The NAND gate

The next circuit is the NAND gate

This is the same symbol as the AND gate with the circle from the NOT gate added to it's output.

This gate is used when a logical FALSE or 0 is required when all inputs are high.

An example of where this could be used is indicating the output hoppers from a machine. Every hopper which is full emits a signal and when all are full, the output turns OFF an indicator to tell the operator that there is no more room. I know this is contrived, but understanding a NAND gate (as with the other gates) helps understand all digital logic as it builds into very complex circuits.

A schematic for a NAND gate is below. Of note is that this is the same circuit as the AND gate with a transistor added to invert or NOT what comes out of the AND portion.

The truth table for this gate. The table shows that the output of this gate is the exact opposite of the AND gate.

A	B	Output
0	0	1
0	1	1
1	0	1
1	1	0