Take a 10 dollar walmart 12 volt air compressor and take it apart.

The compressor inside is very very small.

Now wire it to any of your spare batteries and a momentary switch that they sell at radio shack. And while you are there, get the big black box shown.

Alternative, walmart sells for 10 bucks a very very small compressor, no lights no guages, there is room in there to shove a battery.

You now have the "jersey modeler" of air compressors.

I've been using now for about 20 flights and I love it.

I just bought a pressure switch set at 90 psi that I'm testing an on board air compressor that always maintains pressure in my kingcat.

Very cool stuff. The compressor in side the "compressor" you get at walmart is so small you won't believe it.