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You have just completed the design of a simple AND logic circuit that will activate a motor. This motor requires a high signal to start the motor. (The motor input is an active high input.)
Practice Problem
Test your circuit design at the bread board level.
First, let’s review the structure and use of a breadboard.
What You See
The Breadboard
What You Don’t See:
What You Don’t See:
The Breadboard
Horizontal strip of copper wire.
Horizontal strip of copper wire.
Horizontal strip of copper wire.
Horizontal strip of copper wire.
Two rows of short isolated vertical strips (70 single strips per row) of copper wire
Power Supply
Ground ( 0 V )
Power and ground rails
The Breadboard
+ 5 volts
5 volt horizontal panel
0 volts
+ -5 nodes per vertical column
25 nodes per horizontal row section
The Breadboard
Power Supply Power and ground rails
+ 5 volts 0 volts
+ -5 nodes per veridical column
25 nodes per horizontal row section
A node is a point where two components of a circuit can be connected.
+5 volt node connection
Ground, 0 V, node connection
Vertical Column (5 Node) :
The Breadboard
Each Vertical Column on the face of the board has a strip of metal underneath the board connecting the 5 holes. This allows 5 different circuit elements to be connected and have the same voltage value.
Each column of the breadboard is electrically isolated from its neighborEach column of the breadboard is electrically isolated from its neighbor
The Trench(A nonconductive groovewhich isolates 2 groups of vertical columns)
Chips are to be installed across the Trench
The Breadboard
The “chip”The “chip”
In this case, the chip is called a 7408 and it houses four AND logic devices.
The chip with the identification number 7408 is always a chip that contains AND devices. How many AND devices are in a 7408 chip?
The Breadboard
A
Input # 1 for AND device A
Input # 2 for AND device A
Output for AND device A
Input # 1 for AND device B
Input # 2 for AND device B
B
Output for AND device B
C
Input # 1 for AND device C
Input # 2 for AND device C
Input # 1 for AND device D
Output for AND device B
D
Input # 2 for device D
Output for device D
There are 4 AND devices in the 7408 package. The 7408 is know as a quad 2 input AND
package.
The Breadboard
Pin 1
Pin 7
Pin 14
Pin 8
In order to perform its function each chip must have a connection to the Power (5V) and to the Ground (0V)
The Breadboard
What are the possible pins that could be used for the power and ground connection?
Input # 1 AND device A
Input # 1 AND device CInput # 2 AND device A
Output AND device A
Input # 1 AND device A
Input # 2 AND device A
Output AND device A
Input # 1 AND device C
Output AND device C
Input # 1 AND device D
Input # 1 AND device D
Output AND device D
There are two pins left. One is for the power connection, the other is for the ground connection.
Which one goes to which pin?
The Breadboard
In order to perform its function each chip must have a connection to the Power (5V) and to the Ground (0V)
What are the possible pins that could be used for the power and ground connection?
Input # 1 AND device A
Input # 1 AND device CInput # 2 AND device A
Output AND device A
Input # 1 AND device A
Input # 2 AND device A
Output AND device A
Input # 1 AND device C
Output AND device C
Input # 1 AND device D
Input # 1 AND device D
Output AND device DThe terminal where the zero volt wire is connected, (the ground connection).
7
The terminal where the 5 volt wire is connected.14
-
+
Ground ( 0 Volts)
?
?
Which pin is pin number 1?
Power (+5 Volts)
Note:
If you hold the chip so you can read the label “DM 7408N”,
Which one is the pin where the 0 volts, the ground connection, is made?
Then the 5 volt pin is the last pin on the left side of the top row of pins.
Which pin is pin number 8?
Which pin is pin number 7?
How many pins does a 7408 have?
14
Where are the power and ground connections for this 7408?
The Breadboard
Which pin is pin number 14?
7
14
A ( input )
B ( input)
The Breadboard
0 Volts
Practice Problem
Test your circuit design at the bread board level.
Draw your test circuit on a piece of paper before you continue with this presentation.
1
11
04.96
Battery powered Volt meter
+
Now let’s return to the initial problem statement
You have just completed the design of a simple AND logic circuit that will activate a motor. This motor requires a high signal to start the motor. (The motor input is an active high input.)
Power (+5 Volts)
When the two inputs (input A and input B) are at logic 1 the output will be at logic 1 and the meter will display 5 volts.
A ( input )
B ( input)
The Breadboard
0 Volts
Practice Problem
Test your circuit design at the bread board level.
Draw your test circuit on a piece of paper before you continue with this presentation.
1
11
04.96
Battery powered Volt meter
+
Now let’s return to the initial problem statement
You have just completed the design of a simple AND logic circuit that will activate a motor. This motor requires a high signal to start the motor. (The motor input is an active high input.)
Power (+5 Volts)
When the two inputs (input A and input B) are at logic 1 the output will be at logic 1 and the meter will display 5 volts.
