1. Resistors Resistors can be either fixed or variable in value
Fixed resistors come in a variety of different shapes, sizes and forms
Axial lead resistors have the value of resistance printed on them or as a colour code
Surface mount resistors have a numerical code indicating a value
All resistors have a tolerance value

2. Resistors Variable resistors are called potentiometers
There is a fixed value of resistance between two terminals
The moving part of the potentiometer is called the wiper

3. Resistors Four band resistor colour code
1st band provides the first digit of the code
2nd band provides the second digit of the code
3rd band is the multiplier
4th band indicates the tolerance value

4. Resistors 2 7 x10 +/-5% Resistor colour code calculation
The first band red has a value of 2
The second band purple has a value of 7
The third band has a multiplier of x 10
The last band indicates a tolerance value of +/-5%
Resistance value is 270Ω +/-5% 2 7
x10
+/-5%

5. Resistors on PCB Resistors
(axial components
with color bands

6. Resistor Color Code
This session only focuses on ohms law
Note: A resistor with a single black-band is a zero ohm resistor 6 6

7. Resistor Color Code
PPM = Part per million
PPM 7 7

8. Resistor Color Code – Online Tools
Color to Value (with Tolerance):
Value with (Tolerance) to Color: 8 8

9. Standard Resistor Values
Electronic Industries Association (EIA) standard E24:
Standard E24 specifies resistors based on 5% tolerance (often resistor of this category has 2% tolerance now a days due to advancement of manufacturing techniques)
Standard Resistor values =
100
110
120
130
150
160
180
200
220
240
270
300
330
360
390
430
470
510
560
620
680
750
820
910
× 10M Ohms
(Where M can be any integer, positive or negative)
For other standards:

10. Resistor with Different Power Ratings
Examples:
2 Watts
1 Watt
0.5 Watt
0.25 Watt
The size indicates the power rating, NOT the resistance value

11. Resistor Examples Through-hole Resistors SMT Components
Source: Basic Electronics, Bernard Grob
Through-hole Resistors
SMT Components
(Larger size often indicates higher power rating)

12. Variable Resistor Examples

13. Resistor Code SIL (Single In-Line) network:
Ref:
SIL (Single In-Line) network:
The 4 and 7 are significant digits and the 3 is the decade, giving 47 x 1000 or 47 KW
The letter after the numbers is the tolerance. The different representations are: M=±20%, K=±10%, J=±5%, G=±2%, F=±1%.
Detail Spec:
SMD (Surface Mount Device):
The 1 and 0 are significant digits and 3 is the decade, giving 10 x 1000 or 10 KW
Direct Value:
Resistors with larger physical size are often printed the value directly on their body

14. Resistor Specifications
Value: Ohms (W)
Tolerance: % of Ohmic value
Safety Rating: Power in Watt
Shape: Axial (mostly)
Technology: Through-hole or SMD (Surface Mount Device)

15. Resistor Symbol 15