Author Options:

I would like to power a 12v dc 10amp water pump with a 120v power source...Ideas??? Answered

What could I use to do this without actually buying a $100 converter...I have read some instructables on using a pc power supply to make a bench power supply...but that seems like more than I need...any ideas???


First let me say I know this thread is old.
A microwave oven transformer will give you all the current you want and more. Cut off the secondary winding (small wire with 2000 turns) and wind 12 turns of 16 gauge wire. Connect this to a rectifier bridge and to your motor. Check the voltage at the motor while running. You might need to remove one or 1/2 winding on the transformer. It's a good idea at that amount of current to heat sink the rectifier -- you'll want a 30 amp one, about $4 -- and put a fan on the transformer. Those are the basics. More if needed, I'm here a lot.

10 amps is more than a typical PC power supply can put out. PC power supply will shut off automatically if you try to draw too much current.

What you can always do is use more than one power supply and connect the 12v output in parallel. Current adds up that way.

Is there a reason why you want to use a PC power supply? A regular transformer (wall wart) will work fine. When I visit my local second hand store there's a rack of old transformers meant for battery chargers, telephones, modems and so on. Just find one that says 12V and at least 10 amps, it won't hurt if its greater, and you can put these in parallel too if you like.

after looking on ebay real quick...would something like this work??? but get two of them and wire them up in parallel???


kramerr, thanks for the input, I don't necessarily WANT to use a cpu power supply...but this instructable https://www.instructables.com/id/The-Ultimate-ATX-Power-Supply-Mod-With-USB-Chargin/ shows a 12v 16amp coming off of it...wasn't sure how they did that...

I haven't seen a wall wart that goes to 10amp...I'll have to keep looking, the largest one I've seen so far is 1.2amp at 12v.

A lead acid battery

That would be my first choice, but I also don't want to buy another battery and solar charger for my project (rain barrels with rv pump for better pressure).  They will be located on the backside of my garage and I can easily run ac power to them, I was assuming that it would be a cheaper alternative to getting a new battery and solar panel.

Run the mains into a transformer with 10:1 reduction, then through a rectifier bridge.  Finally, a voltage regulator (preferably switching for efficiency) as the rectified DC output will be above 12 V.

Keep in mind that most outlets are only capable of 15 A total, so you don't want to run anything else on the same outlet as this device for safety reasons.

That last bits wrong, you can pull 15A at 120 V from the supply, or 1800 Watts. Here, he only wants 120W, so there is no problem at all.

Oops, that's what I get for being a smarty-pants before my first cup of joe.

One way or another you'll need a DC supply. I suggest that you look up some surplus electronics suppliers. They often have "pulls" that are sufficient for high current drive at much lower than retail cost.


8 years ago

Hmmm, that's outside the range of a typical computer power supply, too.  Hvae you looked on eBay for a suitable power supply?