Electromechanics

Electromechanical devices are those that combine electrical and mechanical parts. These include electric motors, loudspeakers, some fire alarms and mechanical devices powered by them, such as calculators and adding machines; switches, solenoids, relays, crossbar switches and stepping switches.Early on, "repeaters" originated with telegraphy and were electromechanical devices used to regenerate telegraph signals. The telephony crossbar switch is an electromechanical device for switching telephone calls. They were first widely installed in the 1950s in both the United States and England, and from there quickly spread to the rest of the world. They replaced most earlier designs like the Strowger switch in larger installations. Nikola Tesla, one of the great engineers, pioneered the field of electromechanics.
Paul Nipkow proposed and patented the first electromechanical television system in 1885. Electrical typewriters developed, up to the 1980s, as "power-assisted typewriters." They contained a single electrical component in them, the motor. Where the keystroke had previously moved a typebar directly, now it engaged mechanical linkages that directed mechanical power from the motor into the typebar. This was also true of the forthcoming IBM Selectric. At Bell Labs, in the 1940s, the Bell Model V computer was developed. It was an electromechanical relay-based monster with cycle times in seconds. In 1968 Garrett Systems were invited to produce a digital computer to compete with electromechanical systems then under development for the main flight control computer in the US Navy's new F-14 Tomcat fighter.
Today, though, common items which would have used electromechanical devices for control, today use, less expensive and more effectively, a standard integrated circuit (containing a few million transistors) and write a computer program to carry out the same task through logic. Transistors have replaced almost all electromechanical devices, are used in most simple feedback control systems, and appear in huge numbers in everything from traffic lights to washing machines.