1. Translate into English.

1. Тут виробляються друковані плати для електронного обладнання. 2. Що керує цим перемикачем? 3. Паливний елемент (ПЕ) – це електрохімічний генератор, який забезпечує пряме перетворення хімічної енергії на електричну. 4. Нові інтегральні схеми дуже потужні. 5. Надмірне тепло, що виникає в електричних колах, може призвести до пожежі. 6. Напівпровідникові матеріали широко використовуються в електроніці. 7. В цю схему ввімкнені постійні та змінні резистори. 8. Яке призначення цієї деталі у схемі? 9. Що таке індуктивність? 10. Як працює цей пристрій? 11. Ця схема захищена плавким запобіжником. 12. Джерела електричного струму – це пристрої, що перетворюють різні види енергії на електричну енергію. 13. До хімічних джерел електричного струму належать гальванічні елементи й акумулятори. 14. Гальванічний елемент – це хімічне джерело електричного струму одноразового використання, а акумулятор – це хімічне джерело електричного струму багаторазового використання.

2. Answer the following questions.

1) What are active and passive components of an electric circuit?

2) What are the sources of electric power?

3) Which forms of energy can be transformed into electric energy?

4) What is a structure of a capacitor?

5) What is the function of a resistor?

6) What is the function of switches?

7) What is the function of a capacitor?

8) What is the function of a fuse?

9) What is a structure of a transistor?

3. Explain the following terms in your own words.

Generator Battery Electron tube

Switch Transistor Inductor

Fuse Resistor Relay

Unit 5. Transistor

Active vocabulary

arsenide base collector detector emitter incoming lattice to dope

арсенід база колектор випрямляч емітер вхідний решітка, ґратка легувати, модифікувати

quinquevalent semiconductor solid switch transistor valence integrated circuit bipolar transistor field-effect transistor, unipolar transistor

п’ятивалентний напівпровідник твердий перемикач (transfer + resis­tor) транзистор валентність інтегральна схема біполярний транзистор польовий транзистор

Reading

Read the text below.

Transistor

The transistor is a common term for a number of solid-state electronic devices which are used as active components of electronic circuit. It may be used as an amplifier, detector or switch. The transistor is capable to perform many of functions of its precursor, the vacuum tube, but it is more reliable, more flexible, and smaller in size, and it consumes less electricity. So it has almost entirely replaced the vacuum tube in electronic devices. Its application ranges from small radios to the most sophisticated space probes. The transistor revolutionized both electronic communication and computation.

The simplest transistor consists of three layers of different semiconducting materials. Common semiconductors (silicon, germani­um or gallium arsenide) have a perfectly regular diamond-cubic lattice that acts, at low temperatures, as an insulator. If small amounts of impurities with different valence structure are added to pure semicon­ductor that improves its conductivity. For example, doping tetravalent silicon with quinquevalent phosphorus gives an excess of electrons and provides a conductivity of n- (negative) type. When atoms of trivalent boron are substituted for some of the silicon atoms, each captures one electron from a neighboring silicon atom, leaving an empty space, or hole. Such holes behave as though they were freely moving particles with a positive charge, and thus they also serve to increase the silicon’s conductivity. Such doped material is of p- (positive) type. In the so-called n-p-n type transistor, the first part, called the emitter, is doped to give it an excess of negative charges; the second, the base, is doped to give it excess positive charges; and the third, the collector, is doped to give it an excess of negative charges.

The voltage applied between the emitter and collector is fixed and relatively high, while the voltage between the emitter and the base is low and variable – it is the incoming signal. When there is no base voltage, the resistance from the emitter to the collector is high, and no current flows. A small voltage across the base to the emitter, however, lowers the resistance and allows a large output current to flow from emitter to collector. The transistor thus acts as a signal amplifier.

Though transistors were clearly an improvement over the vacuum tube, they still generated a great deal of heat, which damaged the equipment’s sensitive internal parts. The quartz rock eliminated this problem. Jack Kilby, an engineer with Texas Instruments, developed the integrated circuit (IC) in 1958. The IC combined different electronic components onto a small silicon disc, which was made from quartz. Scientists later managed to fit more and more components on a single chip. As a result, instruments and machines like computers became ever smaller as more components were squeezed onto the chip.

Types of transistors. Bipolar transistors are so named because they conduct by using both majority and minority carriers. The bipolar junction transistor (BJT) is a combination of two junction diodes and is formed of either a thin layer of p-type semiconductor sandwiched between two n-type semiconductors (an n-p-n transistor), or a thin layer of n-type semiconductor sandwiched between two p-type semiconductors (a p-n-p transistor). This construction produces two p-n junctions: a base–emitter junction and a base–collector junction, separated by a thin region of semiconductor known as the base region (two junction diodes wired together without sharing an intervening semiconducting region will not make a transistor). The BJT has three terminals, corresponding to the three layers of semiconductor – an emitter, a base, and a collector. It is useful in amplifiers because the currents at the emitter and collector are controllable by a relatively small base current. Bipolar transistors can be made to conduct by exposure to light, since absorption of photons in the base region generates a photocurrent that acts as a base current; the collector current is approximately β times the photocurrent. Devices designed for this purpose have a transparent window in the package and are called phototransistors.

The field-effect transistor (FET), sometimes called a unipolar transistor, uses either electrons (in N-channel FET) or holes (in P-channel FET) for conduction. The four terminals of the FET are named source, gate, drain, and body (substrate). On most FETs, the body is connected to the source inside the package, and this will be assumed for the following description. In FETs, the drain-to-source current flows via a conducting channel that connects the source region to the drain region. The conductivity is varied by the electric field that is produced when a voltage is applied between the gate and source terminals. Unlike bipolar transistors, FETs do not inherently amplify a photocurrent. Nevertheless, there are ways to use them, especially JFETs, as light-sensitive devices, by exploiting the photocurrents in channel–gate or channel–body junctions.

Language practice.