Republic of the Philippines
BATANGAS STATE UNIVERSITY
Alangilan, Batangas City, Philippines 4200
ECE 405 - DIGITAL PRINCIPLES AND LOGIC DESIGN
College of Engineering, Architecture and Fine Arts
Laboratory
Activity no.1
Submitted by:
Abaja, Noeleen Claire
ECE-2201
Submitted to:
Engr. Cyrus Peter M. Lim
Instructor
A.Y. 2021-2022
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OBJECTIVES:
1. Verify the truth table of the NOT gate.
2. Verify the truth table of the two-input AND gate.
3. Verify the truth table of the two-input OR gate.
4. Know and be familiar with the different characteristic of a TTL (TransistorTransistor-Logic) gate.
MATERIALS:
1. Voltmeter/voltage probe
2. Ammeter/current probe
3. DC Power Source
4. Ground
5. Oscilloscope
6. 7404 Inverter (not gate)
7. 7408 2 input AND gate
8. 7432 2 input OR gate
9. LED
10. 47 Ohm resistor
Figure A: Components for Circuit Simulation
Figure B: Voltage and Current Probes
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PROCEDURE:
Part I: Verifying the truth table of the NOT gate (7404)
1. Connect a LED with a 47 ohm resistor in series at the 7404’s output.
2. Connect the 7404’s input to ground.
3. Measure the output voltage of the 7404 using the voltmeter.
4. Record in Table 1.
Figure 1.1: NOT Gate Input Connected to Ground
5. Connect the 7404’s input to the +5V dc power source
6. Measure the output voltage of the 7404 using the voltmeter.
7. Record in Table 1.
Figure 1.2: NOT Gate Input Connected to +5V DC Power source
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Table 1: Record of Measurements of the NOT Gate Circuits
Input
Connection
GND
+5V
Logic Value
Output Voltage
0
5V
Logic Value of
the Output
1
1
0V
0
Part II: Verifying the truth table of the AND gate (7408)
1. Connect a LED with a 47 ohm resistor in series at the 7408’s output.
2. Connect both inputs of the 7408 to ground.
3. Measure the output voltage of the 7408 using the voltmeter.
4. Record in Table 2.
Figure 2.1: AND Gate Input 1 and 2 Connected to Ground
5. Connect input 2 to ground and input 1 to the +5V source
6. Measure the output voltage of the 7408 using the voltmeter.
7. Record in Table 2.
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Figure 2.2: AND Gate Input 2 Connected to Ground and Input 1 Connected to
+5V DC Power source
8. Connect input 1 to ground and input 2 to +5V source
9. Measure the output voltage of the 7408 using the voltmeter.
10. Record in Table 2.
Figure 2.3: AND Gate Input 1 Connected to Ground and Input 2 Connected to
+5V DC Power source
11. Connect both inputs of the 7408 to the +5V source
12. Measure the output voltage of the 7408 using the voltmeter.
13. Record in Table 2.
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Figure 2.4: AND Gate Input 1 and 2 Connected to +5V DC Power source
Table 2: Record of Measurements of the AND Gate Circuits
I1
I2
Logic
Value of I1
GND
GND
0
0
0V
Logic
Value of
the Output
0
GND
+5V
+5V
GND
0
1
1
0
0V
0V
0
0
+5V
+5V
1
1
5V
1
Logic
Value of I2
Output
Voltage
Part III: Verifying the truth table of the OR gate (7432)
1. Connect a LED with a 47 ohm resistor in series at the 7432’s output.
2. Connect both inputs of the 7432 to ground.
3. Measure the output voltage of the 7432 using the oscilloscope.
4. Record in Table 3.
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Figure 3.1: OR Gate Input 1 and 2 Connected to Ground
5. Connect input 2 to ground and input 1 to the +5V source
6. Measure the output voltage of the 7432 using the oscilloscope.
7. Record in Table 3.
Figure 3.2: OR Gate Input 2 Connected to Ground and Input 1 Connected to
+5V DC Power source
8. Connect input 1 to ground and input 2 to +5V source
9. Measure the output voltage of the 7432 using the oscilloscope.
10. Record in Table 3.
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Figure 3.3: OR Gate Input 1 Connected to Ground and Input 2 Connected to
+5V DC Power source
11. Connect both inputs of the 7432 to the +5V source
12. Measure the output voltage of the 7432 using the oscilloscope.
13. Record in Table 3.
Figure 3.4: OR Gate Input 1 and 2 Connected to +5V DC Power source
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Table 3: Record of Measurements of the OR Gate Circuits
Logic
Value of I2
Output
Voltage
Logic
Value of
the Output
I1
I2
Logic
Value of I1
GND
GND
GND
+5V
0
0
0
1
0V
5V
0
1
+5V
GND
1
0
5V
1
+5V
+5V
1
1
5V
1
Part IV: Familiarizing the TTL parameters of the Logic Gates
1. Search for the datasheet of each logic gate mentioned in Table 4.
2. Record each parameter (with units) in Table 4.
Table 4: TTL parameters of the Logic Gates
Logic Gate
NOT
VOH
2.4 V
VOL
0.4 V
VIL
0.8 V
VIH
2V
IOL
16mA
IOH
-0.4mA
IIL
-1.6mA
IIH
40µA
OR
2.7 V
0.5 V
0.8 V
2V
8mA
-0.4mA
-0.36mA
20µA
AND
2.4 V
0.4 V
0.8 V
2V
16mA
-0.8mA
-1.6mA
40µA
DISCUSSION OF RESULTS:
The results of this laboratory activity were recorded in assigned tables shown after
each procedure:
The record of measurements and values for the 7404 NOT logic gate is shown in
Table 1. This includes the input and output voltage with its logical values. The results
show that when the input of the NOT gate was connected to the ground, the measured
output voltage by the voltmeter is 5V which indicates a logic value of 1. On the other
hand, when the input was connected to the +5V DC source, the output voltage reading
changed to 0V which indicates a logic value of 0.
The record of measurements and values for the 7408 AND logic gate is shown in
Table 2. This includes the input and output voltage with its logical values. The results
show that when one of either inputs of the AND gate was connected to the ground, the
measured output voltage by the voltmeter is 0V which indicates a logic value of 0.
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However, when both inputs were connected to the +5V DC source, it is only then that the
output voltage reading changed to 5V which indicates a logic value of 1.
The record of measurements and values for the 7432 OR logic gate is shown in
Table 3. This includes the input and output voltage with its logical values. The results
show that when one of either inputs of the OR gate was connected to the 5V DC source,
the measured output voltage by the voltmeter is 5V which indicates a logic value of 1.
However, when both inputs were connected to the ground, it is only then that the output
voltage reading changed to 0V which indicates a logic value of 0.
The TTL Parameters of the three simulated logic gates were shown in Table 4.
Based on the researched values, it is reflected that 7404 NOT gate and 7408 AND gate
were almost identical across all parameters except the source current (IOH). On the other
hand, the 7432 OR gate has the same values with the NOT gate in 3 parameters only
which were the voltage input low (VIL), voltage input high (VIH), and the source current
(IOH).
CONCLUSION:
This laboratory experiment has verified through Multisim simulations of circuit
designs, the truth tables of the 3 basic logic gates which are NOT, OR, and AND gates. In
simulation, the 7404 component was used for the NOT gate which exhibits that the
output voltage yields to be the inverse voltage of the input. Meanwhile, the 7408 AND
gate automatically resulted to a logic output of 0 if one of either inputs were connected to
the ground and only yielded output voltage with logic value of 1 if both the inputs were
connected to the voltage source. On the other hand, the 7432 OR gate automatically
resulted to a logic output of 1 if one of either inputs were connected to the voltage source
and only yielded output voltage with logic value of 0 if both the inputs were connected to
the ground. Lastly, the TTL parameters recorded for the discussed logic gates were based
on research provided by pioneers of electronics.
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