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Or gate – Elenco Understanding Logic Gates User Manual

Page 10

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U17

OR Gate

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

1

1

1

1

2

2

2

2

2

2

2

0

This circuit demonstrates how the OR Gate
(U17) works. Connect one end of the red
and black jumper wires to the A & B
inputs on U17 and the loose ends 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, either green LED

is on), then the Q output on U17 will be
high (1), and the red LED (D1) will be on.

A

Q

B

The output of an OR gate is often
represented as the sum of the inputs, so

Q

= A+B

.

Input (A)

Input (B)

Output (Q)

0

0

0

0

1

1

1

0

1

1

1

1