Ferranti television receiver, c 1930s.

This demonstration model was produced by Ferranti to demonstrate how the television worked. High voltages produced by the transformer sent beams of electrons from the cathode through the anodes and onto the screen. The screen had a special coating so it fluoresced when the electrons hit. The set's variable capacitor also allowed it to receive signals from other transmitters. Its overall design shows how the earliest working televisions functioned. The first regular electronic television broadcasts began in London in 1936.