Editing Tonewheel (section)

{{Short description|Electromechanical apparatus for generating electric musical notes}}
{{Refimprove|date=August 2011}}
[[Image:Tonewheel-p.svg|thumb|Simplified diagram of how a tonewheel works]]
[[Image:Goldschmidt tone wheel.jpg|thumb|Goldschmidt tone wheel (1910), used as an early [[beat frequency oscillator]]]]

A '''tonewheel''' or '''tone wheel''' is a simple electromechanical apparatus used for generating electric [[musical note]]s in electromechanical [[electronic organ|organ]] instruments such as the [[Hammond Organ|Hammond organ]] and in telephony to generate audible signals such as [[ringing tone]]. It was developed by [[Thaddeus Cahill]] for the [[telharmonium]] c. 1896 and patented in 1897.<ref>{{US Patent|580035A}}</ref> It was reinvented around 1910 by [[Rudolph Goldschmidt]] for use in pre–[[vacuum tube|vacuum-tube]] [[radio receiver]]s as a [[beat frequency oscillator]] (BFO) to make [[continuous wave]] [[radiotelegraphy]] ([[Morse code]]) signals audible.