only $1.25, although ground shipping was around $5, still better than frozen's price.
 
OP
gingo

gingo

Member
Joined
Oct 23, 2002
The only problem is, I dont know how to wire my own leds... are there any tutorials on how to do it. Or places that'll do it for me?
 

ziah

Member
Joined
Oct 16, 2002
Location
northeast usa
got mine from mouser electronics. i speced out the corect voltage and just a straight swap. and they are only $1.50 - $2 a piece. and $3 for ups shipping (i got 12 each, white and blue 3mm and 5mm sizes) try them.

~z