Getting 12 volts out of an ac outlet

[rvk2]

Hey guys, newbie here...I have a project for which a small part requires a 12volt supply. I was wondering if there's some place you guys know of where I can read up on how to get a DC supply from the regular AC outlets. What I'm trying to do is make something light up, and for this I need a 12volt supply from the regular AC outlet. I've never really worked with the AC outlets, and wouldn't wanna put the house out of power without knowing what to do. So what kind of device would I need so I can just plug into the outlet and get a 12volt dc supply?

 

[d4d4ng]

Hi rvk2,

There are lots of 12V AC / DC adaptor you can use. Just visit hobbyist shop nearest to your home and ask for 12V AC / DC adaptor. It looks like this item in http://www.e-collars.com/12vdcadaptor.html

Hope this help.

Amri

 

[stevez]

Purchasing a complete power supply is likely to be the best approach. The one that Amri points out is often called a 'wall wart' - probably because of the way it apears on a wall when plugged into an outlet.

What you should do is determine, as best you can, the requirements of your power supply in terms if volts (min, max), and current (usually max is enough). Quite often an item that requires 12 VDC will run acceptably if the voltage varies by a few volts either way though some things require a tighter tolerance. The power supply current capability must be equal to or in excess of your requirements with one exception - the 12 volt wiring and the device you are powering should be protected from over-current. The supply might be capable of delivering more current than the wire or load can handle.

There are other issues that might be of concern - ripple or noise are somewhat fast variations in the voltage. Regulation describes the changes in voltage that result from changes in the load or the source. Ripple, noise and regulation are usually very important when directly powering digital/computer circuits and are addressed in the better and more expensive supplies.

You can purchase wall wart type supplies that will deliver 12 volts but be careful that you get one for DC (I have some at home that are AC) and that the connector is properly polarized. Some might be regulated and well filtered and some may not. You can also purchase low cost bench top supplies - good for about 2 amp. Wall warts seem to cover an amp or less. I just purchased some supplies that had 4 or 5 different voltages up to 12 VDC, regulated, 2 amps for $25 (US) each. They are self contained with overcurrent protection on the output.

Hope this helps.

 

[Klaus]

The way I read the question is: he wants to get a 12V DC output from a REGULAR AC outlet.

Doing that is illegal and dangerous.

You MUST use a different kind of outlet, one that's designed for and is suitable for DC. It would be polarized so the plug can only be inseted one way AND it would NOT be possible to plug regular AC plugs into this outlet.

Think about this :!:


Klaus

 

[rvk2]

Ok guys, my circuit has two terminals where I'm planning on supplying the voltage. Since I don't wanna use a battery, I'm planning on getting one of these from radioshack
https://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=980-0848

Would I be able to strip the adapter and cut the wire to use the positve and negative terminals, instead of the jack they provide? And also, would this be safe for my circuit? All I need is a 12V DC supply, and I know the AC outlet puts out 110volts here, so is there something I can do to make sure my circuit doesn't fry?

Also, thanks for the replies guys.

 

[audioguru]

The current rating of the Radio Shack power supply is only 500mA. You should determine how much current you need to "make something light up". If you are using it to light a car headlight, then the power supply will be very overloaded and it will light up. I never tried it but it might even catch on fire.