Transcript Technical Basics - 1

Chelmsford Amateur Radio Society
Intermediate Course
(3) Technical Basics - 1
Components
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
1
Electronic Components
•
Nature
Amateur Radio applies Electronics to Wireless Communication
•
Items
Common Electronic Components Include:
–
–
–
–
–
•
Resistors, inc Colour code
Capacitors, Inductors, Resonant Circuits
Diodes & LEDs
Transistors
Switches, Fuses, Connectors
The Intermediate Licence expects you to be able to recognise components,
their circuit symbols, and to build and test simple circuits
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
2
Insulators, Conductors &
Semiconductors
• Conductors permit the flow of electric current
– Examples: Copper, Brass etc - (ie mainly metals)
• Metallic Conductors permit electrons to flow easily, but beware of
poor/oxidised connections (eg on Aluminium, Steel)
• Insulators don’t permit electron flow and exhibit high resistance.
– Examples: Plastics, wood, rubber, glass, ceramics
• Water may conduct (esp. when impure) and that wet insulators
therefore may conduct on their surface - a risk for outdoor work
• Semiconductors (Silicon, Germanium etc) barely conduct unless
small dopants are added to create P or N-type materials
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
3
Electrical Units
Quantity
Voltage, V
Current, I
Resistance, R
Capacitance
Inductance
Power, P
Frequency, f
Wavelength, 
Chelmsford Amateur Radio Society
Intermediate Licence Course
Unit
Volt
Amp
Ohm
Farad
Henry
Watt
Hertz
Metre
Symbol
V
aka Potential Difference
A

F
H
W
Hz
m
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
4
Unit Prefixes
Factor
trillionths
billionths
millionths
thousandths
thousands
millions
billions
SN
10-12
10-9
10-6
10-3
103
106
109
Examples: 25kV = 25000V
0.1uH = 100nH
10pF = 0.01nF
Chelmsford Amateur Radio Society
Intermediate Licence Course
Prefix
pico
nano
micro
milli
kilo
Mega
Giga
Symbol
p
n
 or u
m
k
M
G
1500mA = 1.5A
2.45GHz = 2450MHz
0.5W = 500mW
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
5
Power
Recall from
Foundation…
P Watts
V Volts I Amps
Relates Power, P
Voltage, V
P=VxI V=P/I I=P/V
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Current, I
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
6
Ohms Law
NB: Take care when
quantities in formulas
use unit prefixes
V Volts
I Amps
R Ohms
Relates Voltage, V Current, I
Resistance, R
V=IxR I=V/R R=V/I
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
7
Cells & Batteries

•
Batteries provide a source of DC power
•
Note symbols for Single Cells or Battery Packs
•
Cells store electrical energy by chemical means
•
Primary Cells can only be used once.
•
Secondary cells can be recharged. This reverses
the chemical reaction eg in Lead Acid, NiCd, LiMH
•
Beware of Leakage, Shorts esp on Lead-Acid
•
Dispose of carefully
Chelmsford Amateur Radio Society
Intermediate Licence Course
Cell

+
Battery
Murray Niman G6JYB

Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components

8
Resistors
•
Fixed Resistors traditionally
identified by Colour Code for
Value & Tolerance
•
Note that the modern BSI
Symbol is preferred to the
zigzag
Resistor
No
•
Note all the symbols opposite
for the various forms
•
Check Wattage Rating
Chelmsford Amateur Radio Society
Intermediate Licence Course
Preset
Resistor
Potentiometer
Murray Niman G6JYB
Variable
Resistor
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
9
Resistor Colour Code
•
First two Bands
give Value Digits
•
Third Band is the
Multiplier for
Factor of Ten
•
Fourth Band is
Tolerance
•
Example:-
12 x1000= 12k, 10%
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
10
Resistors in Series/Parallel
•
Resistors in Series:-
Rtotal = R1+ R2+ R3 . . .
R1
•
R2
R3
Resistors in Parallel:-
1/Rtotal = 1/R1+1/R2+1/R3 . . .
•
For Identical Resistors this simplifies to...
•
For Two Resistors:
Rtotal = R/2
R2
•
For Three Resistors:
Rtotal = R/3
R3
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
R1
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
11
Inductors & Transformers
•
Inductors are Coils of Wire which may
have air or ferrite/iron cores
•
Energy is stored in the magnetic field
•
Inductance is proportional to number of
turns, diameter, core etc
•
Inductance is in Henries eg mH, nH, pH
•
Inductors pass DC but increasingly
block AC at higher frequencies
•
Air-Core
Inductor
Iron-Cored
Inductor
Transformer
Pairs of coils can be used to create
Transformers – for PSUs, RF circuits etc
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
12
Capacitors
•
•
Capacitors are insulated plates, which can store
electric charge and energy in the electric field
Larger plate areas, the nature of materials
between the plates or smaller plate separation
will give higher capacitance
•
Capacitance is in Farads eg uF, nF, pF
•
Capacitors block DC but increasingly
pass AC at higher frequencies
•
Beware Voltage rating and polarity of
Tantalum/Electrolytic versions
•
Capacitor
Variable
Capacitor
Polarised
Capacitor
Note all the symbols opposite
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
13
Diodes
•
Diodes are PN Junctions of semiconductor
materials which only pass current one way
•
Diodes are a key item in PSUs where they
rectify AC into DC
•
Note Forward Current and Reverse Voltage
ratings, and a small forward bias Voltage Drop
•
LEDs - Light Emitting Diodes
•
Variable Capacitance Diodes – exploits PN
Junction Capacitance when reverse biased
•
Zener Diodes - have a precise Reverse Voltage
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Diode
LED
Varicap Diodes
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
14
Transistors
•
•
•
•
•
Bipolar Transistors are NPN or PNP
junctions of semiconductor material
Middle section is the ‘Base’. A small
bias current can control a larger flow
between Collector and Emitter
b
e
Bipolar NPN Transistor
In FET devices current flow between
Drain and Source is controlled
Electrostatically by the Gate voltage
Depending on the circuit, Transistors
can Amplify or Switch - or Oscillate
Integrated Circuits have arrays of
many Transistors on a single chip
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
c
d
g
s
P-Channel
Field Effect Transistor (FET)
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
15
Transistor Gain
•
•
•
Current flow in the Collector (IC) to the
Emitter can be controlled by a smaller bias
current in the Base, IB
If levels are set correctly, small variations in
base current are amplified at the output
Current Gain or ‘Beta’ is the ratio of IC/IB
ß = I C / IB
IC
base
IB
collector
emitter
NPN Transistor
or, IC = ß x IB
•
For example, a base current of 5mA in a
device with Beta=50 controls an IC of 0.25A
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
16
Miscellaneous
•
Also need to recognise symbols for
Switches, Grounds, Crystals etc, etc
Switch
SPST
Antenna
Switch
DPST
Crystal
Loudspeaker
Fuse
Earth
Chelmsford Amateur Radio Society
Intermediate Licence Course
Chassis
Lamp
Murray Niman G6JYB
Earphone
Microphone
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
17
Practicals
• Recognise Resistors by Colour Code
• Measure Resistors in Series
• Measure Resistors in Parallel
• Learn to Recognise other Components
• Soldering - correctly without damage
• Build and test board with resistors and transistor
Chelmsford Amateur Radio Society
Intermediate Licence Course
Murray Niman G6JYB
Slide Set 3: v1.2 3-May-2009
(3) Technical Basics -1: Components
18