If you want to run this on batteries, note that the two A cells are installed in parallel, not in series, so voltage remains at 1-1/2 volts. You can make up a B battery by snapping together cheap 9-volt transistor radio batteries from the dollar store. Snap them together positive of one to negative of the next one and so on in a chain. They will sort of fall together in a block that way. You could use eight of them to get 72 volts which would be fine in lieu of the 67-1/2 volt battery that this calls for. You can buy a nine-volt battery snap from RS and cut it in two to get your two individual snaps to connect to your new battery block. Have fun!
