Editing Telegraph key (section)

{{short description|Electrical switch used to transmit text messages in Morse code}}
{{Refimprove|date=December 2024}}
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{{Infobox electronic component
| name              = Telegraph key
| image             = J38TelegraphKey.jpg
| caption           = A ''straight key'' style of telegraph key &ndash; {{nowrap|model '''J-38'''}}, a key used by U.S. military during World War&nbsp;II, and frequently re-used by radio amateurs
| type              = [[Electronic switch|Switch]]
| working_principle =
| invented          =
| first_produced    =
| pins              =
| symbol            = [[File:IEEE 315 Contacts, Switches, Contactors, and Relays Symbols (150).svg]]
| symbol_caption    =
}}

[[File:Wright Telegraph Key.jpg|thumb|right|a Wright Brothers telegraph key (missing its knob)]]
[[File:Morsetaste.jpg|thumb|A Morse Key from [[:de:Gustav Hasler|G.&nbsp;Hasler]], [[Bern]] (1900) first used by [[Gotthard Railway#The Gotthard railway telegraph network|Gotthard Railway]]]]

A '''telegraph key''', '''clacker''', '''tapper''' or '''morse key''' is a specialized electrical [[switch]] used by a trained operator to transmit text messages in [[Morse code]] in a [[telegraphy]] system.<ref>{{cite web |title=Telegraph Key |url=https://www.si.edu/object/telegraph-key%3Anmah_706715 |website=National Museum of American History |publisher=Smithsonian Institution |access-date=15 December 2024}}</ref>   Keys are used in all forms of [[electrical telegraph]] systems,  including landline (also called wire) telegraphy and [[Wireless telegraphy|radio (also called wireless) telegraphy]]. An operator uses the telegraph key to send electrical pulses (or in the case of modern [[Continuous wave#Radio|CW]], unmodulated radio waves) of two different lengths: short pulses, called ''dots'' or ''dits'', and longer pulses, called ''dashes'' or ''dahs''. These pulses encode the letters and other characters that spell out the message.