How to Turn on a Computer Power Supply Without a Computer

Computer powers supplies are readily available and make a good 12 volt or 5 volt power supply. The only thing is when they are not connected to a computer you need a way to turn them on. It's really very simple. This is an ATX Power Supply for a typical modern computer.

Step 1: Jumping Pins

Looking down on the main ATX connector with the locking tab facing up. Jump the green and black wire, they are the pins 3 and 4 counting from the right.

I spliced and soldered in a switch to make it convenient to turn on and off.

Step 2: Video of the Process

Here is a video of the process for those who like to view it.

Comments

[Beagles]

Easy way to turn on a PS with a twenty pin plug, no need to cut into anything. Just bridge the "PS-ON" and a "Ground" a green as per my crude dwg.

[Kcb3rd]

I like this kind of projects. What are some applications would you apply it to? I would try to use it with a 'smart plug' and activate remotely. Ideas?

[EdwinM73]

You missed something important for 24 pin ATX PSU,s.

If you have a 24 pin psu you MUST connect the brown cable to an orange cable and the green to black, else if you don't connect the brown cable "voltage sense" to orange "3.3v" your psu would turn off after a second or two ! Additionally for stable and correct voltage you should also have your psu under 10% of its rated load from startup, i.e. if you have a 750watt psu you should have 75 watts of load minimum, you can just use a Panel Mount Fixed Resistor say 50 to 100 watts at 10 Ohms or less, again the psu will turn on without load but may not give the exact voltages you desire, i used a 750 watt ATX brand new psu and i get 0.12v offset with no load which for a bench power supply is ok. Hope i helped you all : )

http://uk.rs-online.com/web/p/panel-mount-fixed-resistors/0158301/

[ronanry]

2 things :

1.Shouldn't your switch be a "pushbutton" switch (the one with the spring, that make it come back in place) and not a "constant contact" one (sorry i'm hard to understand, i don't know the english term for these 2)

2. When you use a power supply, check your need and the power used ... not need to use a 650W power supply only to use the 5V ...

[AndrewW1977]

A momentary switch (push button) will not keep the power supply on, in a computer motherboard there is circuitry that keep the power supply on. The "jumper" between the two wires must be constant for the power supply to remain on. So it is necessary to have a switch on the whole time.