Oberlin Smith published a description of magnetic recording in Electrical World, Sep. 8, 1888, based on his visit to Edison's lab in 1878, using an electromagnet with a string covered with iron filings. He may have built a working model but no device has survived.Above is the "original drawing of Oberlin Smith (1840-1926) published in the Electrcial World of 8.9.1888. The spoken words are transformed by the telephone A into an electrical sound signal and are recorded in the form of magnetization patterns on the sound carrier C, passing through the recording head B.
F = battery, E = take up reel, D = supply reel, J = reel brake." (from Heinz Ritter, 1988)
Valdemar Poulsen in 1894 discovered the magnetic recording principle while working as a mechanic in the Copenhagen Telegraph Company. In 1898 he patented the telegraphone, the first successful magnetic recording device.
Valdemar Poulsen in Denmark would succeed in 1898 where Smith had failed. He built and patented the first working magnetic recorder called the Telegraphone with wire wrapped around a drum and a recording/playback head that moved by a screw thread on top. Poulsen had become a telephone engineer at the Copenhagen Telephone Company in 1893 and began to experiment with magnetism to record telephone messages.
By 1899 he filed U.S. patent 661,619 for a vertical wire-covered cylinder, and in 1900 demonstrated improved drum and horizontal wire cylinder models at the 1900 Paris Exhibition. While making these improved models, Poulsen and his partner Peder O. Pedersen discovered the application of a direct current to the recording head, called dc bias, improved the sound quality on a steel tape version of the Telegraphone. At the Paris fair, Poulsen recorded the voice of Emperor Franz Joseph, today preserved in the Danish Museum of Science and Technology as the oldest magnetic sound recording in existence.
Poulsen stopped his work on magnetic recording and turned to radio after 1902, and only a small number of his machines were made in Denmark and Germany. The American Telegraphone Company acquired the patent rights in 1905 and made dictating machines, selling 50 to the Du Pont Company. However, the signal remained weak without amplification and the wire spools became twisted and were unreliable. The wax cylinder phonographs of the rival Ediphone and Dictaphone companies were cheaper and more reliable. By 1918, the company went into receivership and stopped manufacturing after 1924.
"In 1930 the Allgemeine Elektrizitatsgesellschaft [AEG] in Berlin decided to start the development of a magnetophone machine, based on the Pfleumer principle. 2 years later there was an agreement of collaboration with BASF, Ludwigshafen: AEG developed the system, BASF an appropriate sound carrier. This collaboration did not come by accident. On the contrary, BASF had the knowledge necessary for the development of magnetic tape.
Here since 1925, carbonyl iron powder in the finest particles had been produced for induction coils in telephone cables and for mass cores in the high frequency technique. In addition, experience had been gathered in the manufacture of enamel paint by milling and dispersing of dyestuffs with cellulose acetate and solvents. At the same time the development of plastics had started for the production of foils and fibres. Thanks to this rich experience in 1934 BASF was able to ship the first 50,000 meters of magnetic tape. The tape consisted of a foil of cellulose acetate as carrier material, coated with a lacquer of iron oxide as magnetic pigment and cellulose acetate as binder.
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