Elenco Understanding Logic Gates - Manual (Page 11)

U18
NAND Gate
NAND gates are used in digital logic circuits to perform an inverted logical multiply. When one of the
inputs is low (0), the output is high. The output will only be low (0) when both inputs are high.
A
Q
B
1
1
1
1
1
2
2 2 2
2
2
2
0
This circuit demonstrates how the NAND Gate
(U18) works. Connect one end of the red and
black jumper wires to the A & B inputs on U18
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 low (0,
either green LED is off), then the Q output on
U18 will be high (1), and the red LED (D1) will be
on. The output logic is exactly the opposite of
the AND gate, hence this gate is called the
NOT
AND or NAND Gate
Input (A) Input (B) Output (Q)
0 0 1
0 1 1
1 0 1
1 1 0