Quick LED question

[soul40k]

I just got new Blue and white LED's, and i want to test a fwe out, I figured out which connection is the +5v on the powersupply cable, and am just wondering how big of a resistor if any i need when hooking the it into the jack.

Also, is there any other way of doing this that may be betteR? Like splicing into a fan +5v and GND conenction that connects to the motherboard?

Ty.

 

[soul40k]

Maybe im stupid or just not doing this right, but regardless of what i try with a battery i get no response, even hooking up my meter directly to the battery, I get nothing.

Also, I dont remember what the guy said in terms of the volt rating on them.

 

[soul40k]

My 1.5V batteries probably arent enough to power it, they are supposed to be pretty bright LED's (3 bucks for one CND).

 

[soul40k]

Jebus crist.. I didnt even think of putting two together.. what a concept. BRB

 

[soul40k]

God I wish I had more hands..

Umm yea, 3v didnt work, so im going to try 3 connected.

 

[soul40k]

DAmmit, i couldnt get 3 connected to spark it either..

 

[Pain]

Is this a discrete LED, or is it some kit for using in computers?

 

[soul40k]

I just picked them up at an electronic store, im trying them out, using a digital output volt reader and its showing nothing, but if i try older diodes, they show them working.

 

[soul40k]

Found out problem, got it to work with just about 6v's, so that probably means 5v's.

 

[Onus]

Typical LED voltages are 2.2v-2.8v. The ones that take 6v have resistors already built-in.
Note that the "D" in L.E.D. stands for "Diode." These devices are sensitive to polarity. Two "AA" batteries should run one, but you can add all you want if the polarity is wrong until you burn your hand when you smoke it. Plugging one in to a 5V molex will likely smoke it either way from current overload unless you put a 5K-10K ohm resistor in series with it.
On a typical LED, the cathode (- side) is indicated by a flattening of the case.

 

[soul40k]

Typical LED voltages are 2.2v-2.8v. The ones that take 6v have resistors already built-in.
Note that the "D" in L.E.D. stands for "Diode." These devices are sensitive to polarity. Two "AA" batteries should run one, but you can add all you want if the polarity is wrong until you burn your hand when you smoke it. Plugging one in to a 5V molex will likely smoke it either way from current overload unless you put a 5K-10K ohm resistor in series with it.
On a typical LED, the cathode (- side) is indicated by a flattening of the case.

Lol damn, I wish I read yours before plugging it in.. Illt ry a second one with a resistor on it lol

 

[Pain]

1k should be plenty, even 500 ohm. I would guess that most LED's will handle 10ma, so 5v at 1k is 5ma. If you're talking about the extra bright LED's, they'll probably handle more current.

As always, check the specs of the devices first though.

 

[kg4icg]

LED stands for Light Emitting Diode, The only difference between a LED and a Diode is that LEDs' light up. now that being aside. All diodes are polarity sensitive. If your multimeter has a diode mode, you can check them that way.

R Collins

 

[soul40k]

Thanks everyone, I got it to work. Just a simple thing too. Makes me feel very slow lol

 

[ivoryjohn]

Kind of off subject but i just thought i would relate this story.

When i was about 10 years old my sister and i where in my room playing with my Legos. Well i had an LED from an old toy mixed in with the Legos and my sister got the bright idea to try and light it. So she sticks it in the wall socket. Well needless to say the damb thing blew up and took the cuircut breaker with it. Had to be the brightest flash i've ever seen.

:lol: :lol: :lol:

That reminds me of when I was bread boarding some audio circuits. I was trying out a variety of opamps, all 8 pin dips with the same pin out, and inadvertently inserted one backwards. Boy was I surprised when it instantly popped and bounced off the ceiling. It was neatly sheared into two halves too.

Moral of the story: DC electronics are DC for a reason, they don't go both ways.

 

[soul40k]

Well, just an update, I got it connected to a previous fan connector, applied it to the mother board, and it worked no problem, so, does this mean that I can splice it into a current fan conection witht he fan still attached, throw on a resistor, and still light up that LED?

I think this would work because someone said that the fans don't use the +5 volt anyways.

 

[Pain]

If you're talking about a molex connector, yes. If you're talking about a fan connector on the MB, there is no 5v on it.

If the LED has worked without a resistor already, then it has one built in. If you connected it to the power without a resistor to test it, then it would likely already have been distroyed.

 

[vulefu]

If you're talking about a molex connector, yes. If you're talking about a fan connector on the MB, there is no 5v on it.

If the LED has worked without a resistor already, then it has one built in. If you connected it to the power without a resistor to test it, then it would likely already have been distroyed.

yeah