The Age of electronics

Electronics is the science or practice of using electricity in devices similar to transistors and radio tubes so as to get results not possible with ordinary electrical equipment. Here the electricity always flows in the copper wire or other metal conductors. When electricity passes through space as occurs within a tube or through the junction as in a transistor, such action is called electronic. Thus, if a device passes its stream of electrons through internal space or through the junction, the device is called electronic.

Without electronics there might be no radio, television, sound pictures or long-distance telephone calls. Most of these familiar equipments serve to carry or to give information; so from the very beginning communication was a main purpose of electronics.

The science of electronics now deals almost exclusively with transistors or other solid-state devices. However, until approximately 1955 vacuum tubes were the principle building blocks of electronic circuits. A vacuum tube consists of several metal electrodes of various shapes all packaged inside a glass or metal envelope which is highly evacuated. A red hot electrode (filament or cathode) emits electrons which are attracted to a positively charged electrode called the plate or anode. The electrons pass through the spaces in a metallic grid electrode on their way to the plate, and the voltage on the grid controls how many electrons reach the plate. Vacuum tubes are classified according to the number of electrodes. A diode is a valve with two electrodes. A triode has three electrodes: a filament, a plate and a control grid, and so on.

Vacuum tubes are still widely used in oscilloscopes, high power high frequency radio transmitters and in some special low noise amplifiers. As a general rule, they are inferior to modern solid-state devices in many ways. Vacuum tubes are much larger. They require considerably more electric power to operate. However, they can handle high voltages and high powers at high frequencies somewhat more easily than solid-state devices. They are also capable of withstanding temporary overloads in voltage or current which would destroy a solid-state device and then returning to normal operation.

In 1948, American scientists Bardeen, Brattain and Shockley invented the first transistor. At present transistors are widely used in amplifies, receivers, transmitters, oscillators, TV sets, measuring instruments, pulse circuits, computers and many other types of radio equipment. The invention of transistors and solid-state devices led to acceleration in the growth of electronics. Transistors are made from parts which do not wear out. They waste very little power. They require no heating to generate their free electrons. This means that equipment made with transistors is more efficient, lighter than comparable valve equipment.