Make a NOT gate from a NAND gate
The NAND gate is called universal because every other gate can be built from it. The first step is the simplest gate of all, NOT: the output must be the opposite of the input.
Truth table
| A | Y |
|---|---|
| 0 | 1 |
| 1 | 0 |
Try it Click the inputs to change them.
Y1
The idea
Look at the NAND truth table and only at the rows where both inputs are equal. When both are 0, NAND gives 1. When both are 1, it gives 0. That is exactly what an inverter does. So the question is: how do you make sure both inputs of the NAND always get the same signal?
Hints and solution
Try on your own first. Each hint gives away a little more.
- NAND gives 0 only when both of its inputs are 1.
- What does a NAND do when both inputs get the same signal?
- Wire A to both inputs of one NAND.