?

???? Electrical machinery Relays originated with telegraphy as electromechanical devices used to regenerate telegraph signals.The Strowger switch, Panel switch and similar ones were widely used in early automated telephone exchanges. Crossbar switches were first widely installed in the middle 20th century in Sweden, the United States and Britain, and quickly spread to the rest of the world. The electromechanical television systems of the late 19th century were less successful.

?? ?In engineering, electro mechanics combines the sciences of electromagnetism of electrical engineering and mechanics. electrical machinery in this context refers to the larger discipline which includes chemical engineering, and other related disciplines. Electrical engineering in this context also encompasses software engineering, computer engineering, and other related fields. This refers to the three major engineering disciplines of electrical engineering, mechanical engineering and civil engineering under which all other engineering disciples are classified.

???? Modern practice is common items, which in the 20th century would have used electrical machinery devices for control, today use a less expensive and more effective standard integrated microcontroller circuit containing a few million transistors and a computer program to carry out the same task through logic. Such chips have replaced most electromechanical devices, are used in most simple feedback control systems, and appear in huge numbers in everything from traffic lights to electro mechanic, though the latter case, as others where mechanical motion is involved, requires that triacs control Electro mechanic?electric actuators.
?