PDA

View Full Version : Home Made 12V DC Power Supply



Gerowen
06-05-2014, 12:25 AM
So like many of you, I have several old junk computers that are inop for one reason or another. I'm salvaging still working parts from them before I take them out to my rifle range and fill them full of holes and sell them for scrap.

I had the idea of taking an old ATX power supply, wiring in an on/off switch to replace the computer's power button, and removing all of the wires except one ground and one 12V positive wire. This gives me an extra 14 amp power supply to test CB/HAM radios that I'm working on, as well as other devices you would normally use in your car. Tonight I verified it is functional. Tomorrow I'm going to dig out the dremel and remove the case, and cut out spots for the switch and some red/black studs so that all of the wires will remain inside the case, and I'll have two color coded studs to attach electrical wires to instead of splicing/twisting each new device and fatiguing the wires built into the power supply.

I tested 3 different power supplies, and although all of them "said" 12V DC on the stickers, they all came in a little on the low side, but it's within safe operating range so what the heck. The longest part of the process was unsoldering all of the extra wires I didn't need from the PCB and removing them. Between making sure I was soldering the correct spot on the back side of the board and waiting for my soldering iron to melt those huge globs of solder at points where 3 and 4 wires ran together, it took about 30 minutes just to do that. I thought about cutting them off and leaving them inside, but then I figured that eventually through movement one of the hot wires inside would end up touching the outside shell of the power supply or something else important and frying the whole thing, so I removed them completely from the PCB and left only the ones I needed.

Anyway, this is the first time I've done this, and thought I'd share. The CB radio in the picture is just an extra I had laying around to test it with, and is running on the power supply in this picture.

1778

NY714
06-05-2014, 10:52 AM
Not a bad idea if on a budget. Knew a friend of mine who linked like 12-12 Volt Switching power supplies from computers to power his Sweet Sixteen, and it worked but !!! It did start at like 12 or maybe 12.5 volts but once hit the key, it dropped significantly but again it did work. Probably wasn't getting as much as he could of out of the box, but it did key-up.

Gerowen
06-07-2014, 01:36 AM
After being un-happy with the 11.8 volts I was getting, I managed to find an adjustable pot inside the power supply and managed to get it up to between 12.8 and 12.9 volts DC. When I turn on the CB radio it drops a little, and when I key down it dips to about 12.5, but no more than what my other factory made power supplies do. Just a little bit of glue to hold the switch down in place and it's g2g.

This is actually a separate power supply. In this one I decided to leave all of the wires in place and just cut them off short and wrap them in electrical tape. That allows the possibility of re-wiring it for higher or lower voltages in the future.

1779

sureshot
08-15-2014, 06:48 PM
Over here in the UK i've used them for few years now, if you lightly load the +5v rail it should bring the voltage up to just over +12v i have used them on radios and amps, mobile amps that is. Tutorial link below good one i think, another psu hack is the old xbox psu known as the brick, your get 14 amps out of one of them, if you have a scope you can load and see how clean the output is.

http://jumperone.com/2011/06/atx-power-supply-tutorial/

856
08-17-2014, 09:56 PM
http://tapatalk.imageshack.com/v2/14/08/17/59d46e0a5f2d7155b871e4aa43082ee6.jpg

100 amps @ 14.2v for 50 bucks.

http://tapatalk.imageshack.com/v2/14/08/17/6616e3a75028a2fba6275f24bbf43909.jpg

222DBFL
08-17-2014, 11:47 PM
Looks good 856! Now that's a supply! Great work there man. Wouldn't mind having something like that. What is the power supply out of if you don't mind me asking sir? It dosed look good and at 14.2v 100amps should be perfect for what I need lol. Anyway nice work and thanks for any responses. God bless.

856
08-17-2014, 11:53 PM
Looks good 856! Now that's a supply! Great work there man. Wouldn't mind having something like that. What is the power supply out of if you don't mind me asking sir? It dosed look good and at 14.2v 100amps should be perfect for what I need lol. Anyway nice work and thanks for any responses. God bless.
You can find everything you need to know right here:

http://www.mauldroppers.com/showthread.php?t=20750

I take no credit for this thing. I just put it together. The supply is a Dell 6800 server power supply and can be had on ebay for about 30 bucks.

I run a 1x4 off of it all day with no issues. You can also series two of them together.


More pics:

http://tapatalk.imageshack.com/v2/14/08/17/6623ff172ef66e77a477e228ea5a6619.jpg

http://tapatalk.imageshack.com/v2/14/08/17/e53ac16dab0251f7b6fc6cef96f9aca5.jpg

222DBFL
08-18-2014, 12:13 AM
Well it still looks good. And at that price would be well worth every penny!! I can see one of these in my future lol. If time lets me that is. Work has the front seat right now. I do have a 170amp northstar battery that is big as heck that I use, but would love to have 100 amps on tap!! Anyway thanks for the links will check this one out for sure. Have seen it floating around just didn't need it til now! Thanks 856.

856
08-18-2014, 10:38 AM
Well it still looks good. And at that price would be well worth every penny!! I can see one of these in my future lol. If time lets me that is. Work has the front seat right now. I do have a 170amp northstar battery that is big as heck that I use, but would love to have 100 amps on tap!! Anyway thanks for the links will check this one out for sure. Have seen it floating around just didn't need it til now! Thanks 856.
Honestly it's very easy. It took me longer to gather the parts than put it together. You just need the ability to follow instructions and a moderate soldering ability. The most expensive part will be a roll of # 10 wire. I used auto primary wire. Next time I will get something else like silver teflon.

222DBFL
08-18-2014, 01:22 PM
Thanks 856, time to start looking around for a dell 6800 supply. Looks like a great project to tackle. I appreciate all the replies. Have a great one and god bless.

Cwk
08-21-2015, 02:04 PM
I pulled one of two out of an old HP DL385 I had laying around. I added a small trim pot to kick the voltage up to ~13.8 and I can jump pin 9 to pin 9 on the other one to balance the load. Each one is rated @47 amps /12.15 volts so If I gang them I'll get around 90 amps.
18851886