Elenco Understanding Logic Gates and Circuits - Manual (Page 10)

U
1
7
Project 3: OR Gate
This circuit demonstrates how the OR Gate
(U17) works. Turn the slide switch (S1) on.
Connect the loose ends of the red and
black wires to either low voltage (denoted
as a “0”) or high voltage (denoted as a
“1”). If either input A
OR input B are high
(1), then the Q output will be high (1), and
the red LED (D1) will be on.
OR gates are used in digital logic circuits to perform a logical add. When one of the inputs is high (1), the
output is high. The output will only be low (0) when both inputs are low.
1
0
1
1
1
1 1
2
2
2
2
2
3
3
2
A
Q
B
Input (A) Input (B) Output (Q)
0 0 0
0 1 1
1 0 1
1 1 1
The output of an OR gate is often
represented as the sum of the inputs, so
Q = A+B .
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2
2
1
3
2
A
B
Q