In this module you are going to learn about Transformers, Diodes, Power Supplies, Transistor Basics. I also have some additional reading for you

Transformers are simply two (or more) inductors coupled by common Magnetic field.
Page 5-17 to 5-21 and page 6-8 of your course book provides a good introduction to transformers, in addition the following Web page Electronics 2000 Chapter 7

One of the most important things to learn about transformers is how to calculate the transformer ratio, this is covered quite well on page 5-18 of your course book,
In addition the following web page covers Transformer Ratios

Diodes are very useful devices that only allow Current to flow in one direction. Diodes are covered in your course book on pages 6-9 to 6-12. The most important things to learn about diodes are the meanings of the following terms, Peak Inverse Voltage (PIV), Maximum Average Forward Current and Forward Voltage Drop. As these terms are used to work out a Diodes operating parameters.

Current normally Flows From the Anode (+) to the Cathode (-).

Diodes are also covered on the following Web sites
The Diode
Diode Behaviour

Diodes are commonly used for rectification (Converting AC currents to DC currents) which leads us on to Power Supplies.

AC Power Supplies are used in almost all electronic equipment to convert the AC mains (in Ireland 230 Volts AC @ a frequency of 50 Hz ) to the correct DC operating Voltage for the equipment.

A simple AC power supply (PSU for short.) Consists of Three sections, The transformer, The Diode rectifier and the Filter

Here is a nice little piece of software which allows you to computer model various types of power supplies. Duncan Amp PSU Designer2

A transistor is a 3 terminal device that has the ability to amplify current.

Here are the Symbols for the 2 most common types of transistor

The value of this current gain is typically about 100 so for a 1 mA change in the Base-Emitter Current the current flowing between the Collector and the Emitter will change by 100 mA.

There are three basic rules that have to be met for a transistor to provide gain.

1/ The collector must be more positive (more negative in the case of a PNP transistor.) than the emitter.

2/ The base-emitter and base-collector circuits behave like diodes

3/ A Small current flowing into the base controls a much larger current flowing into the collector.

Here is a Web page with an example of several radio circuits using transistors.

Please read the following sections of your course book

7-8 Filters, note that a PSU filter circuit is a low pass filter.

8-1 to 8-5 Signals and Emmisons, Now read 7-10 to 7-12.