Microphones

• "Acoustic Device", Henry C Egerton, US Patent 1383700. 1921. carbon mic as detector of submarine vessels.
• "Acoustic Switch", A. R. Eastman, US Patent 2466881. 1949. not far from the Victorian Synthesizer of John Bowers.
• "Sound Pickup and reproducing Apparatus", J MacDonell, US Patent 2666650,1954. an optical microphone and recorder.
• "Apparatus for Reverberating Sounds", W Rehde, US Patent 3152660. 1964. in-mic reverb.

Pickups using magnetism

• "Piano", lloyd Loar, US Patent 1821978. 1931
• "Musical Instrument", lloyd Loar, US Patent 1995316. 1935
• "Stringed Musical Instrument", Lloyd Loar, US Patent 2020557. 1935
• "Stringed Musical Instrument", Lloyd Loar, US Patent 2025875. 1935
• "Electrical Musical instrument" Guy Hart, 2087106, 1937.
• "Electrical Musical instrument" Guy Hart, 2089171,1937.the "frying pan" pickup for Gibson Co.
• "Musical Instrument", F. H. Kislingbury, 2171430, 1939. the Violectric for the Dopyera Co.
• "Combination Bridge and Pickup Assembly", L Fender, 2573254, 1951.
• "Pick-ups for Guitars and Coupling Circuits Therefore", J. O. Burns, US Patent 3249677. 1966
• "String Instrument Vibration Initiator and Sustainer", Gregory S Heet, US Patent 4075921. 1978. The first of two e-bow patents.
• "Hand Held Musical String Vibration Initiator and Sustainer", Gregory S Heet, US Patent D248122. 1978. the second of two e-bow patents.
• "Apparatus for Playing Musical Instruments", Godley and Creme, US Patent 3882754. 1975. the Gizmotron.
• "Coil-less Magnetic Pickup for Stringent [sic] Instrument", Robert M Iodice, US Patent 4182213. 1980. uses Hall-effect.
• "Transducer for a Stringed Musical Instrument", Christopher Kinman, US Patent 5668520. 1997
• "Noise-sensing Bobbin-coil Assembly for Amplified Musical Stringed Instrument Pickups", Christopher Kinman, US Patent 7022909. 2006
• "Strap Amplifier", Peter Bellak, US Patent 7060889, 2006

Pickups using optical methods

• "Stringed Musical Instrument with Optoelectronic Pickup Sound Amplifer", Dennis Ferber, 3733953, 1973. employs LED-phototransistor pairs.
• "Optoelectronic Sound Amplifier System for Musical Instruments", J. J. Ryeczeck, 4028977, 1977. "unworkable" system detecting the light reflected from the vibrating surface of an acoustic instrument.
• "Optical Pickup for use with a Stringed Musical Instrument", Bing McCoy, 4688460, 1987