Light Sensor is a device that reacts to light. There are different types of light sensor. The one used here
is a phototransistor. When there is no light, electric current cannot pass through it. And therefore it is
like a switch that is switched off. When there is light falling on it, electric current can pass through it. It is
then like a switch that is switched on. This way a light control circuit can be made.
Circuit symbol
Resistor uses different color rings to represent the value (resistance). The 1st and 2nd rings represent
the digit. The 3rd ring represents the multiplier as table shown. The 4th ring represents tolerance that
means the precision of the resistance. Example: The color rings are Brown, Red, Brown and Gold which
represents resistance is 120 ohm, tolerance 5% (Ω).
Transistor is a semi-conductor device that is used to amplify a signal and to open or close it in a
circuit. There are two types of transistors, namely NPN and PNP, with similar circuit symbol. The
transistor is a fundamental device commonly used in the modern electronic equipment. It has the
fastest response and accurate action as amplifier and switching device, and can act as an individual
device / component or as a part of IC (Integrated Circuit). IC is built of over a thousand to million
transistors.
V. 01 – 01/02/2024
Color Identification Code
Color
1st
Black
0
Brown
1
Red
2
Orange
3
Yellow
4
Green
5
Blue
6
Purple
7
Grey
8
White
9
Brown
Red
Gold
Silver
KNS130
rd
2nd
3
- multiplier
0
x 1
1
x 10
2
x 100
3
x 1000
4
x 10000
5
x 100000
6
x 1000000
7
8
9
x 0.1
x 0.01
7
Tolerance
+/- 1%
+/- 2%
+/- 5%
+/- 10%
©Velleman nv