I believe that if you use the +60 and -60 idea, then all you are doing is changing which plate is your anode/cathode repeatedly. What you end up with is a plate creating Hydrogen for 1/60 of a second and then Oxygen for the next 1/60 of a second. This would bounce back and forth 60 times every second (or 50 for those in Europe).
The recombining of HHO into water requires an ignition source and would be very violent. I don't see that happening by just using AC.
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Some days I get the sinking feeling that Orwell was an optimist!