In the 20's battery sets were operated from a series of batteries, all required "A" batteries (tube filament supply,  "B" batteries (high voltage or plate supply) and some required "C" batteries (bias supply).

Most used a 6 volt car battery for the "A" supply, some sets (especially so called portables) used low filament drain tubes that would work from 1.5 volt dry cell batteries.

The "B" requirements varied from 22.5 volts to 135 volts with many using multiples of these.

The "C" battery was required when tubes designed for more power in the output stage were introduced, these were usually 4.5 volts and some sets required several.

Radios of the 1920s - late '30s required an external "long Wire" antenna.

The best way to operate a battery set today would be with a quality power supply designed especially for early battery radio operation, such as the ARBE III is what I use and recommend).

I am often ask if these early speakers can be operated from a modern radio or amplifier, that answer will be found on my Tech Tips page.