• March 22, 1840: Oberlin Smith born in Cincinnati, Ohio, USA
• 1862 Valdemar Poulsen born
• February 14, 1876: Alexander Graham Bell receives U.S. Patent 174,465 for the telephone
• End of 1877 / Beginning 1878: Smith learns of the invention of magnetic sound recording by T. A. Edison: "... in an early acquaintance with Mr. Edison he showed me his recently invented phonograph ... I presently acquired one of these phonographs ..."
• April 5, 1878: Article in the "Bridgeton Chronicle": Two Great Inventions on the inventions of the telephone and the phonograph: "A combination of the two great inventions may, in time, make it a common experience for one to send a message by Telephone and preserve it by Phonograph ..."
• about April 30, 1878: Smith invents improvements for the Edison phonograph, without initially getting away from magnetic sound recording.
• between April 30, and September 23, 1878: Smith outlines the possibility of magnetic sound recording on a magnetizable medium of tempered steel which is magnetized by a short helix. Playback by means of induction. Advantages: cheap, simple, "delicacy".
• September 23, 1878: Smith files two memoranda with the County Clerk of Cumberland County (improvements in mechanical sound recording and invention of magnetic sound recording).
• October 4, 1878: Oberlin Smith draws up a "Caveat" for the United States Patent Office (the US $10) to a certain extent as a preliminary stage for a patent application on an Electric Phonograph or Recording Telephone, which deals exclusively with magnetic sound recording. It is more precise and more extensive than the memorandum of September 23, 1878; the technical content is beyond the publication in The Electrical World of 1888.
• November 26, 1878: Smith orders from T.A. Edison "a button of mercury-impregnated carbon, similar you use in your carbon telephone" - December 6, 1878: Smith places a renewed order with Edison for one (or two) "carbon buttons" - Dec. 13, 1878: Smith confirms receipt of the two "buttons", Price: US$ 2.
• 1878/1888: Development of the spinning machine: pieces of steel wire woven into cotton cords
• 1887/1888: Fresh activities in mechanical sound recording (Ch. S. Tainter and Emile Berliner)
• September 8, 1888: "Some Possible Forms of Phonograph" published in The Electrical World
• September 29, 1888: Reader's letter from Smith in "The Electrical World". Smith explains the elongatedly drawn coil as an error in illustration and refers to his experiments with a single-pole transducer.
• 1898: Application of the first Poulsen patents
• 1900: Poulsen presents the phonograph at the international exhibition in Paris.
• June 28, 1900: the Examiner of the US Patent Office cites "Some Possible Forms of Phonograph" in opposition to Patent Application 661,619.
• July 11, 1900: Poulsen's attorney W. A. Rosenbaum contests the relevance of "Some Possible Forms of Phonograph" in a reply to the US Patent Office.
• November 5, 1900: Smith writes to Mr. Chas. A. Lieb, New York, to register his interests in the further development of the telephonograph.
• November 9, 1900: Oberlin Smith turns to the US Patent Office after having been informed of the Poulsen machine by reading about it in newspapers.
• January 29, 1901: Smith orders a copy of his Caveat of October 4, 1878 from the US Patent Office.
• September 27, 1903: In a fire at Oberlin Smith's Ferracute factory, his experimental magnetic recording equipment is destroyed.
• January 15, 1907: US Patent 841,387 for the invention of the vacuum tube by Lee de Forest
• December 10, 1907: DC-biasing patented: US Patent 873,083, Inventors: Pedersen and Poulsen
• December 23, 1908: The County Clerk of Cumberland County confirms the existence of the two memoranda of September 23, 1878.
• December 20, 1910: German Patent 249,142 (R. von Lieben, E. Reisz and S. Strauss): Vacuum tube in amplifier circuit
• October 1911: Smith writes his detailed report on his work on magnetic sound to the Franklin Institute
• May 21, 1913: Before the Franklin Institute in Philadelphia Emile Berliner describes Oberlin Smith as the first to propose magnetic recording. Berliner leaves the question open as to whether Poulsen depended on Smith.
• March 26, 1921: US Patent 1,640,881 for the invention of high-frequency biasing (here only for increasing sensitivity) by Wendell L. Carlson and Glenn W. Carpenter, Washington, D.C.
• 1921: Oberlin Smith designs the "Autofono", a fully automatic record changer
• 1924/26: Smith receives two patents for his record changer, the second three weeks before his death.
• July 18, 1926: Oberlin Smith dies.
• 1928: Fritz Pfleumer develops magnetic tape (in the modern sense)
• 1930/1932: Development of the Marconi-Stille magnetic steel tape recorder in England, the "Stahlton-Bandmaschine" by Dr. S. J. Begun at C. Lorenz in Germany
• 1932/33: Beginning of cooperation on the "Magnetophon": AEG Berlin builds equipment, BASF Ludwigshafen produces the "Magnetophon tape"
• 1934: Oberlin Smith's home is destroyed by fire
• 1935: Presentation of the "Magnetophon" at the Berlin Radio Exhibition with sensational success
• 1938: German radio puts the "Magnetophon" into operational service; Walter Weber works on quality improvements.
• 1940, on the 100th anniversary of Oberlin Smith's birth: In experiments, Dr. Walter Weber accidentally discovers quality improvement by high-frequency biasing and introduces it in radio broadcasting
• 1944: Stereo recordings of the Berlin Reichs-Rundfunk-Gesellschaft (German Radio Broadcasting Corporation) on Magnetophon taperecorder.
• 1942: Valdemar Poulsen dies.

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