PC power supply for my chargers

[thomanie]

Hi all,

I got an old, junked power from a Compaq PC and tried to convert it following this conversion: http://www.marcee.org/Articles/PCPowerSupply.htm

It was no good!

Seems like the C's are not really ATX compatible after all. I got it to the stage where it would output 12V with the 5V lines loaded and fan running consistently, but current was very limited. When my charger pulled about 0.5A the power would start shutting down for half a second - and making an awful clicking sound... Seems to me some montoring circuit in the power didn't get the correct input.

I ditched the Compaq one, and got another junked (and known to conform) ATX power from elsewhere. Bonus was it already had a power switch mounted in the psu case!

My 5V load is an spare Biltema (Home Depot for cars...) car brakelight mounted to the PSU side as I could not find a sandbar resistor easily.
With the 21W bulb in the brakelight there is no mistaking when the power is turned on ;) Totall cost well under USD15/EUR15 including alligator clips and power outlet sockets for the PSU front. I now have +5V and +12V, and will probably add +3V and maybe even -12V later.

In the end it turned out another success story about PC powers for modelling use :) My advice is stay away from the Compaq PSUs if you're a novice and following the conversion above :)

Will try to post a pic later...

[TMetalMan]

I am think about modding a nice 380w Antec supply that I have. It can supply 18amps on the +12v rail! My dad won't let me do any permanent modding, so it will still be capable of being a regular power supply. I am thinking of following this conversion:
http://web2.murraystate.edu/andy.batts/ps/POWERSUPPLY.HTM#TIPS

[plasticjoe]

I have built 2 so far. Take the computer power supply out of the computer, leave all the plugs on it and even the on/off switch ( you can use that as an on off switch on the powersupply later )
Take a Hard Drive or something that uses the computer's power ( floppy drive, cd, HD ) just to give it enough draw to kick on, use your voltmeter and test which leads are +12 and -12 and +5 and -5 and keep the +'s aside as many as you want to have, and put the - voltage leads aside also.
Unplug the power supply and take the cover off, remove all the - voltage leads and leave a black ( ground wire ) for every power lead you need. Leave one 5 volt lead and a ground for your load lead.Clip off the un needed leads off flush to the board,so they won't touch one another and then thread all the leads you are keeping out of the cover. Take a 10 watt/ 10 Ohm ceramic resistor solder the 5 volt lead and ground to each end and zip tie it to the side of the power supply, being sure they don't touch the power supply. It will get warm to the touch that's about it, but gives it enough of a load to kick on. Then devise a way to make power posts negative and positive ( I used cutoff Teflon from work and nuts and screws to make the posts and the Teflon is a great insulator.
I have used mine with supervision I may add, and it works great, as with anything "home built" and 110V and plugged into the house/garage, I keep a sharp eye on it, just to be safe. also when testing it, I made sure that it was plugged into a breakered powerstrip. As extra caution, I use it with a powerstrip also. Hope this helps, I think I covered most of the bases on this.
You can get the resistors at radio shack in a 2 pack for about $2.00