Filters

B) Cover the left column and translate the Russian words back into English.

B) the coils are close together.

A) the coils are separated.

C) to prevent a short between the circuits.

B) to transfer energy.

A) to separate the circuits.

B) the secondary circuit.

A) the primary circuit.

When the coupling is tight

The function of a coupling element is

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*• a) Cover the right column and read the English words. Translate them into Russian and check your translation.

filter [Tilts] фильтр

bypass ['baipa:s] шунт

choke [tjouk] дроссель

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high-pass low-pass to oppose on the other hand choke coil bypass coil bypass condenser high-pass filter low-pass filter opposing coils opposed current

['haipa:s] ['loupais] [a'pouz]

высокопроходной низкопроходной оказывать сопротивление с другой стороны дроссельная катушка шунтовая катушка шунтирующий конденсатор фильтр верхних частот фильтр низких частот противодействующие витки противоток

-и

А. С.

** А С.

— ВС.

/?; В.С.-^

Fig. 13

This filter is used to separate direct cur­rent from alternating current. It consists of a capacitor and a choke coil. Direct current cannot flow through the capacitor since its insulators oppose the flow of direct cur­rent. Therefore, it flows through the choke coil. Its windings easily pass direct current through them. Alternating current, on the other hand, passes through the capacitor,

since it cannot easily pass through the choke coil. In this way the direct

and the alternating currents are separated.

I. A high-pass filter is used to pass high frequencies and to prevent the flow of low frequencies. It consists of a condenser and an inductance coil. The condenser passes currents of high frequencies and opposes the flow of low frequency currents. Low frequencies must be returned to the source and the inductance coil is used for a bypass.

II.A low-pass filter is used to pass low frequencies and to prevent the] flow of high frequencies. It consists of an inductance coil and a con­denser. The inductance coil passes low frequencies and opposes the flow of high frequencies. To return the high frequencies back to the source, a condenser is used for a bypass. Its capacity opposes the flow of low fre­quencies through it.

2. Complete the sentences using the correct variant.

1. A filter is used in order a) to separate d.c. from a.c.

b) to transfer energy from the primary to the secondary.

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c) to separate low frequencies from high frequencies.

2. A filter consists of a) a resistor and a transformer.

b) a choke coil and a capacitor.

c) an inductance coil and a capacitor.

3. Direct current easily passes a) through a choke coil.

b) through a capacitor.

4. Alternating current easily a) through a capacitor,
passes b) through a choke coil.

5. A low-pass filter is used a) to pass high frequencies and to prevent

the flow of low frequencies.

b) to pass low frequencies and to prevent the flow of high frequencies.

6. In a low-pass filter a) a capacitor is used as a bypass.

b) an inductance coil is used as a bypass.

7. In a high-pass filter a) an inductance coil is used as a bypass.

b) a capacitor is used as a bypass.

3. Complete these sentences using on the other hand. Follow the model.

Model: Direct current passes through the choke coil of a filter; alternating current, on the other hand, passes through the capacitor.

1. A low-pass filter is used to pass low frequencies..............

2. In a high-pass filter an inductance coil is used as a bypass....

3. A high-pass filter is used to prevent the flow of low frequencies..............

4. Alternating current passes through a capacitor...............

4. Answer the following questions:

1. What is a filter used for?

2. What does a filter consist of?

3. What is the function of a low-pass filter?

4. What is the function of a high-pass filter?

5. What is the difference between a low-pass filter and a high-pass filter?

6. What elements are used as a bypass?

7. What is the function of a choke coil?

8. What is the function of an inductance coil?

5. Draw schemes of a choke input filter and a capacity input filter. De­
scribe the schemes and the function of the filters.

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6. Read the text and answer the question that follows it.

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