Week1&2 comm., for engineering technicians

Communications For
Engineering
Technicians
Week No. 1& 2

Contents
• How to interpret as an engineer the
following :

1. Electronic Circuits.
2. Electrical Circuits.
3. Communication Circuits

Prepared By Communication Team

How can we interpret the engineering
drawings in the electrical department?
 In our department we need to know the steps that let us able to
interpret the engineering information.
 So in this session we will produce to you the steps that we and
you will follow in interpreting the engineering information which
are:
1. You need to determine the electrical/Electronic/communication
components.
2. Then know the its main purpose of these components in these
circuits.
3. Then after you collect these information, we will know the
purpose of these circuits.
 Note that we will implement these steps in the following types of
circuits:
1- Electronic circuits.
2- Electrical circuits.
3- Communication circuits.


1- Electronic Circuits:

 At first we need to review in all the electronic components that we
studied in the previous years, So in this session we will produce to
you the steps that we and you will follow in interpreting the
engineering information which are:
Wires and connections- 1
Component

Circuit Symbol

Function of Component

Wire

To pass current very easily from one part of a
.circuit to another

Wires joined

A 'blob' should be drawn where wires are
connected (joined), but it is sometimes omitted.
Wires connected at 'crossroads' should be
staggered slightly to form two T-junctions, as
shown on the right.

Wires not joined

In complex diagrams it is often necessary to
draw wires crossing even though they are not
connected. I prefer the 'bridge' symbol shown
on the right because the simple crossing on the
left may be misread as a join where you have
forgotten to add a 'blob'!


Power Supplies- 2
Component

Circuit Symbol


Cell

Supplies electrical energy.
The larger terminal (on the left) is positive (+).
A single cell is often called a battery, but strictly a
battery is two or more cells joined together.

Battery

Supplies electrical energy. A battery is more than
one cell.
The larger terminal (on the left) is positive (+).

DC supply

DC = Direct Current, always flowing in one
direction.

AC supply

AC = Alternating Current, continually changing
direction.

Fuse

circuit breaker

A safety device which will 'blow' (melt) if the
current flowing through it exceeds a specified
value.
a device that automatically breaks an electrical
circuit whenever the circuit becomes overloaded or
an unintentional short circuit occurs


Power Supplies- 2
Component

Circuit Symbol


Transformer

Two coils of wire linked by an iron core.
Transformers are used to step up (increase) and
step down (decrease) AC voltages. Energy is
transferred between the coils by the magnetic field
in the core. There is no electrical connection
between the coils.

Earth
(Ground)

A connection to earth. For many electronic circuits
this is the 0V (zero volts) of the power supply, but
for mains electricity and some radio circuits it
really means the earth. It is also known as ground.


Switches- 3
Component

Circuit Symbol


Push Switch
(push-to-make)

A push switch allows current to flow only when the
button is pressed. This is the switch used to operate a
doorbell.

Push-to-Break Switch

This type of push switch is normally closed (on), it is
open (off) only when the button is pressed.

On-Off Switch
(SPST)

SPST = Single Pole, Single Throw.
An on-off switch allows current to flow only when it
is in the closed (on) position.

2-way Switch
(SPDT)

SPDT = Single Pole, Double Throw.
A 2-way changeover switch directs the flow of current
to one of two routes according to its position. Some
SPDT switches have a central off position and are
described as 'on-off-on'.

Dual On-Off Switch
(DPST)

DPST = Double Pole, Single Throw.
A dual on-off switch which is often used to switch
mains electricity because it can isolate both the live
and neutral connections.


Switches- 3
Component
Reversing Switch
(DPDT)

Relay

Circuit Symbol

DPDT = Double Pole, Double Throw.
This switch can be wired up as a
reversing switch for a motor. Some
DPDT switches have a central off
position.
An electrically operated switch, for
example a 9V battery circuit
connected to the coil can switch a
230V AC mains circuit.
NO = Normally Open,
COM = Common, NC = Normally
Closed.


4- Resistors
Component
Resistor

Circuit Symbol

A resistor restricts the flow of current, for example
to limit the current passing through an LED. A
resistor is used with a capacitor in a timing circuit.
Some publications still use the old resistor symbol:

Variable Resistor
(Rheostat)

This type of variable resistor with 2 contacts (a
rheostat) is usually used to control current.
Examples include: adjusting lamp brightness,
adjusting motor speed, and adjusting the rate of
flow of charge into a capacitor in a timing circuit.

Variable Resistor
(Potentiometer)

This type of variable resistor with 3 contacts (a
potentiometer) is usually used to control voltage. It
can be used like this as a transducer converting
position (angle of the control spindle) to an
electrical signal.

Variable Resistor
(Preset)

This type of variable resistor (a preset) is operated
with a small screwdriver or similar tool. It is
designed to be set when the circuit is made and
then left without further adjustment. Presets are
cheaper than normal variable resistors so they are
often used in projects to reduce the cost.


5- Capacitors
Component

Circuit Symbol


Capacitor

A capacitor stores electric charge. A capacitor is
used with a resistor in a timing circuit. It can also
be used as a filter, to block DC signals but pass AC
signals.

Capacitor, polarised

A capacitor stores electric charge. This type must
be connected the correct way round. A capacitor is
used with a resistor in a timing circuit. It can also
be used as a filter, to block DC signals but pass AC
signals.

Variable Capacitor

A variable capacitor is used in a radio tuner.

Trimmer Capacitor

This type of variable capacitor (a trimmer) is
operated with a small screwdriver or similar tool.
It is designed to be set when the circuit is made
and then left without further adjustment.


6- Diodes
Component

Circuit Symbol

A device which only allows current to flow in one

Diode
direction.
LED
Light Emitting Diode

A transducer which converts electrical energy to
light.
A special diode which is used to maintain a fixed

Zener Diode
voltage across its terminals.

Photodiode

A light-sensitive diode.


7- Transistors
Component

Circuit Symbol

A transistor amplifies current. It can be used with

Transistor NPN

other components to make an amplifier or
switching circuit.
A transistor amplifies current. It can be used with

Transistor PNP

other components to make an amplifier or
switching circuit.

Phototransistor

A light-sensitive transistor.


Activity No.1
 USE YOUR TECHNICAL INFORMATION ABOUT CIRCUIT/NETWORK
DIAGRAM TO INTERPRET THESE CIRCUITS:
Circuit No.1


Circuit No.2


Circuit No.3


Circuit No.4


2- Electrical Circuits:
 At first we need to review in all the electrical components that we
studied in the previous years, So in this session we will produce to
you the steps that we and you will follow in interpreting the
engineering information which are:
: Logic Gates- 1
).Logic gates process signals which represent true (1, high, +Vs, on) or false (0, low, 0V, off

Component

NOT

AND

Circuit Symbol

A NOT gate can only have one input. The
'o' on the output means 'not'. The output of
a NOT gate is the inverse (opposite) of its
input, so the output is true when the input is
false. A NOT gate is also called an inverter.
An AND gate can have two or more inputs.
The output of an AND gate is true when all
its inputs are true.


: Logic Gates- 1

Component
NAND

Circuit Symbol

A NAND gate can have two or more inputs.
The 'o' on the output means 'not' showing
that it is a Not AND gate. The output of a
NAND gate is true unless all its inputs are
true.

OR

An OR gate can have two or more inputs. The
output of an OR gate is true when at least one
of its inputs is true.

NOR

A NOR gate can have two or more inputs.
that it is a Not OR gate. The output of a NOR
gate is true when none of its inputs are true.


: Logic Gates- 1

Component

Circuit Symbol

An EX-OR gate can only have two inputs.

XOR

The output of an EX-OR gate is true when its
inputs are different (one true, one false).
An EX-NOR gate can only have two inputs.

XNOR

that it is a Not EX-OR gate. The output of an
EX-NOR gate is true when its inputs are the
same (both true or both false).


Activity No.2
Circuit No.1


Circuit No.2

A
B
Y

HOSSAM hedait

Circuit No.3

A

Y
B


3- Communication Circuits:
 At first we need to review in all the communication components
that we studied in the previous years, So in this session we will
produce to you the steps that we and you will follow in interpreting
the engineering information which are:
1- Communication Components:
Component

Circuit Symbol


Router

A Router is an internetworking device which
operates at OSI Layer 3. A Router
interconnects network segments or entire networks
and passes data packets between
networks based on Layer 3 information. The
router, by default, is an open device.
Services must be turned off or secured.

Switch

Switches connect LAN segments, use a table of
MAC addresses to determine the
segment on which a datagram needs to be
transmitted, and reduce traffic. Switches,
which typically operate at Layer 2, can be
categorized as stackable or chassis based.


Component

Circuit Symbol


Hub

Hubs, or multiport repeaters, are legacy devices
which combine connectivity with the
amplifying and re-timing properties of repeaters.
Hubs operate at Layer one of the OSI.
It is typical to see 4, 8, 12, and up to 24, ports on
multiport repeaters. This allows many
devices to be cheaply and easily interconnected.

Server

In most networks, servers are the brains of the
operation while networking devices
provides the nervous system of the business. It is
very important that these resources
are protected against attacks.

Corporate
Headquarter

The Corporate Headquarter (HQ) is where the
primary network resides. The HQ is a
central point of connection between branch offices,
business partners, remote users, and
the Internet. Devices located at the HQ are most
critical to protect.


Component

Circuit Symbol


Personal
Computer

The Personal Computer (PC) has only been
around for 25 years and has greatly
changed the world. Functionality, performance,
and storage have greatly increased. With
the advent of the Internet, PCs have become
commonplace in governments, businesses,
schools, and homes. Unfortunately, with increased
capabilities and connectivity, security
vulnerabilities in applications and operating
systems are a big problem. It is these
vulnerabilities, which are exploited by hackers
today. With broadband services such as
DSL and Cable, the attacks have increased
dramatically.

Network Cloud

The Network Cloud represents a wide area
network (WAN) or the Internet. Network traffic
can traverse private and public links depending on
the established service and
connections. Also, data can traverse a single
Internet service provider (ISP) or multiple
ISPs.


Component

Modem

IOS Firewall

Firewall

Circuit Symbol


A modem is a device which provides connectivity
to the ISPs network access server. A modem can
terminate dial-up connections, xDSL, or Cable
connections.
The Cisco IOS Firewall, provides robust,
integrated firewall, intrusion detection, and VPN
functionality for every perimeter of the network.
The Firewall Feature Set is available for most
Cisco routers including the 800, 1600, 1700, 2500,
2600, 3600, 7100, and 7200 series routers, however
some features may not be available on low end and
legacy router models.

Firewall provides large enterprises and service
providers with unmatched security, reliability, and
performance within a switch chassis.


Component
Ethernet Link

Circuit Symbol

Ethernet Links provide connectivity for the entire
network. These links interconnect routers,
switches, printers, PCs, laptops, servers, and other
end devices. Current Ethernet links operate at
from 10Mbps to 10Gbps. Ethernet can run over
fiber and copper.

Wan Link

WAN Links provide connectivity to the Internet.
WAN technologies can be classified as packet
switched, circuit switched or cell switched.
Technologies include dial-up, ISDN, X.25, xDSL,
Satellite, Cellular, Cable, Frame Relay, SMDS,
ATM, SONET. Speeds range from 28Kbps to
10Gbps.

Attacker

Attackers access the network either internally or
externally. Remember that 75 percent of
the attacks come from within the network.
Attackers can be curious users, corporate
spies, government operatives, careless users,
disgruntled employees, or elite hackers.


Activity No.3
Circuit No.1


Activity No.4
IDENTIFY THE STANDARD
SYMBOLS AND CONVENTIONS YOU
HAVE USED BY ADDING BRIEF
NOTES TO THE HARD COPY OF
YOUR ACTIVITIES.


THANK YOU FOR LISTENING
Questions


Week1&2 comm., for engineering technicians

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