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power LED voltage

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June 10, 2004 5:45:39 AM

hey guys,

im building a new case for my compy(i like building stuff and i find myself with lots of time in the summer, so this will be a fun little project.) but i need to have at least some idea of what voltage the motherboards front panel connectors supply so i can use a proper LED for the power-on and hard drive activity indicators.

if you dont know, will an LED with a higher specified voltage still work at lower voltages? im not real into electronics, i dont know these things :-)

More about : power led voltage

a b V Motherboard
June 10, 2004 7:18:50 AM

Last I checked it was 5v. I'm guessing a 6v LED would probably work if necessary.

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June 10, 2004 7:25:52 PM

thanks, radioshack has some 5.3 volt LED's, so ill use those.
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a b V Motherboard
June 10, 2004 9:49:27 PM

That might just be what computer cases are using, simply because 5v lines often spike nearly that high.

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May 28, 2010 2:24:24 PM

What is the amperage draw or does that even matter, i guess i can figure out from an existing board powered up to check, i kinda have a completely modded HTCP in the works, steampunk style, looks like it fell out of a fallout3 game (rusty effect) tried to get vacuum tubes in the works for the hd activity indicator but decides to not go through the trouble and just have some front fan led's do the indicating XD

if you do know the amp draw however pls let me know, or if you have any advice on how to get the case fan led's to blink to the hd activity pls let me know as well, im kinda getting over zealous at this point

/head nod
a c 156 V Motherboard
May 30, 2010 1:58:08 PM

I just happened to have the side of my case off one of my computers, so I reached in with my DMM and measured between the two leads on the power LED. I measured 1.9 volts across the LED leads.

An LED will start conducting with about .7 volts across it. After that, increasing the voltage across it will increase the current through it until it glows very brightly and dies. You should limit the current through the "standard size" (I forget what it's called) to 25 ma or .025 amps by putting a resistor in series with it.

Found this calculator:
http://www.quickar.com/noqbestledcalc.htm

If you want flashing LED's, you could put together a 555 timer circuit to drive the LED's.

Google "555 timer".
May 31, 2010 11:01:08 PM

not particularily flashing but linked to the hard drive activity pin out on the mobo next to the reset/power/ blah blah

basically i am already running a entirely separate lead to the 4x leds which will be run in series with a 160 ohm resistor to be safe then i just want those led's which will be on the main fan upfront on my htcp to flash the hdd activity since im modding the crap out of my box and changed the locations of all the power on, reset buttons to the back on a slot cover. mainly i think it will look cool having white leds randomly flashing on and off on my white housing, floresant orange bladed gentle typhoon, going for a steam punk look sorta, with the outside of the case having a true rusted finish.

let me know your thoughts and i do greatly appreciate the previous advice/info given

regards

shawn

June 2, 2010 5:58:46 PM

nevermind i found exactly what i was looking for, here's the link:

HDD LED on mass mod

this was what i was going for i just didn't know how to do it, thanks for all the feedback


shawn
!