Editing Digital-to-analog converter (section)

==Applications==
[[File:8 bit DAC.svg|thumb|A simplified functional diagram of an 8-bit DAC]]
DACs and ADCs are part of an [[enabling technology]] that has contributed greatly to the [[digital revolution]]. To illustrate, consider a typical long-distance telephone call. The caller's voice is converted into an analog electrical signal by a [[microphone]], then the analog signal is converted to a digital stream by an ADC. The digital stream is then divided into [[network packet]]s where it may be sent along with other [[digital data]], not necessarily audio. The packets are then received at the destination, but each packet may take a completely different route and may not even arrive at the destination in the correct time order. The digital voice data is then extracted from the packets and assembled into a digital data stream. A DAC converts this back into an analog electrical signal, which drives an [[audio amplifier]], which in turn drives a [[Speaker (audio equipment)|speaker]], which finally produces sound.

===Audio===
[[File:Cd-player-top-loading-and-DAC.jpg|thumb|right|Top-loading [[CD player]] (top) and external digital-to-analog converter (bottom) from the same company.]]
[[File:DAC in the box.jpg|thumb|A 1990s external DAC from [[Audio Alchemy]] as an add-on for CD players, having only about 12&nbsp;cm width, intended to improve the sound of older or less expensive players.]]

Most modern audio signals are stored in digital form (for example [[MP3]]s and [[CD]]s), and in order to be heard through speakers, they must be converted into an analog signal. DACs are therefore found in [[CD player]]s, [[digital music player]]s, and PC [[sound card]]s.

Specialist standalone DACs can also be found in high-end [[hi-fi]] systems. These normally take the digital output of a compatible CD player or dedicated [[Transport (recording)|transport]] (which is basically a CD player with no internal DAC) and convert the signal into an analog  [[line-level]] output that can then be fed into an [[amplifier]] to drive speakers.

Similar digital-to-analog converters can be found in [[digital speakers]] such as [[USB]] speakers and in [[sound card]]s.

In [[voice over IP]] applications, the source must first be digitized for transmission, so it undergoes conversion via an ADC and is then reconstructed into analog using a DAC on the receiving party's end.

===Video===
Video sampling tends to work on a completely different scale altogether thanks to the highly nonlinear response both of cathode ray tubes (for which the vast majority of digital video foundation work was targeted) and the human eye, using a "gamma curve" to provide an appearance of evenly distributed brightness steps across the display's full dynamic range - hence the need to use [[RAMDAC]]s in computer video applications with deep enough color resolution to make engineering a hardcoded value into the DAC for each output level of each channel impractical (e.g. an Atari ST or Sega Genesis would require 24 such values; a 24-bit video card would need 768...). Given this inherent distortion, it is not unusual for a television or video projector to truthfully claim a linear contrast ratio (difference between darkest and brightest output levels) of 1000:1 or greater, equivalent to 10 bits of audio precision even though it may only accept signals with 8-bit precision and use an LCD panel that only represents 6 or 7 bits per channel.

Video signals from a digital source, such as a computer, must be converted to analog form if they are to be displayed on an analog monitor.  As of 2007, analog inputs were more commonly used than digital, but this changed as [[flat-panel display]]s with [[DVI]] and/or [[HDMI]] connections became more widespread.{{Citation needed|date=October 2011}} A video DAC is, however, incorporated in any digital video player with analog outputs.  The DAC is usually integrated with some [[computer storage|memory]] ([[RAM]]), which contains conversion tables for [[gamma correction]], contrast and brightness, to make a device called a [[RAMDAC]].

=== Digital potentiometer ===
A device that is distantly related to the DAC is the [[digitally controlled potentiometer]], used to control an analog signal digitally.

===Mechanical===
[[File:IBM Selectric II typewriter.ogv|thumb|IBM Selectric typewriter uses a mechanical digital-to-analog converter to control its typeball.]]

A one-bit mechanical actuator assumes two positions: one when on, another when off. The motion of several one-bit actuators can be combined and weighted with a [[whiffletree]] mechanism to produce finer steps. The [[IBM Selectric]] typewriter uses such a system.<ref>{{cite web |author=Brian Brumfield |url=https://www.youtube.com/watch?v=uTjxwVfx8GA | archive-url=https://web.archive.org/web/20151229033401/https://www.youtube.com/watch?v=uTjxwVfx8GA| archive-date=2015-12-29 | url-status=dead|title=Selectric Repair 10-3A Input: Keyboard |date=Sep 2, 2014 |via=YouTube |df=ymd-all}}</ref>

=== Communications ===
DACs are widely used in modern communication systems enabling the generation of digitally-defined transmission signals. High-speed DACs are used for [[mobile communications]] and ultra-high-speed DACs are employed in [[optical communications]] systems.