Lecture Notes - Chapter 2
(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).
Diodes
- Understanding Diodes
- Discuss semiconductor materials.
- Introduce N and P type semiconductor materials.
- Discuss the structure of a diode (figure 2.3).
- Introduce the term: PN junction
- The P type material is the anode.
- The N type material is the cathode.
- Discuss the flow of electric current through a diode
- Introduce the schematic symbol for a diode (figure 2.4).
- A PN junction conducts electricity in one direction
only (figure 2.5).
- Introduce the term: forward-biased diode.
- Introduce the term: reverse-biased diode(figure 2.8).
- Introduce the term: perfect diode.
- Discuss the similarity of a forward-biased diode to a
closed switch.
- Discuss the similarity of a reverse-biased diode to a
open switch.
- Discuss Project 2-1, The Diode
- Introduce the V-I curve of a diode (figure 2.10).
- Introduce the term: knee voltage (figure 2.16).
- Discuss the use in current limiting resistors.
- Discuss the relationship of knee (or threshold) voltage
to the type of semiconductor material used in the diode.
- Introduce the term: voltage drop.
- Circuits with a diode in series with a resistor (figure
2.17).
- Discuss the equation for the voltage drop across the
resistor.
- Discuss the equation for the current through the
resistor.
- Review the concept that the current through two
components in series is equal. Therefore the current through
the diode is equal to the current through the resistor.
- Discuss the equation for finding the power dissipated
through a diode.
- Circuits with a diode in parallel with a resistor (figure
2.20).
- Discuss the equation for the total current.
- Review the concept that the voltage across components in
parallel is equal.
- Discuss the equation for the current through the
parallel resistor.
- Discuss the equation for the current through the diode.
- Diode Breakdown
- Circuits with a reverse-biased diode, in series with a
resistor (figure 2.23).
- Discuss the V-I curve for a reverse-biased diode (figure
2.24).
- Introduce the term; Peak Inverse Voltage (PIV).
- Inside the Diode
- Introduce the term; Depletion Region
- Depletion regions act as electrical insulators,
preventing the current flow.
- When a diode is forward biased the depletion region shrinks,
allowing current flow.
- When a diode is reverse biased the depletion region expands,
preventing current flow, unless the peak inverse voltage is
exceeded.
- Zener Diodes
- Zener diodes are reverse biased in circuits (figure 2.26).
- Zener diodes have a precise peak inverse voltage determined
by the manufacturer.
- Zener diode placed parallel to a load in circuits to provide a
constant voltage, and therefore a constant current across the
load (figure 2.29).
- Discuss Project 2.2: The Zener Diode Voltage Regulator
- Review the circuit (figure 2.33).
- Comment on the expected drop in voltage output (VS) of the 9
volt battery with time.
- Review how VL and IL are expected to remain constant, but IZ
is expected to drop as VS drops.
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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