Lab 1 – Build and Simulate Logic Circuits

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ECE 2029 INTRODUCTION TO DIGITAL CIRCUIT DESIGN
Lab 1 – Build and Simulate Logic Circuits
OBJECTIVE
1) To study the function of basic logic gates: AND, OR, INVERT, NAND, XOR, and NOR.
2) To study the representation of these functions by truth tables, logic diagrams and Boolean algebra.
3) To build and simulate logic circuits, observe and verify the output response.
THEORY
AND A multi-input circuit in which the output is 1 only if all inputs are 1. The symbolic
representation of the AND gate is shown in Fig. 1a.
OR A multi-input circuit in which the output is 1 when any input is 1. The symbolic
representation of the OR gate is shown in Fig. 1b.
INVERT The output is 0 when the input is 1, and the output is 1 when the input is 0. The
symbolic representation of an inverter is shown in Fig. 1c.
NAND AND followed by INVERT. The symbolic representation of the NAND gate is shown in
Fig 1d.
NOR OR followed by INVERT as shown in Fig 1e.
EX-OR The output of the Exclusive –OR gate, is 0 when it’s two inputs are the same and its
output is 1 when its two inputs are different.
Truth Table Representation of the output logic levels of a logic circuit for every possible
combination of levels of the inputs. This is best done by means of a systematic
tabulation.
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EQUIPMENT
A computer connected to internet.
SIMULATION USING TINKERCAD FROM AUTODESK
 Tinkercad is a free, online 3D design and 3D printing app for everyone. It helps you to prototype
your electronic designs completely within the browser, before building them in real life.
Visit https://www.tinkercad.com/, create an account and log in. No installation required.
Watch the tutorials on how to get started on TinkerCAD at the links provided in the pre-lab.
 Logisim – already installed on machines in AK 317 and AK113. Also available for FREE at the
following link: https://sourceforge.net/projects/circuit/files/latest/download.
Logisim is a logic simulator which permits circuits to be designed and simulated using a graphical
user interface.
Watch the tutorials on how to get started on Logisim at the links provided in the pre-lab.
COMPONENTS
1) IC Type 7432 Quadruple 2-input OR gates
2) IC Type 7408 Quadruple 2-input AND
gates
3) IC Type 7400 Quadruple 2-input NAND
gates
4) IC Type 7402 Quadruple 2-input NOR
gates
5) IC Type 7486 Quadruple 2-input XOR
gates
6) IC Type 7404 Hex Inverters/NOT gate
Note: See Fig. 2 for pin configurations.
Part 1: Verifying Digital Logic using Tinkercad
OR, AND, NAND, NOR, and XOR gates.
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1. Use one gate for each IC 7400 (NAND), 7402 (NOR), 7408 (AND), 7432 (OR), 7486 (XOR) and verify
the logic. See Fig. 2 to identify input and output pins for each gate. Pins 7 and 14 are ground (0 V)
and Vcc (5 V).
2. [IC 7400] Connect input pins 1 and 2 using jumper wires to apply logic (0GND, 15V). Connect
output pin 3 to LED as shown in Fig 3 as an example for the NAND gate.
Remember: LED ON = Logic 1 (High) and LED OFF = Logic 0 (Low)
Fig. 3
3. Apply the logic levels 0 and 1 in the sequence shown in table 1. Record the output logic levels.
Repeat the recordings for each digital logic gate.
Table 1 Output Response
Input Pins Output Pin
Pin 1 Pin 2
Pin 3
OR AND NAND NOR XOR
0 0
0 1
1 0
1 1
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4. Use an inverter gate from IC 7404 whose input pin is pin 1 and whose output pin is pin 2. Apply the
logic levels 0 and 1 in the sequence shown in table 2. Record the output logic levels.
Part 2: Verify the Rules and regulations of Boolean Algebra using Logisim
1. Using digital logic gates, design a digital circuit to verify the following expressions:
1. A+0 = A
2. A+1 = 1
3. A .0 = 0
4. A .1 = A
5. A+A = A
6. A+A’ = 1
7. A.A = A
8. A.A’ = 0
9. A’. B’ = (A+B)’
10. A’+B’ = (A.B)’
2. Build the following circuit using Logisim and verify the logic. Record the values in the table below:
D
F
E
Fig. 5
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Table 3 Output Response of Circuit in Fig. 5
Inputs Outputs
A B C D E F Q
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
3. Verify the recorded values for Q in the table 3 by analyzing the circuit using Logisim and get the
Boolean expression for Q.
Q =
Part 3: 2-bit input Seven Segment Display
Watch the video at the following link and repeat it.
https://youtu.be/C1omzzwVdhM
Note: Submission details are available on the sign-up sheet.