A number of other versions of the set appeared, including some that did have a transformer, a version that operated in a motor vehicle off a 6-volt supply, using a vibrator to convert the 6V DC supply to AC which could feed a transformer with higher voltage output, and a version that operated from either dry batteries or the mains supply. The battery version commonly used tubes where the filament was heated by a single 1.5-volt dry cell and plate voltage was supplied by a (nominally) 90-volt battery.