Tonewheel
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A tonewheel or tone wheel is a simple electromechanical apparatus used for generating electric musical notes in electromechanical organ instruments such as the Hammond organ and in telephony to genera
Goldschmidt tone wheel (1910), used as an early beat frequency oscillator
Rheotome-cylinders and electric-brushes used on Telharmonium (1896)
Telharmonium
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The Telharmonium was an early electrical organ, developed by Thaddeus Cahill c. 1896 and patented in 1897. The electrical signal from the Telharmonium was transmitted over wires; it was heard on the r
Tonewheel
…instruments such as the 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. It was reinvented around 1910 by Rudolph Goldschmidt for use in pre–vacuum-tube radio receivers as a beat frequency…
Telharmonium console by Thaddeus Cahill, 1897
The workshop console of the telharmonium during its development at the New England Electric Music Company's Cabot Street Music Plant, in Holyoke, 1906.