---
categories:
  - Electronics
tags: [circuits]
---

# Digital circuits

Ultimately every process in a computer is the product of a digital [circuit](/Electronics_and_Hardware/Analogue_circuits/Circuits.md) that is working on binary values. In contrast to electrical circuits, digital circuits are not represented in an [analogue](/Electronics_and_Hardware/Analogue_and_digital.md) fashion.

Analogue circuits work on the basis of real continuous phenomena in the world: charges and currents. As a result, the key properties of a circuit - voltage, current and resistance - can vary over a wide range of values. This is the reason that we require components like batteries and resistors: to control the natural flow of current and ensure that it only runs within desired parameters.

In a standard electrical circuit, voltage, current and resistance can vary over a wide range of values however in the binary context we want to deal with discrete values (zeros and ones) which can be fed into the various [logic gates](/Electronics_and_Hardware/Digital_circuits/Logic_gates.md).

We therefore need a way to represent 'on' and 'off' as single quantities. We do this by stipulating that a given voltage corresponds to 'on' (high) and another corresponds to 'off' (low). Of course these are not really discrete values since voltage is inherently analogue but we basically binary-encode them. Formally 'on' has a voltage of 1 and 'off' has a voltage of 0. In reality 'on' tends to be within 2-5V depending on the circuit design and anything between 0 - 0.8V is considered off.

The [transistor](/Electronics_and_Hardware/Digital_circuits/Transistors.md) is the electrical component that enables us to represent given voltage ranges as being 'on' or 'off'.
