Push-pull Amplifier

Full-wave Rectifier

In a full-wave rectifier two diodes are used. They are connected to I common load resistance. The secondary of the transformers has a centre tap to which the load is connected. Current flows through the tubes

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⁵- Complete the sentences using while. Follow the model on page 13.

1 • A half-wave rectifier contains one diode..........

2. When the upper end of the high-voltage winding is positive, current flows through the upper tube

3. During the negative half-cycle the lower tube conducts current............

6. Pair work. Put these questions to your groupmate and let him/her an­swer them.

1. How many diodes does a full-wave rectifier contain?

2. What element is the load connected to?

3. What is the direction of current in the tubes?

4. During which cycle does the plate become negative?

5. When does the lower tube conduct current?

6. When does the upper tube conduct current?

7. What is the difference between a half-wave and a full-wave rectifier?

8. What is the difference in their construction?

9. In what way does a full-wave rectifier operate?

10. In what way does a half-wave rectifier operate?

11. What are the main parts of a half-wave rectifier?

12. What are the main parts of a full-wave rectifier?

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

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

An amplifier is used to produce the output voltage greater than the mput voltage. A push-pull amplifier includes two tubes. Their control grids are connected to the opposite ends of the input transformer secon­dary winding. The centre of this winding is connected to the tube cath­odes. When maximum grid voltage is produced in one tube, minimum grid voltage is produced in the other tube. Thus, the sum of the plate

currents remains constant.

Tr,

C/?J) Uoutput

The plate currents are fed into the opposite ends of the output transformer or a choke coil. It has its centre connected through the plate current sup­ply to the cathodes. Thus direct current plate components are eliminated but alternating cur­rent components add in the cir­cuit.

3. Complete these sentences, using the correct variant:

1. An amplifier is used

to feed (fed)		питать
to include	[m'klu:d]	содержать, заключать (в себе)
to remain	[ri'mem]	оставаться
to push	lp«fl	толкать
to pull	[pul]	тянуть
push-pull		пушпул, пушпульныи
push-pull amplifier		двухтактный усилитель
push-pull circuit		двухтактная схема
push-pull transformer		пушпульныи трансформатор
feedback		обратная связь
feedback amplifier		регенеративный усилитель
feedback coil		катушка обратной связи
feeding transformer		силовой трансформатор

2. Put down the Russian for:

plate current supply_____

alternating current components
maximum grid voltage _____

transformer secondary winding

a) to separate a.c. from d.c.

b) to change the value of the input voltage.

2. The input voltage is increased a) by means of a rectifier.

b) by means of an amplifier.

3. A push-pull amplifier includes a) only one tube.

b) two tubes.

4. When maximum grid voltage a) maximum grid voltage is produced
is produced in one tube in the other tube.

b) minimum grid voltage is produced in the other tube.

5. The sum of the plate currents a) changes.

b) remains constant.

5c¹

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