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EEN 1200 L – Digital Fundamentals

Merrimack College

Laboratory 2 – Introduction to 7404 Hex Inverter & Basic Gates & Timing Diagrams

NAME _____________________________

The purpose of this laboratory experiment is to:

I. Get practice in wiring integrated circuits on the trainers

II. Generate “Truth Tables” for basic gates.

III. Use these logic elements to generate a high level logic element.

IV. Generate the “Truth Table”, and identify the logic element.

V. Generate timing diagrams for the basic gates.

Part A: Introduction to 7404 Hex Inverter (IC)

Hook up the 7404 Hex Inverter integrated circuit, and look at the input and output of ONE of the inverters

(pins 1 and 2). Note: There are 6 inverters in the same package, hence the term Hex. See pin-outs of the 7404 Hex Inverter at the last page.

A

B

Z

A

B

Z

A

B

Z

A

B

C

Z

Z

A

B

Logic 1

Logic 1

A

B

Z

A-1) Using the built in signal generator (RED Trainer), place a 1 kHz and TTL input to the inverter. [Be sure to connect the IC (pin 14) to 5VDC and (pin 7) to the ground (GND)].

Look at the input and output together on the scope using 2 Volts DC per division. Draw what you see:

Output Waveform

Input Waveform

Note: Label the x-axis and y-axis

A-2) What is the period? ________________milli-seconds

A-3) Use 5.0 VDC per division on the scope, then read the following on the scope. Draw what you see below.

Voltage amplitude of input=____________

Voltage amplitude of output=____________

Frequency of input=____________

Frequency of output=____________

Period of input=____________

Period of output=____________

Note: Label the x-axis and y-axis

Part B: Basic Gates & Timing Diagrams

A

B

Z

A Truth Table consists of all possible logic inputs and the output that corresponds to each logic input.

In the following, an AND Gate with logic inputs A & B with a logic output Z is shown:

A input	B input	Z output
0	0	0
1	0	0
0	1	0
1	1	1

The timing diagram is discussed at length in Chapter 3. The basic timing diagrams for the logic gates we are using in this lab allow for a visual reading of how the logic functions. By viewing the timing diagram, the reader can see what outputs result from the different possible combinations of inputs. The truth table can easily be determined by looking at the basic timing diagram.

B-1) Follow steps of part A-1 to hook up the 7408 of Quad 2-Input AND gate, then connect input A to SW7 and input B to SW6 then generate a truth table below by measuring output Z using voltmeter. Connect a wire from the output pin to any of the 8 bits LED display located on the upper right corner of the function generator. Note: There are 4 AND gates in the same package.

A

B

C

Z

Input A	Input B	output Z
0	0
1	0
0	1
1	1

B-2) Connect a 1 kHZ, TTL to input A and keep input B connected to SW6. First, put a “1” on input B. Look at input A, the square wave, and the output of the AND using an oscilloscope. Second, put a “0” on input B. Look at input A, the square wave, and the output of the AND using an oscilloscope. Draw both cases on the graph below

First case (input B=1)

Draw the input & the output

Second case (input B=0)

Draw the input & the output

Note: Label the x-axis and y-axis

B-3) Follow steps of part B-1 to hook up the 7432 Quad 2-Input OR gate, and generate a truth table. Note There are 4 OR gates in the same package.

A input	B input	Z output

B-4) Connect a 1 kHZ, TTL to input A and keep input B connected to SW6. First, put a “1” on input B. Look at input A, the TTL, and the output of the OR gate using an oscilloscope. Second, put a “0” on input B. Look at input A, the TTL, and the output of the OR gate using an oscilloscope. Draw both cases on the graph below.

First case (input B=1)

Draw the input & the output

Second case (input B=0)

Draw the input & the output

Note: Label the x-axis and y-axis

B-5) Hook up the 7411 Triple 3-input AND gate, and generate a truth table. Note: There are 3 AND gates in the same package.

Note: To turn on any gate pin7 has to be grounded and pin14 must be connected to +5V DC power supply.

A input	B input	C input	Z output

Z

A

B

Logic 1

Logic 1

 B-5) Hook up the following circuit and generate a Truth Table.

A input	B input	Z output

Can you identify this logic element? ____________________________________

Write-up: Review and follow the lab write-up guidelines. Show me your work before you leave.

 

Z

A

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