Post-Text Exercises

IV. Find the word with the similar meaning according to the idea of text 6a.

1. amplifier intensifier; forcer; promoter; reducer

2. to conduct to pass; to build; to carry out; to lead

3. configuration device; system; form; equipment

4. extent tension; degree; step; state

5. potential voltage; effort; combustion; power

6. apparent obvious; normal; industrial; accurate

7. solution conclusion; appearance; answer; way out

8. to operate to go; to act; to require; to reverse

9. gain wave; effort; resource; amplification

10. arrangement transformed; unlimited; organized; reinforced

V. Complete the following. Use the words in the box to help you.

pick up, cartridge, transistor, pre-amplifier, operating point, power amplifier

Components of an amplifier system	Function
…………………………	produces an electric signal
…………………………	amplifies the small signal from the cartridge
…………………………	fulfils the high-power amplification
…………………………	rectifies the input signal
…………………………	ensures the change of the temperature

VI. Read and translate word combinations consisting of two or more components. See model. Read and translate the sentences from the text containing these word combinations.

Model: energy usage – использование энергии

power amplifier, transistor action, high-power amplifier, high-power amplification, fault conditions, characteristic curve

VII. Answer the following questions:

1. What does the amplifier consist of?

2. What parts of the signal cause the transistor to conduct?

3. What are the functions of its parts?

4. What makes the input signal sound terrible? What is the solution to this problem?

5. Why is it impossible to specify the gain of a transistor very accurately?

6. What is needed for compensation for variations in gain of the transistor?

7. How do resistors work?

8. What does the term ‘feedback’ mean?

9. What feedback is used in this case? Why is it used here?

VIII. Match the English words in column A to their Russian equivalents in column B:

A	B
pick-up cartridge speaker preamplifier terminal forward-biased rectify linear base-emitter excursion leakage ambient feedback counteract network drive	протекание, течь контур обратной связи привод, передача звукосниматель, датчик зажим, клемма схема, цепь излучатель громкоговоритель выпрямлять линейный уравновешивать, нейтрализовать сдвиг, полюс окружающий предварительный усилитель смещенный в прямом направлении

IX. Below are some figures you know from your science classes. In groups, look at them carefully and match figures with their descriptions.

Figure 1	A. Open-loop test circuit. For this circuit the connections are labeled according to pin numbering conventions. Remember this for all subsequent circuits. To find the pin allocations for other chips that you might use, the company data sheets must be consulted!
Figure 2	B. Non-inverting amplifier
Figure 3	C. An op-amp as a follower
Figure 4	D. An alternative current to voltage converter
Figure 5	E. Summing Amplifier
Figure 6	F. Inverting amplifier. The power connections are now implied.
Figure 6a	G. Integrator circuit
Figure 7	H. How the DIP goes into the breadboard
Figure 8	I. Current to voltage converter

X. Now that the functions of the main components of an amplifier are formed try to develop the basic concept of the device: a smaller current is used to modify a large current. Work in pairs to exchange your ideas.

Grammar Exercises (Word Order in a Simple Sentence. Negative Simple Sentence. Word Order in Interrogative Sentences. See APPENDIX, GR. REF., p. 111-114)

XI. Make up interrogative sentences.

1. A parallel circuit has the main line and parallel branches.

2. The circuit consists of a voltage source, a resistor and a conductor.

3. Switchboard is an assemblage of switches.

4. The capacity of a capacitor is measured in farrads.

5. The sun radiates to our planet great amounts of energy.

6. Test blocks are mounted on the front panel.

XII. Make up special questions to each member of the sentence.

1. Resistors consist of silicon sheet-steel or of special cast iron elements.

2. Many types of oscillator circuits are used nowadays.

3. The experiment was repeated many times.

4. The value of the output depends on the electrolyte of a cell.

5. Aluminium is used in common practice for transmission lines.

XIII. Read the sentences and correct them if the word order is wrong.

1. The Sun our greatest is energy source.

2. The students in the laboratory observed this phenomenon.

3. For peaceful purposes must be atomic energy used.

4. Electric arc is used in electric lamps.

5. A transformer is used energy to transfer.

6. Two diodes in a full-wave rectifier are used.

7. Conductors without a relay with a large cross-section would have to be brought to the motor.

8. Both solid and gaseous insulators are in use highly.

9. There are different types of fuses in use nowadays.

XIV. Translate the following sentences into English paying atten-tion to the word order.

1. Эта статья описывает эксперимент, связанный с электричеством.

2. Главными частями конденсатора являются металлические пласти-ны и изоляторы.

3. Проводники используются для соединения элементов цепи.

4. Существуют два распространенных способа соединения элемен-тов: или параллельно или последовательно.

5. Как результат изменения температуры и влажности, может меняться величина и характеристики некоторых компонентов.

XV. Read TEXT 6 B. Find the answers in the text to the following questions:

1. What is a diode?

2. What’s the main function of a diode?

3. How can one create a diode?

4. What are the uses of a diode?

5. What types of diodes can be distinguished according to the direction of the voltage?

6. Why is it important to choose the diodes?

TEXT 6 B. Diodes

A diode is a semiconductor device which allows current to flow through it in only one direction. So, what does a diode consist of that lets it operate by this general principle that the current is allowed to flow in one direction but not the other? Let’s consider the process of creating a typical P-N junction diode. When you put N-type and P-type silicon together as shown in this diagram, you get a very interesting phenomenon that gives a diode its unique properties.

Even though N-type silicon by itself is a conductor, and P-type silicon by itself is also a conductor, the combination shown in the diagram doesn’t conduct any electricity. The negative electrons in the N-type silicon are attracts to the positive terminal of the battery. The positive holes in the P-type silicon are attracted to the negative terminal of the battery. No current flows across the junction because the holes and the electrons one each moving in the wrong direction.

.

If you slip the battery around, the diode conducts electricity just fine. The free electrons in the N-type silicon are repelled by the negative terminal of the battery. The holes in the P-type silicon are repelled by the positive terminal. At the function between the N-type and P-type silicon, holes and free electrons meet. The electrons fill the holes. Those holes and free electrons cease to exist, and new holes and electrons spring up to take their place.

The effect is that current flows through the junction. A device that blocks the current in one direction while letting the current flow in another direction is called a diode.

Diodes can be used in a number of ways, for example:

– a diode can be used as a rectifier that converts AC (Alternating Current)

to DC (Direct Current) for a supply device;

– diodes can be used to separate the signal from radio frequencies;

– diodes can be used as an on/off switch that controls current.

When a small voltage is applied to the diode in a forward direction, current flows easily. Because the diode has a certain amount of resistance, the voltage will drop slightly as the current flows through the diode. When voltage is applied in the reverse direction through a diode, the diode will have a great resistance to the current flow. Different diodes have different characteristics when reversed-biased. This diode should be selected depending on how it’ll be used in the circuit.

The limiting voltages and currents permissible must be considered on a case by case basis. For example, when using diodes for rectification, part of the time they will be required to withstand a reverse voltage. If the diodes are not carefully, they will break down.