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Armstrong's
Regerative
Circuit 

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A Notable Wireless Advance: Armstrong's Regenerative Circuit

This is a report David Sarnoff filed after testing Edwin Armstrong's breakthrough device, the regenative circuit, at Camp Evans when it was Marconi Belmar Station.  This was a major advance in radio/wireless technology.  Although the circuit was not invented at Camp Evans this test is spoken of in many oral histories, radio history documentary videos, and books.  David Sarnoff would become a vice President in the Marconi Wireless Telegraphy Company of America, then President of RCA, and is considered the driving force behind the developement of color TV.  Edwin Armstrong would make many more excellent advances in radio, not least of which was the FM system.

A Notable Wireless Advance
Armstrong's Regenerative Circuit
Source: Looking Ahead – The Papers of David Sarnoff, 1968
Courtesy of: Historical Electronics Museum, Md.

Memorandum to F. M. Sammis, Chief Engineer Marconi Wireless Telegraph Company of America, February 2, 1914

On January 30th, I met Mr. E. H. Armstrong, Professor Morecroft, and Mr. Roy Weagant, with whom I proceeded to our high-power station at Belmar, N.J., to test Mr. Armstrong's receiving system.

Two aerials were erected, one about 1,6oo feet long and the other the entire length of the masts erected at Belmar.

Signals were heard from Clifden, Ireland, at about 4 P.m. ( New York time), and from this time until we finished experimenting, which was about 5 A.M. (New York time), January 31st, no appreci-able variation of intensity of Clifden signals was noticeable . . . .

There was no difficulty in reading Clifden signals when the tele-phone receivers were on the table, and I stood about i z feet away from the telephone. With a loudspeaking telephone connected to the receiver, signals could be read in the adjoining room.

….Speaking relatively of received signals means, of course, very little, since the human ear is not to be depended upon, but an idea of the difference may be obtained when it is stated that signals from Clifden on Armstrong's receiver could be read with ease with telephones on the table when signals on our receiver were barely readable with the telephones on the ears .

. . . At about midnight (New York time), I heard "HU"-Poulsen station at Honolulu-trying to work with the Poulsen sta-tion at San Francisco . . . . Signals received from Honolulu were sufficiently strong to be read with the telephones on the table.

At 1:25 A.M., January 31st, I heard the Telefunken station at Nauen, Germany, calling "P.O.Z." . . . . The text of the message and the beginnings and endings signified very clearly that it was the Nauen station transmitting. The signals from the Nauen station were very good and strong . . . .

I would state that the results obtained with Mr. Armstrong's receiver are sufficiently convincing to warrant our most careful investigation of this device.
Page updated January 3, 2004   page created July 4, 1999

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