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How can I connect several LEDs to 12v outlet in my PC's PSU?

I have some (about 30: red, gren, blue, white, UV etc.) LEDs laying around in my project box from a high-school project. And I want to make good use of em. so I want to make some kind of mod for my PC. I forgot the voltage of each kind. but they are all 5mm. so I am guessing they will be of very similar voltage. the problem is I have no idea about how to connect em to the available 12v outlets of my PSU. also, I am a novice with LEDs. Any help will be appreciated.

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Lftndbt8 years ago
Well the power supply is a good start. USB seems to be a lil' testy especially with numerous LeD's running. Unfortunatley the LeD's I installed within my PC, were from a 12V garden lighting kit. I believe you will need to use a resistor, yet I too am a novice and don't want to send you down the wrong path.
Padlock Lftndbt8 years ago
A standard USB port can supply 500 mA at 5 Volts. That's about 20 LEDS.
Lftndbt Padlock8 years ago
And "almost" enough to fry your comp. ;)
Padlock Lftndbt8 years ago
The only possible thing that can go wrong would be shorting it, which, with modern day PSUs, would be the equivelent of a powerloss. So, just make sure to save all documents you are working on, just to be safe.
or do this https://www.instructables.com/id/PC-Power-12-V-Current-Limiter/

computer won't power off with this but you may blast the current limiter itself in case of overload that is not completely short circuit
srk (author) 8 years ago
So, no way I can connect 10 of em to my PC? I still got 2 12v power outlets free in PSU.
Sandisk1duo srk8 years ago
yes you can connect them, but you will need to wire them in series AND in parallel

here's a link to help you choose the resistor and configuration;
http://ledcalc.com/
Padlock8 years ago
If you post the power each LED consumes, and the LED forward voltage (Or just the color) I can help you. And, refering to Lftndbt's remark, you do need to use resistors. Those resistors will vary in value, depending on the current each one consumes and the forward-voltage it is.

BTW, forward voltage is a technical term for the voltage required to light it. These vary by color, with infra red being lowest and uv being highest. Usually they all light with 5v, so 12 volts would be plenty. Below are listed some of the common values: (VDC)
Infared=1.5-1.7
Red=1.8-2.2
Orange=2.1-2.2
Green=2.1-2.4
White=3.6
Blue=3.5-3.8
LinuxH4x0r8 years ago
I use 2 in series on 5v for some basic case lighting