# LOGIC GATES

Logic gates are in every IC and microchip today, they practically control modern electronics.Personally I like to stick with capacitors and resistors and simple stuff like that but thanks to instructables user rtty21 I learned how to make a NOR gate and now I have countless ideas of what to with them, so here I will discuss some uses of different gates and how to make them. You should at least have a basic knowledge of logic gates to understand this.

A/B=input(s)
Q=output
1=high
0=low

-=sorry about some of the messed up pictures, I'm trying to get it resolved=-
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## Step 1: NOT gate

This is perhaps the most simple gate, it has one input and one output. It is known as an inverter because its output is opposite to its input. A representing the input, Q representing the output: Q=NOT A (thus the name "NOT"). There is an IC that uses six NOT gates called a 4049 CMOS hex inverter buffer.

A  | Q
1 | 0
0 | 1

## Step 2: AND gate

The AND gate only has a "true" output of both of its inputs are "true". This means thats will only be high if both the inputs are high, if one is high and one low the output will be low. So Q=A & B (thus the name AND gate).

A | B | Q
0 | 0 | 0
1 | 0 | 0
0 | 1 | 0
1 | 1 | 1

## Step 3: NAND gate

The NAND gate is the opposite of an AND gate, the name stands for "NOT AND". One of the inputs have to be low to get a high, two highs is a low. The 4011 CMOS IC uses four NAND gates. The NAND gate can be used to make any other gate and it's possible to make a computer of NAND gates alone. Q = (NOT) A AND B (thus the name NAND).

A | B | Q
0 | 0 | 1
0 | 1 | 1
1 | 0 | 1
1 | 1 | 0
jrevard10 months ago
The XNOR (and all other logic gate chips I've ever seen) has its own voltage and ground inputs that the user supplies. This voltage source is independent of the inputs for each gate on the chip. So the power is always available and the internal circuitry determines if the gate inputs will allow current to flow through to the outputs.
Liam.great981 year ago
Thanks, I now understand a lot better. However, I don't understand one thing. Let's say we're using the XNOR gate. If A=0 and B=0 then Q=1. How? Where does Q get power from if A and B are low?
MROHM3 years ago
(removed by author or community request)
Jimmy Proton (author)  MROHM3 years ago
thanks! Both of those are true, in fact they are in a book that teaches logic gates!
Kurt Vonnegut3 years ago
Thank you for making this
Jimmy Proton (author)  Kurt Vonnegut3 years ago