Transistors

the order of the semiconductor layers, transistors are divided into

NPN and PNP types.
The electrodes of this element are called base, emitter and collector.
In the scheme, the direction of the current passing through the transistor shown by emitter arrow. The base is designed to regulate the current value in the circuit.

voltage applied to the base, but the transistor itself controls

a large current passing through the collector and emitter.
By small change in the voltage at the base you can change the strength of the current passing through the transistor over a wide range.

beginning of the development of semiconductor electronics, which eventually allowed

the creation of transistors.
In 1934, German physicist Oskar Heil patented a field-effect transistor.
In 1947, William Shockley, John Bardeen and Walter Brattain assembled the first working bipolar transistor.
December 23 is considered the day of the invention of the bipolar transistor, when the first bipolar transistor was officially presented.
It was a breakthrough in the development of integrated circuits and computers, thanks to bipolar transistors.

amplifying mode. But there are experimental developments of fully digital

DAC-based amplifiers consisting of high-power transistors which worked in key mode.
Signal generator. Transistors can operate in key or amplifying mode depending on the type of generator.
Electronic switches. Transistors operate here in key mode. Sometimes electronic keys are used to control the current in an analog capacity, such as in incandescent lamp dimmers, switching power supplies and heating appliances.

the transistors used a large number of functional elements, such

as metal contacts, housing made of different materials and other elements.
So, there are some classifications:
By the main semiconductor material
By structure
By capacity
By creation technology
By materials and construction of the case

must have four contacts - two inputs and two outputs.

But transistors basically have three contacts, that’s why one of them we assigned to a common one, so there are three types of switching on the transistor:
With a common base – it amplifies only voltage (left picture).
With a common emitter - it amplifies current and voltage (central picture).
With a common collector - it amplifies only current (right picture).

in electrical engineering. So, there are some reasons why electronic

lamps lost out:
Tiny size and light weight of transistors. That allows you to reduse the size of device.
High degree of production automation.
Low operating voltage.
They do not require preparation for work.
Low power loss compared to electronic lamps.
High mechanical strength and reliability.
Long service life.
Ability to combine multiple elements under one case.

we see some disadvantages of transistors:
To work with high voltages

we had to create a new type of transistor.
Using transistors in high power transmitters is often too expensive.
Transistors are more affected by electromagnetic pulses than electronic lamps.
Transistors are more sensitive to radiation impact.