Editing Voice-operated switch (section)

{{Short description|Switch controlled by the sound of speech}}
In [[telecommunications]], a '''voice operated switch''', also known as '''VOX''' or '''voice-operated exchange''', is a switch that operates when sound over a certain threshold is detected.<ref>{{cite book |title=Newton's Telecom Dictionary |url=https://archive.org/details/newtonstelecomdi00harr |url-access=registration |last=Newton |first=Harry |year=2004 |publisher=CMP books |pages=[https://archive.org/details/newtonstelecomdi00harr/page/901 901] |isbn=9781578203093 }}</ref> It is usually used to turn on a transmitter or recorder when someone speaks and turn it off when they stop speaking. It is used instead of a [[push-to-talk operation|push-to-talk button]] on transmitters or to save storage space on recording devices. On [[mobile telephone|cell phones]], it is used to save [[battery (electricity)|battery]] life. Intercom systems that use a speaker in a room as both a speaker and a microphone will often use VOX on the main console to switch the audio direction during a conversation. The circuit usually includes a delay between the sound stopping and switching direction, to avoid the circuit turning off during short pauses in speech.

A special case exists, if there is enough energy to power the system directly. For example, a microphone may send a voltage high enough to directly operate a transmitter.<ref>{{Cite web|url=http://g3xbm-qrp.blogspot.com/2009/10/sound-powered-transmitters.html|title=Sound powered transmitters|date=7 October 2009}}</ref>