Amplifier Stages in Series

Amplifiers in use nowadays contain several stages. Sometimes their number is very great. Let us consider an amplifier including three stages. Its circuit uses three triodes connected in series. The circuit has a resistance as the plate load. A common plate voltage supply and a common grid bias are employed. The grid of each tube is insulated from the direct current component of the plate voltage by means of a capacitor. When the amplifier operates the voltage operation of the load

of one tube is applied to the grid of the next tube. The voltage variation is  transferred to the grid of the following tube through a capacitor. A change of  voltage on the first grid circuit results in an amplified plate current in the third stage.

 

3. Complete these sentences, using the correct variant:

1. Amplifiers in use nowadays

a) include only one stage,

b) include several stages.

 

2. A three-stage amplifier uses

a) three triodes connected in parallel.

b) three triodes connected in series.

 

3. The grid of each tube is insulated

a) by means of a coil.

b) by means of a capacitor.

 

4. The voltage variation is transferred

a) through a tube.

b) through a capacitor.

 

5. The circuit uses

 a) a different grid bias.

b) a common grid bias.

 

4. Answer the following questions:

 

1. How many stages do amplifiers include?

2. What are the main parts of a three-stage amplifier?

3. By what means are the grids of the tubes insulated?

4. What type of grid bias is employed?

5. In what way is the voltage variation transferred?

 

Практическое занятие 18. Электромагнитное реле

Lesson 18. Electromagnetic Relay

1. Read and learn the words:

 

Spring - пружина

cross-section - поперечное сечение

to close - замыкать, закрывать

close to - близко к (от)

to move - двигаться, приводить в движение

to switch on - включать

to switch off - выключать

various - различный, разнообразный

 

Read and translate the text.