The standard way to do this is just place DC electricity into the water using 2 metal "probes" . each probe will bubble, and the gas coming off ONE probe will be OXYGEN and the other will be HYDROGEN. However, i have heard from several sources that if you PULSE the voltage at about 620 cycles per second DC pulsed voltage... then the bubbling is much more and the amperage needed is much LOWER !!! Also, I have seen special PULSERS that are already pre-built and they sell them on EBAY for 20 or 30 bucks. I would recommend you do a search on EBAY for more information on what is available to do this..