Analogue Electronics 1 2017 (PDF)

12/09/2017

Electronics 1
• This course is in two parts
• A. Circuit theory – Keith Ryden
– This part will cover the fundamentals of electronic
circuits and their analysis

• B. Analogue electronics – Philip Evans
– This part will cover practical analogue electronics
and their design and analysis
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Analogue electronics: Course Syllabus
• Fundamentals
Resistive networks, voltage and current sources, Thevenin and Norton
equivalent circuits, current and voltage division, input resistance, output
resistance, coupling and decoupling capacitors, maximum power transfer, RMS
and power dissipation, current limiting and over voltage protection

• Components and active devices
Components vs elements and circuit modelling, real and ideal elements.
Introduction to sensors and actuators, self-generating vs modulating type
sensors, simple circuit interfacing

• Diodes and diode circuits
Diode characteristics and equations, ideal vs real. Signal conditioning clamping
and clipping, rectification and peak detection, photodiodes, LEDs, Zener
diodes, voltage stabilisation, voltage reference, power supplies
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Level 1 Module
Electronics 1

Analogue Electronics
Phil Evans

Lecture 1 – Resistive networks
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Fundamental properties
• Begin with a look at the fundamental
properties of circuits
– Resistance
– Current
– Voltage

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Resistance
• Resistance is the property of a circuit that opposes the flow of
current in response to a voltage.
• Measured in Ohms = volts/ampere
– i.e. a voltage is required to generate current flow
• Ohms law describes this relationship:
V = IR I = V / R R = V / I

• This is a linear relationship where R is (approximately)
constant passing through the origin
I
V
Slope of the line ∂I/ ∂V = 1/R = conductance (measured in Siemans = Ω-1)

5

Current
• Absolute quantity
– Measurement of number of electrons passing a point per
second
– e = 1.6 x 10-19 C
– 1A ≈ 0.6 x 1019 electrons/second
– 1pA ≈ 6 million electrons/second

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Voltage
• Relative measurement
– Always need a reference point → potential difference
between 2 points
– Ohm’s law relates resistance, current and the voltage drop
across the resistor → V1 – V2 = IR
•
•
•
•

Power at any moment = V(t) x i(t) 2
Power dissipated in a resistor = V (t ) = i 2 (t ) R
R
For an AC supply V(t) = Vmax sin (ωt)
Instantaneous current = V (t )
V sin(ωt )
R

= I (t ) =

max

R

= I max sin(ωt )

Note that current and voltage are in phase
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Resistors
• Two terminal devices with a specified value of resistance
• Values measured in ohms, kΩ, MΩ etc.
• Available in preferred values in ranges E6, E12, E24, E48, E96
– Divides ranges into 6,12,24,48,96 values

• Colour codes
–
–
–
–

1st band – 1st digit
2nd band – 2nd digit
3rd band – multiplier
4th band – tolerance

Must also specify resistor power handling capacity
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Resistor colour code

www.electronicshub.org

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Resistor Preferred Value Range
E6
10

E12
10

E24
10

11

12

12

13

15

15

15

16

18

18

20

E96
10.0
10.2
10.5
10.7
11.0
11.3
11.5
11.8
12.1
12.4
12.7
13.0
13.3
13.7
14.0
14.3
14.7
15.0
15.4
15.8
16.2
16.5
16.9
17.4
17.8
18.2
18.7
19.1
19.6
20.0
20.5
21.0

E6

E12

E24

22

22

22

24

27

27

30

33

33

33

36

39

39

43

E96
21.5
22.1
22.6
23.2
23.7
24.3
24.9
25.5
26.1
26.7
27.4
28.0
28.7
29.4
30.1
30.9
31.6
32.4
33.2
34.0
34.8
35.7
36.5
37.4
38.3
39.2
40.2
41.2
42.2
43.2
44.2
45.3

E6

E12

E24

47

47

47

51

56

56

62

68

68

68

75

82

82

91

E96
46.4
47.5
48.7
49.9
51.1
52.3
53.6
54.9
56.2
57.6
59.0
60.4
61.9
63.4
64.9
66.5
68.1
69.8
71.5
73.2
75.0
76.8
78.7
80.6
82.5
84.5
86.6
88.7
90.9
93.1
95.3
97.6

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Web Resources
• Various web resources to practice resistor identification:
– http://www.funtrivia.com/playquiz/quiz2664721e821c8.html
– https://en.wikipedia.org/wiki/List_of_electronic_color_code_mnemon
ics - Bad Booze Rots Our Young Guts But Vodka Goes Well

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Temperature stability
• Typically 0.019%/°C – 0.05%/°C
• Time stability 50 ppm/month (0.005%)/month
• Voltage limits also apply e.g. 0.25W – 350Vmax typically

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Combinations of Resistors:
Resistive networks
• In series
– RT = R1 + R2 + R3
– Beware of tolerances – 100 kΩ (5%) + 1 kΩ (5%) ≠ 101 kΩ
Due to the tolerance

• In parallel
– 2 resistors
– 3 resistors

1
1
1
R1R 2
=
+
⇒ RT =
RT
R1
R2
R1 + R 2
RT =

R1R2 R3
R1 R2 + R2 R3 + R1R3
1 power less in denominator

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Combinations of Resistors
• Short cuts for mental arithmetic
5kΩ ≡ 2 x 10k in parallel or 10k//10k=5k
So 10k//5k ≡ 3 x 10k = 10k/3 = 3k33
R1//R2: if R1 = nR2 then RT = R1/(n+1)
Or if mR1 = nR2 = R then RT = R/(n+m)
e.g. 22k/33k ≡ (3x66k)//(2x66k)
(m)

(n)

= 5x666k in parallel = 66k/(3+2) = 66k/5 = 13k2
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Class examples
Find the resistance between A and B

A
5Ω
30 Ω

30 Ω

B

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Class examples
Find the resistance between A and B

A
30 Ω

30 Ω

30 Ω

50 Ω
B

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Class examples
Find the resistance between A and B

A
2 kΩ

4.5 kΩ

1.4 kΩ

2.7 kΩ

B

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Class examples
Find the resistance between A and B

A
320 kΩ

200 kΩ

160 kΩ

150 kΩ

B

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