I would like to use a ATX power supply for the raspberry pi

[fig]

I'll be connecting parts from a desktop pc to the raspberry pi which is why I've decided to use a ATX power supply unit. I found this thread which offers a few suggestions
http://www.raspberrypi.org/phpBB3/viewt ... 0&p=391540
And the post by 'waygood' seems to be what I need to do but I'm new to circuits so I'd like confirmation before I start down this path.
Thanks

[klricks]

Yes you can use an ATX power supply. Most people use the standby line as it has 5V power at all times even with the power supply switched off.
Using the main 5V output requires the supply switched on... fan running and probably a 'dummy load' in order to fool the supply into turning on the 5V output.
Google ATX bench power supply... there are many many tutorials and step by step guides on doing this.

The other poster had more than one post not sure which you are referring too?

[fig]

Thanks for the reply
I've managed to get just the raspberry pi running of the standby wire and now I need to supply power for the peripherals. The video(linked by waygood post #4) mentions that I need a 'NPN Transistor' but which one should I buy, I have a choice of three.
Low Power LF NPN Transistor TO92h Case
Standard Bipolar NPN Power Transistors
High Power NPN Silicon Transistors
Thanks for your help
P.S. I found a couple of videos about converting the ATX PSU to a bench PSU but they involved hacking off the plugs and connectors which I prefer not to do.

[klricks]

The standby power 2.5A should be enough for the RPi and most other peripherals What are you trying to power?

Some transistor part numbers are listed in replies to the video.

I am not sure the purpose of having a GPIO on the RPi turn on the main PS with the transistor circuit? Why bother?

If you just want to turn on the main 5V (and 12V) output you don't need the transistor circuit Just a jumper the sense wire to a ground wire.

Here is more discussion:
http://www.raspberrypi.org/phpBB3/viewt ... 63&t=12987

[fig]

Thanks for the information and link, very helpful. Seems that a jumper is what I need to do but I'm a little confused. When I jumper the PowerOn(pin 16 green) to Ground(black) with an ordinary piece of cable/wire I get 5v and 12v current but not with the Sense(pin 13 brown) to Ground(black) so should I be jumping the Sense wire with something else.
What I'm thinking of doing is connecting up a HDD, DVD and a powered usb hub.

"I am not sure the purpose of having a GPIO on the RPi turn on the main PS with the transistor circuit? Why bother?" If only I had enough knowledge about this to agree or disagree, but I'm slowly getting there:)
Regards

[klricks]

Thanks for the information and link, very helpful. Seems that a jumper is what I need to do but I'm a little confused. When I jumper the PowerOn(pin 16 green) to Ground(black) with an ordinary piece of cable/wire I get 5v and 12v current but not with the Sense(pin 13 brown) to Ground(black) so should I be jumping the Sense wire with something else.
What I'm thinking of doing is connecting up a HDD, DVD and a powered usb hub.

"I am not sure the purpose of having a GPIO on the RPi turn on the main PS with the transistor circuit? Why bother?" If only I had enough knowledge about this to agree or disagree, but I'm slowly getting there:)
Regards

Sorry I used the wrong term.
What I meant was the green Power On wire to ground only. Do not connect the brown sense to anything,,,, that wire is only used by a computer motherboard.

The question is do you want the ability to turn the main power supply on or off at will using a program running on the RPi OR do you want to have the outputs always turned on using a jumper?

Some info on ATX:
http://en.wikipedia.org/wiki/ATX

[fig]

I think a jumper will do for my needs.
Thanks again for all your help