of a neon tube behind a mechanically spinning disk with a spiral of apertures that produced a red postage-stamp size image, enlarged to twice that size by a magnifying glass. The Baird "Televisor" (sold in 1930-1933 in the UK) is considered the first mass-produced television, selling about a thousand units.

Karl Ferdinand Braun was the first to conceive the use of a CRT as a display device in 1897. The "Braun tube" became the