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They were usually built by hand using circuits containing relays and vacuum tubes, and often used punch cards. -
if there was no flow of electricity, the pencil drew a straight line. When there was that flow, the pendulum swung and a zigzag was drawn on the line. -
The operation of his creature was simple: a membrane vibrated with the voice, touching a piece of iron. When the membrane and the metal piece came into contact to vibrate, an electromagnet located next to it varied its magnetic field, inducing an electric current -
It was a "portable" device weighing about ten kilograms, made from the lead sulfide crystal known as galena. It was impossible to change the dial, although the stations continued to be very scarce. -
The first televisions that can be considered commercial were of the mechanical type and were based on a rotating disk, the Nipkow disk. -
The Linus Write-Top, a very limited piece of equipment that allowed writing directly on its screen using a stylus. -
In those days an antenna covered 15 blocks around. As the user moved physically, the central transported the signal from antenna to antenna, so that the call would have continuity.