I use four 9 volt batteries, a switch, one resistor, one potentiometer and finally two gold plated electrodes with wrapped cotton flannel around them to make it more comfortable to my skin. I wet them with a water+bicarbonate solution. Then I add a meter to check the current running through my body.
My device gives between 0,4 mA up to 2,2 mAmps. With the switch I change the direction of the current about once every 5 minutes at least. To read more about this try the microelectricitygermkiller group at Yahoo. This device is great I can assure you. Yet they are not commercially produced because of patent rights etc....