Solid state electronics: from the electric egg to the circuits

From the electric egg to solid state electronics . The first attempt to create an electric lamp dates back to 1813; it was Sir Humphry Davy, a chemist and physicist from the United Kingdom, who tried to create it with his knowledge. Davy used two sticks of charcoal , between which to strike an electric arc. The two sticks were enclosed in a glass vial in order to avoid the rapid combustion of the same. The air contained in the ampoule was rarefied with the use of another machine, and everything was powered by a series of batteries. Later it will be Foucault who will replace the charcoal sticks.

Swan, then Edison: solid state electronics

It took several inventions to get to solid state electronics. The invention of the thermionic valve is unsuspectedly linked to the design of light bulbs. Wilson Swsan, English chemist and inventor, patented a first type in 1878. This first bulb was built from a thick carbon filament which, when heated, emitted light and gas. Swan's creation immediately presented two defects: the first was the easy breaking of the filament; the second was a deposit of dark gas which in a short time covered the whole ampoule making it unusable.

Royalty free light bulb image

The invention was then improved by Thomas Edison, an American inventor and entrepreneur, who first reduced the thickness of the filament and then added a metal wire inside the bulb , thus attempting to preserve the transparency of the glass. He thought that the gas particles were electrically charged and emitted from the filament. Edison verified that the negatively charged gas particles detached from the filament were attracted to the barrier connected to the positive instead of depositing on the bulb.

The triode

The construction of the first valve was the work of Lee De Forest , American scientist and inventor, who, in collaboration with Western Electric, had created a wireless telegraph receiver. In 1906, starting from Fleming's diode, he created the vacuum tube, a tube in which a third metal element, in the shape of a grid, was interposed between the anode and the cathode. This grid allowed the control of the electronic flow thus determining an amplifier effect of a small signal applied to it. Thus was born the Audion .

In 1914 the AT&T. , a telephone company, used De Forest's amplifier as a repeater on its long-distance lines . Thus began with the first three-element thermionic tube, the triode , that is the first device capable of guaranteeing the amplification of a signal the long way towards solid-state electronics.

solid state electronics

Solid state electronics: amplifiers

Today amps are mostly built with solid state electronics , and are commonly used in electronic devices, both analog and digital. Among the electronic systems that contain amplifiers are: cell phones, audio systems, DVD players, GPS. The purpose of the amplifiers contained in these devices is to amplify small-amplitude analog signals into signals suitable for analog-digital conversion by appropriately modifying their amplitude.

The United States was the first to implement semiconductor circuits in the military field, thanks to the many advantages offered by these circuits: small size, high reliability, low consumption. While in the rest of the world there was still an intense use of old tube technologies. But innovations do not always immediately turn out to be up to expectations or the technologies that preceded them.

solid state electronics

In fact, it is said that in the 1960s, during war exercises in a site used for atomic tests and therefore extremely radioactive, the American Air Force observed that its fighter planes, which already possessed all the avionics based on semiconductors, the Transistors , they had proved vulnerable and inferior to the Soviet ones . The Soviet fighters, with the avionics still all made up of circuits based on the old technology of thermionic valves. This technology in those years was beginning to give the baton to solid-state electronics, but it turned out to be much more reliable and much less sensitive to radiation, unlike the American one.

Radiation proof circuits

In those same years, companies specialized in the production of integrated circuits resistant to radiation "Radiation-hardned electronics" were born. In fact, many years passed before the first germanium transistors completely replaced the tubes having big limitations. Even today, valves have not been completely abandoned, still occupying a limited niche of applications for which they work very well and better than solid-state electronic technology.

The main purpose of the thermionic tubes was to manage the electrons emitted by a red-hot wire and which circulating free in the vacuum create the amplifier effect, while in the transistor technology the electrons move in a solid body.

The article Solid state electronics: from the electric egg to the circuits was written on: Tech CuE | Close-up Engineering .