noob question - please help

[Abu Som3a]

i am thinking of buying led's from radioshack and using them to light my rig, they are the ones with one of the pins longer than the other, to indicate the right polarity
i already know the basic V=IR, and have some experience connecting diodes from my practical physics lessons ( I actually got an A in physics AS )
I, however have no idea how to connect the led's to the psu. the yellow wire carries +12V and i can close the connection with one of the black wires, but how can i physically do it?

thanks a lot

 

[Tesher]

try taking a look at this:
http://www.overclockersclub.com/guides/powersupplyledmod.php
he modded a psu to glow but I believe the way he connected his LEDs may be of interest to you...

 

[Abu Som3a]

i too noobish to open the psu and cut some wires. so i guess the only way is cold cathode kits, eh?

 

[Michael Daly]

i too noobish to open the psu and cut some wires. so i guess the only way is cold cathode kits, eh?

Don't give up so easily. If you're ambitious, you can put together a little regulator circuit to step down the 5V line to 3.3V and run LEDs off of that (in parallel). Here's one example found through googling "5V to 3.3V converter":
step down converter

While it specifies using a USB 5V supply, you could take the 5V from a Molex connector on the PSU.

If your PSU has SATA power connectors, you can get 3.3V directly from that (pinout here).

The challenge will be finding a connector that you can use to attach to the SATA line. You won't want to solder the LED power lines directly to the SATA power connector.

 

[Mohonri]

It's even easier than everyone here is saying. All you need is a resistor. Just take a look at this LED resistor calculator. You just enter the supply voltage (use either 5V {the red wire from your PSU} or 12V {yellow wire}) and the voltage and current rating for the diode you have, and it tells you exactly what resistor you need to use.

 

[Abu Som3a]

I already know all of that, i can do the calculations myself and i connected diodes before, using a battery

the problem is how i connect the led to the psu. im thinking about using crocodile clips or coiling a bare wire over the molex pin...

 

[Abu Som3a]

i already know that its easy and simple, but i dont know a good way to make the connection

 

[Mohonri]

Ah! I would suggest that you get a molex splitter and chop off the connectors that you don't need. That will give you easy access to the 5V, 12V and GND lines.

 

[Abu Som3a]

perfect!! this should make the job much easier
but still how can i connect the molex pin to the led?

 

[Mohonri]

You break out your soldering iron, that's how. You take the molex splitter and cut off the female connectors, since you won't use them. Once you have the right resistor, you solder one side of the resistor to the 5V line, solder the other end of the resistor to the Anode on the LED, and solder the LED's cathode to the ground line. And then you put some heatshrink or electrical tape on anything exposed so you don't get a short.

Or am I misunderstanding the question?

 _____
[12v  |
[GND  |
[GND  |-------(-)LED(+)-|
[5V___|-------resistor--|

 

[Susquehannock]

Soldering iron is always the best way to go.

Practice tinning some wires before you go for the actual mod. Plenty of great guides out there if one is inclined to search.

 

[Abu Som3a]

okay thanks
but can i simply superglue this thing instead of soldering it?

 

[Mohonri]

okay thanks
but can i simply superglue this thing instead of soldering it?

You might get away with it, but I would strongly discourage you from trying. Another alternative would be to get some sort of connector and crimp it on. You might think about getting a couple butt connectors, but for the tiny wire gauge concerned, it probably won't work. Soldering is your answer.

 

[Abu Som3a]

thanks for the reply

you guys have been extremely helpful and responsive
i will not hesitate to ask more questions, as long as i cant find the answers by searching