# Switching Theory

Switching Theory allows us to comfortably understand the relationship between Boolean algebra and two-level logic functions through digital logic doors. Switching theory can be used to further develop the theoretical knowledge and concepts of digital circuits. Digital logic gates that can switch inputs and outputs between two different logical values, 0 and 1, can be mathematically defined using Boolean algebra. Switches or relays from logic circuit elements can also represent two digital logic conditions, "high" or "low", using electromechanical contacts. The implementation of switching functions in digital logic circuits is nothing new, but it can help us better understand how a single digital logic door works. Digital logic gates are the basic building blocks where digital electronic circuits and microprocessor-based systems are made.

## What is Switching Theory?

As you know, we can turn the lights on through the switch. At this point this will be done with the signal outputs "1" and "0" obtained when we switch our key. But a switch can be a complex mechanical or electromechanical element used to control the flow of a signal in both directions.

### Switching Theory of Key Normally Open

In this simple example, the lamp (L) is connected to the feed with the normally on S1 switch. If the S1 switch is not pressed and therefore on, the current (I) will not flow. So the lamp doesn't light up. If the S1 switch is pressed, the current flows throughout the circuit and the lamp (L) lights up. Actually, it's as simple as that. Then let's get the circuitry right.

### Switching Theory of Keys Normally Serialized

In this simple example, the lamp (L) lights up only when both switches are pressed at the same time. In other cases, if only the key with the code "A" is pressed, the lamp will not light up as the circuit will still be open.

### Switching Theory of Keys Normally In Parallel State

In this simple example, the lamp (L) does not light up only when both switches are not pressed at the same time. In other cases, even if a button is pressed, our lamp will light up. In this article, we actually gained general knowledge about switching theories by using the keys in our digital circuit. Of course, this issue can become even more complicated. This will now vary depending on your work pace.