Getting power from the PSU..

gamefreak701 · Post by **gamefreak701** » Wed Dec 31, 2003 12:21 am

Alright, it says "3.3v - 5v - Gnd - Gnd - Gnd - 12v"

1. So, if I goto hook any LED that's 3.3 V upto my DC I just sawder it onto the 3.3 V pin? And if I wanted to add a 5V LED I just sawder it onto the 5V pin?

2. How much power is there to drain? Could I have like 2 5V and 1 3.3 V?

3. How exactly do I hook up the LED? Would I attach from the 3.3 Volt pin 2 wires, 1 goes into each leg on my LED? or how would that work since a LED has 2 legs and there is only 1 3.3 Volt pin?

Lol..Sorry for being so n00bish. I looked around and no tutoriels explain much of this very well..

GCGamer · Post by **GCGamer** » Sun Jan 04, 2004 9:06 pm

One Leg has to go to the 3.3 pin and the other to a GND pin.

sixteen-bit · Post by **sixteen-bit** » Sun Jan 04, 2004 9:50 pm

GCGamer wrote:One Leg has to go to the 3.3 pin and the other to a GND pin.

but you should really have a current limiting resistor in there, too; Don't want to toast the LED.

GCGamer · Post by **GCGamer** » Mon Jan 05, 2004 2:21 pm

Opps

i never added a resistor that explains y my leds would die sumtimes

gamefreak701 · Post by **gamefreak701** » Mon Jan 05, 2004 6:32 pm

I don't know what resister to get!?

What do i get..Im so new!

sixteen-bit · Post by **sixteen-bit** » Mon Jan 05, 2004 6:49 pm

Depends on the LED (if you can find it, let us know the maximum current rating of the LED) but around 200 to 300 Ohms should be fine.

gamefreak701 · Post by **gamefreak701** » Mon Jan 05, 2004 8:28 pm

If the Ohms on the LED is around 200 - 300 then I don't need a resistor?

Let's just say the LED is 3.3V and is 2,000 Mcd.

FETUS · Post by **FETUS** » Mon Jan 05, 2004 8:31 pm

sixteen-bit wrote:Depends on the LED (if you can find it, let us know the maximum current rating of the LED) but around 200 to 300 Ohms should be fine.

I use a 200 ohms on everything no led blowouts yet

MIkeyp · Post by **MIkeyp** » Thu Feb 26, 2004 4:24 pm

where do you put the resistor?

Disheveled DrFreeze · Post by **Disheveled DrFreeze** » Thu Feb 26, 2004 4:34 pm

err, you should do some math here with this thing to get it right, for instance if you were to use a 3,3v led, and put 3,3 v on it, and then you should measure the current using a multimeter, then using the formula u/i=r (u is voltage, i is current, r is resistance) you should be able to calculate the resistance

next step, you can feed a 3,3 v led with a 5v line, using a simple resistor to make sure there is only 3,3v on the led, to do this, place a resistor in series with the led, to get the right value, take a resistor with a value wich is 50% of the leds value (3,3 + 1,7 = 5 v, 1,7 * 2 = 3,4, so the R should be half as resistant as the led)

this way the led gets it 3,3v and the resistor gets limited
you can calculate the current using the formula U/R=I, for R just add the values of the led and resistor

( if you were to put a resistor and led in series on a 3,3v line, the led will get les then 3,3v and it wont be as bright as it could be on 3,3v

actually the current for both situations (3,3v without R, 5v with R)will be the same, but at 3,3v the led will shine brightest

riva16 · Post by **riva16** » Thu Feb 26, 2004 5:09 pm

Its solder, not sawder!

Drives me crazy! Can't blame you, but just looks wierd!!! Sorry...