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1. Basic of Electronics
Things to be covered:
• What is electricity
• Voltage, Current, Resistance
• Ohm’s Law
• Capacitors, Inductors
• Semiconductors
• Diodes
• Transistors

2. What is Electricity
• Everything is made of atoms
• There are 118 elements, an atom is a single part of an
element
• Atom consists of electrons, protons, and neutrons

3. • Electrons (- charge) are attracted to protons (+ charge), this
holds the atom together
• Some materials have strong attraction and refuse to loss
electrons, these are called insulators (air, glass, rubber, most
plastics)
• Some materials have weak attractions and allow electrons to be
lost, these are called conductors (copper, silver, gold,
aluminum)
• Electrons can be made to move from one atom to another, this
is called a current of electricity.

4. • Surplus of electrons is called a
negative charge (-). A shortage
of electrons is called a positive
charge (+).
• A battery provides a surplus of
electrons by chemical reaction.
• By connecting a conductor
from the positive terminal to
negative terminal electrons will
flow.

5. Voltage
• A battery positive terminal (+) and a negative terminal (-). The
difference in charge between each terminal is the potential
energy the battery can provide. This is labeled in units of volts.
Water Analogy

6. Voltage, Current, and Resistance
• Water flowing through
a hose is a good way
to look at electricity
Water is like Electrons in a
wire (flowing electrons is
called Current)
Pressure is the force pushing
water through a hose –
Voltage is the force
pushing electrons through a
wire
Friction against the hole walls
slows the flow of water –
Resistance is the force that
slows the flow of electrons

7. Voltage Sources:

8. • Voltage is like differential pressure,
always measure between two points.
• Measure voltage between two points
or across a component in a circuit.
• When measuring DC voltage make
sure polarity of meter is correct,
positive (+) red, negative (-) black.

9. Ground

10. Exercise
• Measure DC voltage from power supply using multimeter
• Measure DC voltage from power supply using oscilloscope
• Measure DC voltage from battery using multimeter
• Measure AC voltage from wall outlet using a multimeter
• Measure AC voltage from wall outlet using an oscilloscope
Effective or Root Mean Square Voltage
(Measured with multimeter)
ERMS=0.707xEA
E

11. Current
• Uniform flow of electrons thru a circuit is called current.
WILL USE CONVENTIONAL FLOW NOTATION ON
ALL SCHEMATICS

12. Types of Current
• There are 2 types of current
– The type is determined only by the direction the
current flows through a conductor
• Direct Current (DC)
– Flows in only one direction negative toward positive
pole of source
• Alternating Current (AC)
– Flows back and forth because the poles of the source
alternate between positive and negative

13. AC Current Vocabulary

14. Circuits
• A circuit is a path for current to flow
• Three basic kinds of circuits
– Open – the path is broken and interrupts
current flow
– Close – the path is complete and current
flows were it is intended
– Short – the path is corrupted in some way
and current does not flow were it is intended

15. Circuits

16. • To measure current, must break circuit and install meter in line.
• Measurement is imperfect because of voltage drop created by meter.

17. Resistance
• All materials have a resistance that is dependent on cross-
sectional area, material type and temperature.
• A resistor dissipates power in the form of heat

18. Various resistors types

19. When measuring resistance, remove
component from the circuit.

20. Resistor Color Code

21. • Determine the resistance of various resistors of unknown
value using the resistor color code
• Using the multimeter, compare the specified resistance and
measured resistance
• Using the multimeter to examine the characteristics of various
potentiometers
Exercise

22. Ohm’s Law

23. Prototyping Board
Example of how components are
Inserted in the protoboard

24. Exercise
• Calculate the total current and voltage drop across each resistor shown in Figure 1
• Build the circuit in Figure 1 on the prototype board
• Measure the total circuit current and voltage drops across each resistor and compare
the calculated and measured values

25. Capacitance
Battery
Capacitor
Unit = Farad
Pico Farad - pF = 10-12F
Micro Farad - uF = 10-6F
A capacitor is used to store charge for a short amount of time

27. Capacitor Charging

28. Capacitor Discharge

29. Inductance

31. The Diode
• The semi-conductor phenomena
• Diode performance with AC and DC
currents
• Diode types
– Basic
– LED
– Zenier

32. The Diode
The semi-conductor
phenomena
• Electrons in a metal form a “sea” of
electrons that are relatively fee to move
about.
• Semiconducting materials like Silicon and
Germanium have fewer free electrons.
• Impurities added to semiconductor
material can either add free electrons or
create an absence of electrons (holes).

33. The Diode
The semi-conductor
phenomena
• Consider the bar of silicon at the right.
– One side of the bar is doped with negative
material (excess electrons). The cathode.
– The other side is doped with positive material
(excess holes). The anode
– In between is a no man’s land called the P-N
Junction.

34. The Diode
The semi-conductor
phenomena
• Consider now applying a negative
voltage to the anode and positive
voltage to the cathode.
• This diode is reverse biased meaning
no current will flow.

35. The Diode
The semi-conductor
phenomena
• Consider now applying a positive
voltage to the anode and a negative
voltage to the cathode.
• This diode is forward biased meaning
current will flow.

36. The Light Emitting Diode
• In normal diodes, when electrons combine
with holes heat is produced.
• With some materials, when electrons
combine with holes, photons of light are
emitted.
• LEDs are generally used as indicators
though they have the same properties as a
regular diode.

37. Zener Diode
• A Zener diode is
designed through
appropriate doping
so that it conducts at
a predetermined
reverse voltage.
– The diode begins to
conduct and then
maintains that
predetermined
voltage
• The over-voltage and
associated current
must be dissipated
by the diode as heat
9V 4.7V

38. The Transistor
(Electronic Valves)
• How they works, an inside
look
• Basic types
– NPN
– PNP
• The basic transistor circuits
– Switch
– Amplifier

39. The Transistor
base
collector
emitter
collector
collector
base

40. The Transistor
N P N
collector emitter
base e -
e -
forward bias
conducting
e -

41. The Transistor
N P N
collector emitter
base e -
e -
reverse bias
no-conducting

42. The Transistor
• There are two basic types of
transistors depending of the
arrangement of the material.
– PNP
– NPN
• An easy phrase to help
remember the appropriate
symbol is to look at the arrow.
– PNP – pointing in proudly.
– NPN – not pointing in.
• The only operational difference
is the source polarity.
PNP
NPN

43. Conclusion
• Not really - your journey to understand
basic electronics has just begun.
• This course was intended to introduce you
to some concepts and help you become
knowledgeable in others.

44. University of Pennsylvania

45. Thank you…