DC supply powers the electrolysis process....
To charge the supply, use a battery or dynamo/alternator.
Read the following instructable:https://www.instructables.com/id/Bike-Generator/
Now, the circuit is complete.
I hope this instructable makes sense and has some appeal to it.
BEST OF LUCK GUYS! MAKE UR OWN VERSION SOON AND DO NOT FORGET TO SHARE IT!