12 VDC Power Supply

[hooterville75]

Hey guys. Hope this is in the proper thread. If not please feel free to move to proper one. In regards to getting power to my Bilge Blower Motor I bought to put in my spray booth. Being that it requires 12 VDC 5 Amps to power the Motor, I got to thinking since our prior talks in regards to how I was going to power this motor.

In thinking I came up with this idea and don't why it wouldn't work. Grendels or any of you other lighting guys I'm hoping maybe you'll be able to help me out or chime in here with suggestions, concerns or ideas.

Why couldn't I get a Computer Tower Power Supply Unit 24 or 20 pin connector, clip all the wires from the ports. KEEP all the Yellow Wires which would be the 12 volt wires, KEEP all the Black Wires which would be all the negative wires and KEEP the Green Wire which would be the switch wire. CUT and ELIMINATE all the other wires.

Shrink wrap all the other wires with heat shrink wrap so they cant short anything out. Hook the Green and one ground wire to a switch for the power on/off button. Connect all the Yellow wires together including the yellow from the Bilge motor for the 12 Volt wires. Connect all the Black ground wires with the black ground wire on the bilge motor. Plug the plug into the back of the PSU and plug it into the wall. Turn the switch on and I should be in business ?

Is this possible and do you think that would work ? It would be on a 12 volt rail. Would have plenty of amps from the PSU as the smallest PC Tower PSU is 15 Amps and depending on the size of the PSU it could run all the way up to 60 Amps.

Does this seem like it work work or am I still dreaming lol ?

 

[TiM]

Computer PSUs might not switch on at their "switch" - the button on a pc goes via the motherboard and POST checked whatever the setup first...

not saying it can't work, just it might need a bit of knowhow and check with an electrical engineer for safety's sake. I know the capacitors in PSUs can be enough to end you early if you poke about not knowing what the consequences are.

If you are comfortable and SAFE adapting one then sounds like a cheap (assuming you're not buying a PSU) way to power your motor.

 

[Grendels]

I would be careful and do a search for others that have done this. I remember watching a YouTube video on the subject a while back.

As TiM said, these things can be dangerous. I would just get the power adapter that was posted in Chit Cat from amazon. Not that expensive and it is already set up to do the job you want.

http://www.amazon.com/Wagan-Amp-12V-Power-Adapter/dp/B000P7O5DG/ref=sr_1_3?ie=UTF8&qid=1349906325&sr=8-3&keywords=110+ac+to+12v+dc

You will have to do a few snips of the wire, but you will know it is safe and it won't take you as much time to do.

 

[CodeMaster]

I built a bench top power supply out of an old pc power supply, and after doing much research, I found that there is a wire in the loom (mine was grey) that is used by the motherboard to send a "Power Good" signal to the power supply that tells the supply to start supplying power through the other wires.

I faked the motherboard response by using a PIC chip to pull a pin high and connected that pin to the power good wire and everything seemed to be working fine.

Until I had it all enclosed in a a well insulated enclosure (I used MDF with vents in the appropriate places) I was very careful with using this as the 5v rails on my supply were capable of delivering 20A which is much more than the lower limit that will kill.

My enclosure is all sealed up I glued it all up rather than trying to deal with screws in MDF, so I can't post a photo of the board I designed to power the PIC and supply power to my output plugs.

My advice is like the others posted here. Be very careful, and until you know it's all working properly, I would use a power bar that is sufficiently far from the PC supply that you can turn it on without worrying about being too close to any shorts in your wiring. Not that I've ever done that. :

 

[hooterville75]

I would actually be hooking it up to a switch of its own tricking the PSU to thinking its in a computer and being turned on. I did goto youtube.com and found several videos of people doing this to create a Lab Bench Power Supply and the RC guys seem to do this alot. I have my eye on a power supply like Grendels mentioned as well. If I can get that for a reasonable price thats what Im going to do if not, Ill try this method with a ATX PSU I already have access too. Thanks for the info guys.

 

[letsgobrowns82]

There are a couple options you have. If you want to play around you can convert AC to DC using four diodes. Diodes only let electricity flow in one directions so when you connect for of them basically what happens is the AC sine wave that starts at zero, goes up to 90 then passes down across the zero axis to -90 and back to zero gets cut off on the negative half leaving you with the positive only thus creating DC. The problem with that is that its not a transformer in the sense that it does not step the voltage up or down so you would have to put resistors in the circiut to cut it down to your desired 12 volts. Thats a pain in the ass!!! You would have to play around with Ohms Law E=IxR and I'm not sure it's really worth it. Second option like Grendels said is much much easier and I would recommend it. Search around online and you can find almost any small 120AC to 12DC just make sure the amperage it puts out is enough. Remember that if your load is 5 amps it would be wise to get a transformer that is larger than that. Something 6-10 amps. Even though thats what its rated for its not going to deliver 10 amps unless your load pulls 10 amps. If you get a 5 amp and your drawing 5 amps your going to stress the transformer because its constantly pulling its max amps and its going to over heat. I hope that helps, if you have any questions just ask and I will help in any way I can.

 

[hooterville75]

I decided to convert a ATX power supply to a Lab Bench power supply using the yellow 12 volt rail and the black negative wires plenty of volts and amps . Thanks for the info Letsgobrowns.