This is a demo video showing a HHO fuel cell using stainless steel tubing as the anode and cathode. This method produces quite a bit of bubbles containing the HHO gas. Round SS tubing is a little difficult to come by and to work with, but the results is great.

This demo shows the builder using an AC / DC converter to generate the 12 Volt DC current required to charge the generator. You would use the 12 Volt current from your cars alternator.