INC 253 Digital and electronics laboratory I
Laboratory 10
Counter Circuit Design and 7-Segment LED
Author:
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Co-Authors:
1. …………………………… ID …………………
2. …………………………… ID …………………
3. …………………………… ID …………………
Experiment Date: ………………… Report received Date: …………………
For Instructor
Comments
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Pre lab
Full
10
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Results
15
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Discussion
Questions
Conclusion
25
10
5
Total
65
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Marks
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Department of Control System and Instrumentation Engineering
Faculty of Engineering
King Mongkut’s University of Technology Thonburi
Objectives
1. To understand the principle and functions of “common anode type” and “common cathode type”
7-segment LED.
2. To understand how to design the counter circuits together with the display section.
Equipments Required
1. Training board
Devices Required
1. Common anode 7-segment LED
2. Common cathode 7-segment LED
3. IC no.: 7490, 7447, 7408
4. Resistance : 330 
Pre-Lab Preparation
1. Design counter circuits in the experiment item 2, 4 and 6 and write the circuits down to
the Fig.2, 3 and 4 respectively.
Procedure
1. First step, find the position (a, b, c, d, e, f, g and dp) of each legs of the given 7-segment LED, as
shown in Fig.1. Then, check that the given 7-segment LED is “common anode” or “common
cathode” by using multi-meter. (Do not use range 1, since it can damage the LED). After
that record the result in Table 1.
10
f
e
1
6
a
g
b
d
c
dp
5
Fig.1 7-segment LED display
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INC, KMUTT
Lab. 10: Counter Circuit Design and 7-Segment LED
Table 1: 7-segment LED display
Pin No.
Segment
Pin No.
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
Type of LED #1 : ___________________
Segment
Type of LED #2 : ___________________
2. From the datasheet of IC 7490 and 7447, design the 1 digit decade counter circuit. The input
signal is TTL clock pulse. Then, display the counting value to the 7-segment LED. Write the
complete designed circuit down to the Fig.2.
Hint:
1) Before design the circuit, please study the datasheet of IC 7447 and check that
the output of the IC can connect to the given type of 7-segment LED or not. If
not, you need to design the additional section until IC 7447 can interface to
given type of 7-segments.
2) Resistance 330  should be connected between the IC 7447 output and the 7segments LED input.
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INC, KMUTT
Lab. 10: Counter Circuit Design and 7-Segment LED
Fig.2 Decade counter
3. Make an actual circuit as designed in Fig.2 to check the actual result. After complete this step,
please call the instructor to check and verify the result.
4. From the circuit in Fig.2, modify the circuit to be “Mod-6 counter”. Then, write the designed
circuit down to Fig.3.
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INC, KMUTT
Lab. 10: Counter Circuit Design and 7-Segment LED
Fig.3 Mod-6 counter
5. Make an actual circuit as designed in Fig.3 to check the actual result. After complete this step,
please call the instructor to check and verify the result.
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INC, KMUTT
Lab. 10: Counter Circuit Design and 7-Segment LED
6. From the datasheet of IC 7490 and 7447, design the counter circuit, which can count from 00 to
99, and display the counting value to 7-segment LED. Write the complete designed circuit down
to the Fig.4.
Fig.4 00 to 99 counter
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INC, KMUTT
Lab. 10: Counter Circuit Design and 7-Segment LED
7. Make an actual circuit as designed in Fig.4 to check the actual result. After complete this step,
please call the instructor to check and verify the result.
Questions
1. What are the advantages and disadvantages of the “common anode” and “common cathode” type
7-segments LED?
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2. From the given datasheet of IC 7447 and 7448, describe the difference functions between these 2
ICs.
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3. Design the count-down counter, which will count from 5 – 0  5 – 0, by using IC 7490 and
display the counting value to common anode type 7-segment LED.
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INC, KMUTT
Lab. 10: Counter Circuit Design and 7-Segment LED