İzmir
zmir University of Economics
EEE
E 205 Fundamentals of Electrical Circuits Lab
EXPERIMENT 1
Resistors
A. Background
Different resistor structures has been developed to meet different system
specifications. For different power dissipation ranges, resistors of differerent
materials are produced as shown in Fig. 1.1. When an application requires a
resistor of 1 Watt power rating, possibly a wire wound resistor is chosen (Fig.
1.1a). Fig. 1.1(b) shows 1W metal
me
film resistor. In Fig.1.1(c) and (d), carbon
car
composition resistors of ½ W and ¼ W are shown.
shown. For low power applications
on the printed circuit boards, surface mount resistors may be used during
production as shown in Fig.1.1(e).. When a circuit requires resistor of equal
resistances, single-in-lin
line package (SIP) resistors of Fig.1.1(f) may be used as
shown in.
(a) 10 W Wire Wound Resitor
(b) 1W Metal Film Resistor
(c) ½ W Carbon Composition Resistor
(d) ¼ W Carbon Composition Resistor
Surface
Mount
Resistor
(e) Surface Mount Resistors
(f) Single-in-Line
Line Package (SIP)
Resistors
Fig. 1.1. Resistors of Different Type
The value of a resistor is usually indicated by 4 color band over the resistor as
shown in Fig. 1.2(a).
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Gold (5%)
Silver (10%)
Tolerance
Multiplier
2nd Digit
1stDigit
No color
(20%)
(a)
(c)
(b)
Fig. 1.2. Resistor Color Codes (4 band)
The first band indicates 1st digit, second band is for 2nd digit and the third
band indicates the multiplier. The numerical values corresponding to the color
bands are listed in Fig.1.2(b).
Since the first color band is brown (1) and the second band is black (0), the
first two digits of the are 10. The multiplier color band being red (2) means
the number of zeros added will be 2. So the value of the resistor given in Fig.
1.2(a) is determined as:
1st Digit
2nd Digit
Multiplier
Color
Brown
Black
2
Value
1
0
00
Code
Resistance
1000
1 kΩ
Hence above resistor has a value of 1 kΩ. The above resistor
or has a tolerance
color of gold; which means error (tolerance) in the resistance value is ±5%. If
the tolerance band color is silver, than it means the tolerance
tol rance in the resistance
value is ±10%.
10%. No color means ±20% tolerance.
Gold (5%)
Silver (10%)
No color
(20%)
Tolerance
Multiplier
3rd Digit
(a)
2nd Digit
1st Digit
(c)
(b)
Fig. 1.3. Resistor Color Codes (5 band)
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The color band scheme for 5-color bands is given in Fig. 1.3. For the resistor
given in Fig. 1.3.(a), first color band is brown (1), the second band is black
(0), and the third band is black (0), so the first three digits are 100. The
multiplier color band being red (2) means the number of zeros added will be 2.
So the value of the resistor given in Fig. 1.2(a) is determined as:
1st Digit
2nd Digit
Color
Brown
Black
Black
2
Value
1
0
0
00
Multiplier
Code
Resistance
10000
10 kΩ
The above resistance has a tolerance color of gold; which means tolerance is
±5%.
The resistance values for each tolerance band is fixed. The nominal values for
the first two digits used in each tolerance band are listed in Table 1.1.
Table 1.1. Nominal Resistance Values
±5%
10
11
12
13
15
16
18
20
22
24
27
30
33
36
39
43
47
51
56
62
68
75
82
91
±10%
±20%
10
12
15
18
22
27
33
39
47
56
68
82
10
15
22
33
47
68
Therefore a resistance of value of 1.1 kΩ can be found in ÷5% tolerance
range. If such a resistor is required and if ±10% resistors are available, the
suitable choices may be 1kΩ or 1.2 kΩ resistances.
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B. Preliminary Work
1.
Find the resistance values of the resistors given in Fig.1.4
Resistance Value
Tolerance
Fig. 1.4. Resistors
2.
Color the resistance color bands (4 band) of the resistors given in Fig.1.5.
(a) 120 Ω (±10%)
(b) 4.3 kΩ (±5%)
(c) 68 kΩ (±20%)
(d) 1.2 MΩ (±10%)
Fig. 1.5. Resistors with 4 color band
3.
Color the resistance color bands (5 band) of the resistors given in Fig.1.6.
(e) 120 Ω (±10%)
(f) 4.3 kΩ (±5%)
(g) 68 kΩ (±20%)
(h) 1.2 MΩ (±10%)
Fig. 1.6. Resistors with 5 color band
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4.
Calculate the equivalent resistances of the resistor combinations given in
Fig.1.7.
Req
Req
10
kΩ
2.5 kΩ
30
kΩ
(a)
30
kΩ
(b)
Req=
Req=
Req
Req
10
kΩ
10
kΩ
30
kΩ
(c)
Req=
10
kΩ
10
kΩ
30
kΩ
(d)
Req=
Fig. 1.7. Series and Paraller Conected Resistors
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C. Experimental Work
C. 1. Determine and measure the values of R3-R4-R5-R6 resistors and
write them to Table 1.2. given below.
Table 1.2
Resistor
Color Code
Multimeter
Reading
Difference
Error (%)
R3
R4
R5
R6
C. 2. Explain the differences between the color codes and the measured
values. Are they consistent the tolerance specifications of the
resistors?
C. 3. R7 is a 5-band resistor and reading method of a 5-band resistor
has been explained in Bacground Section. Determine and
measure the values of R3-R4-R5-R6 resistors and write them to
Table 1.3. given below.
Table 1.3
Resistor
Color Code
Multimeter
Reading
Difference
Error (%)
R7
R8
R9
R10
C. 4. Explain the differences between the color codes and the measured
values. Are they reasonable?
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C. 5. Build the given circuit onto the boards.
C. 6. Calculate the equivalent resistor seen from the terminals of
voltage source.
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C. 7. How
can
you
measure
the
equivalent
resistor
experimentally? What is the measured equivalent resistor?
C. 8. Calculate the current and voltage of Rx and Ry resistors. Then
measure with multi-meter.
C. 9. Calculate the power absorbed by Rx and Ry.
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