Lecture Notes - Chapter 10

The Transformer

(These Lecture Notes are for courses using the book the Complete Electronics Self-Teaching Guide with Projects. Instructors of courses using that text are permitted to use these Lecture Notes as-is or adapt them for their use).

  • Transformer Basics
    • Discuss the use of coils and a core to form a transformer (figure 10.1).
    • Introduce the term: primary coil.
    • Introduce the term: secondary coil.
    • Discuss the fluctuating magnetic field generated by a alternating current flowing through the primary coil.
    • Discuss the induction of current in the secondary coil by the fluctuating magnetic field.
      • Direct current flowing through the primary coil does not generate a fluctuating magnetic field, therefore direct current will not induce a current in the secondary coil
    • Introduce the term: in phase (figure 10.3).
    • Introduce the term: out of phase (figure 10.4).
    • Discuss the phase difference between the outputs of a center tap secondary coil (figure 10.5).
    • Introduce the term: center tap(figure 10.5).
    • Introduce the term: turns ratio (TR).
      • The ratio of the input to output voltage voltage is the same as the ratio of the number of turns in the primary coil to the number turns in the secondary coil.
    • Discuss the equation for this relationship.
    • Introduce the term: step-down transformer.
    • Introduce the term: step-up transformer.
    • Introduce the term: isolation transformer.
    • Discuss how the voltage output from secondary coil depends upon whether the center tap is grounded (figure 10.9).
    • Introduce the term: efficiency.
    • Discuss the equation to calculate the ratio of input and output currents.
  • Transformers in Communications Circuits
    • Discuss the idea of using transformers to match impedance.
    • Review the equation used to calculate the ratio of the input impedance to the ratio of the output impedance.
    • Discuss the calculations to determine the turns ratio needed to match a generator to a load.


This page includes material extracted, by permission of the publisher, Wiley Publishing, from Complete Electronics Self-Teaching Guide with Projects, ISBN: 9781118217320.

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