Unit 8: Electrical operations
LO3: Be able to construct electrical and electronic
circuits
Interpreting circuit diagrams
Learner activity sheet
Activity 1:
Circuit diagrams show how electrical and electronic components are connected together to form a
working circuit that performs a particular function. They comprise of interconnected circuit symbols
representing individual components.
A technique for interpreting the operation of the circuit is working from left to right (input to output) or
right to left (output to input).
Look at the circuit diagram below. Throughout this whole exercise you are going to read and interpret
the circuit diagram.
FS1
TR1
D1
Vin
D2
REG1
Vout
GND
~
VR1
C1
D3
D4
C2
R1
Vcc
R2
C3
LED1
GND
Begin by answering the following question (you may need to do some research):
What overall function does this circuit perform?
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Activity 2:
The table below shows, for each component in the circuit, its value or part number.
Complete the table by identifying the type of component shown.
Label
Part number or Value
FS1
2A / 240 V
VR1
275 V diameter 10 mm
TR1
240 V/12 V 5VA
D1 to D4
IN4001
C1
2200 F / 25 V Electrolytic
C2
0.1 F / 25 V Ceramic
C3
10 F / 25 V Electrolytic
R1
4.7 K
R2
1K
REG1
7805
LED1
L-7113LID
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Component Type
Activity 3:
For Activity 3 identify the function of each component (or group of components) in the circuit (working
from left to right) by completing the table below. In this way you will be able to understand how the
circuit works.
Label
Function in circuit
FS1
VR1
TR1
D1 to D4
C1
REG1
R1
C2
C3
R2
LED1
Complete the Activity by writing a short summary of how the overall circuit works.
You may wish to investigate the data sheets for some of the components shown in the circuit diagram.
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