This is my first instructable. This lets you use a 12volt car plug-in at home, using a 12V plug (wall wart). The initial steps are how to do it for free with stuff around the house, You can make a cleaner one from bought parts. The only thing I an unsure about is the MA (mili-amps?), I have had no trouble using my adapter on any car powered device, but I am not responsible for any problems, broken devices, electric shock, etc. (anything).

If you see any problems, I will never be too proud to make any necessary adjustments

Step 1: What You Need

You need one(1) of each of these:

1. Standard 110 standard US home outlet (don't know if it will work in other countries)
2. 12V home plug
3. Car adapter (12V)
4. Multi-tool (wire stripper, crimper, etc.)
(Optional) A car plug "cup" adapter

Step 2: What You Do

I would recommend doing all this with the "wall wart" unplugged (especially those with heart problems).

Take the wire from the 12V adapter, and cut the wire just before the end of the cord (where you plug it into something).

Next strip the covering off enough wire to connect it to the car adapter.
(Note: the end contact will always work, but only one of the side contacts works (usually)

I connected the positive to the end contact and the negative to the side contact.

NOTE: You can also buy a car adapter cup, (positive for the middle, negative for the outside contacts) for clean reuse, less resistance, and less strain on the devices. Then clean-up everything with electrical tape or shrink wrap. (the importance brought to my attention by LasVegas)
This method Extremely encouraged for those with any heart problems.

Step 3: Working!

Your homemade adapter should now work fine.

I am a novice to electricity, but love finding how things work, so created this adapter. I am not responsible for any damages or injuries you may get while trying this out.

I saw the electrical writings, and figured it would work. I searched and didn't find anything, but do not know if anyone else has listed this before.

You could use a spare car power plug for easy car device swapping.