Instructables

I am needing an a adapter to convert 120VAC to 12VDC 8 Amps for a blower?

All the wall wart type adapters I've found don't seem to go above 3-4 Amps. And the only adapters I've seen that can handle 8 Amps are around $50. I can buy the $50 but I'm on a bit of a budget. Plus that's a lot of money in case I screw it up. I've only worked with regular wall warts before. So does anyone have any ideas or advice? (I'm going to be hitting some thrift stores today to see what I can find)

Aerospaced5 years ago
Parallel two or even three 3-4 Amp wall worts together. You will get the regulated 12VDC you want and the current.
Prfesser5 years ago
It's possible to build your own setup, if you know how to solder and can handle some very basic electronics. First you need a transformer with 12 V 8 A output (actually you can get by with a bit less than 12 V). That's the hard part, and happily http://www.surpluscenter.com has a "115:12 VAC 8 AMP TRANSFORMER" for $10.

Then you need a bridge rectifier. Surplus Center has one ($7) that is 1000 V, 35 A --- way overkill but it should be fine.

Finally you need to filter the output and possibly install a voltage regulator. May not be necessary for a blower.

An alternative would be to convert a computer ATX power supply. Some help here: http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

Good luck!
Prfesser
You lose 1.4V through the bridge rectifier...I would go 120V:15V then through the rectifier, then to a 12V regulator. With the 15V you will retain the necessary headroom for the required current drive. Unless space was an issue I would just use a computer power supply.
Doesn't the 12 vac output of the transformer give about 17 VDC when it is rectified? But you're right, an ATX power supply is probably the easiest way out. Prfesser
klee27x5 years ago
You can get that from most ATX PSUs. Or you can buy this for 20 bucks http://www.mpja.com/prodinfo.asp?number=17095+PS
Xellers5 years ago
If you need 12 volts DC at up to two dozen or so amps, then a computer power supply is perfect for you! The best part is, you can get one for free! Look up "ATX power supply mod" and there will be plenty of instructables that show you how its done. An don't worry, its not hard at all, all that you need to do is cut open the main power cable to the mother board, and wire a switch between the green and black wire. Then you can use any yellow and black wire to supply 12 VDC. Yellow is positive, and black is ground. Good luck, and feel free to ask any more questions if a problem appears.