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Edwin H. Armstrong Papers Edwin H. Armstrong papers 1981.4 Finding aid prepared by Sarah Leu and Jack McCarthy through the Historical Society of Pennsylvania's Hidden Collections Initiative for Pennsylvania Small Archival Repositories. Last updated on September 12, 2016. The Historical and Interpretive Collections of The Franklin Institute Edwin H. Armstrong papers Table of Contents Summary Information....................................................................................................................................3 Biography/History..........................................................................................................................................4 Scope and Contents..................................................................................................................................... 10 Administrative Information......................................................................................................................... 11 Related Materials......................................................................................................................................... 12 Controlled Access Headings........................................................................................................................12 - Page 2 - Edwin H. Armstrong papers Summary Information Repository The Historical and Interpretive Collections of The Franklin Institute Creator Armstrong, Edwin H. (Edwin Howard), 1890-1954 Title Edwin H. Armstrong papers Call number 1981.4 Date [inclusive] 1909-1956 Extent 4.35 linear feet Language English Language of Materials NoteSome materials are in French. Abstract Edwin H. Armstrong (1890-1954) was an American electrical engineer and inventor, best known for inventing the regenerative circuit, the super- regenerative circuit, the superheterodyne receiver, and FM (frequency modulation) radio. He spent much of his life battling in court over his patent rights, primarily with Lee De Forest and Radio Corporation of America, and took his own life in 1954. Edwin H. Armstrong papers, 1909-1956, consist of photographs, lecture notes, letters, certificates, published materials, programs and ephemera, materials from his memorial service, and other documents. - Page 3 - Edwin H. Armstrong papers Biography/History Edwin H. Armstrong (1890-1954) was an American electrical engineer and inventor, best known for inventing the regenerative circuit, the super-regenerative circuit, the superheterodyne receiver, and FM (frequency modulation) radio. He spent much of his life battling in court over his patent rights, primarily with Lee De Forest and Radio Corporation of America, and took his own life in 1954. "Edwin Howard Armstrong was born on December 18, 1890, in the Chelsea District of Manhattan [New York, NY]. He was the first child of John and Emily (Smith) Armstrong. John worked as Vice President of the American branch of Oxford Press, while Emily, a graduate of Hunter College, taught in the New York City public schools. Prior to moving out of Manhattan, Edwin gained two younger sisters, Ethel and Edith. In 1902, the Armstrong family moved north, to 1032 Warburton Avenue, in Yonkers, New York. "In 1905, Armstrong entered high school. He already sought to emulate Marconi, the Italian inventor responsible for a system of wireless telegraphy. He began to tinker with the telegraph with companions in his neighborhood who were also taken with the invention. Many of these childhood companions would become lasting friends for the balance of [Armstrong's] life. Thomas Styles lived down the block in Yonkers; Randy Runyon was located about a mile away, and William Russell was in the adjacent town of Hastings-on-Hudson. [Armstrong's] uncle, Frank Smith, introduced him to Charles R. Underhill, an engineer and inventor for the American Telegraph Company. He furnished Armstrong with experimental apparatus, and more importantly, a constant mentor. [Armstrong] would join Underhill frequently after school for years, where they would discuss wireless phenomena. "On June 24, 1909, Armstrong graduated from high school. The following September, he entered Columbia University's Department of Electrical Engineering. Armstrong was constantly in the laboratory, conducting endless experiments. Some professors thought the young student needed discipline, he did not...maintain records of his experiments. But several instructors defended Armstrong, fostering his need for freedom to investigate. [Armstrong] distrusted mathematics as the essential proof of phenomena of the physical world and refused to accept the findings of experts. He continued his experiments both at the Columbia lab and in his attic at home. He was determined to find a method that would strengthen the wireless signal. "While in his junior year, Armstrong came under the influence of Professor Michael I. Pupin. Pupin was one of the founders of the Columbia University Department of Electrical Engineering, and head of the Marcellus Hartley Research Laboratory. Pupin believed in rigorous scientific experiments, understanding that theory cannot replace results. A successful inventor himself, he soon took notice of Armstrong. "In 1912, Armstrong joined the Radio Club of America, which his close friends from Yonkers had all joined. The Club, originally called the Junior Wireless Club Ltd., had been organized in 1909, with Reginald A. Fessenden as the advisor. Fessenden had invented and patented the heterodyne principle in 1902. It was an amateur club that would eventually have a large impact on the development of radio and more specifically, Armstrong's career. The Regenerative Circuit - Page 4 - Edwin H. Armstrong papers "In 1906, Lee de Forest created the "audion", an early vacuum tube, by adding a wire grid to the Edison- Fleming diode. Subsequently, in 1912, he accidentally connected the output circuit of one audion to its own input circuit and obtained a loud howling sound, which he later identified as regeneration. Instead of attempting to understand the hissing or howling sound, he tried to abolish it. "When Armstrong began experimenting with the audion, he took numerous measurements in order to ascertain how this tube functioned, eventually devising a circuit that would operate as a powerful amplifier of incoming radio waves. By the winter of 1912, he had discovered that if part of the plate's output circuit was fed back to the grid in a controlled manner, the incoming signals were remarkably strengthened. In addition, he discovered that when feedback was increased sufficiently the circuit could be used as a transmitter by generating high frequency oscillations, a required element for radio communications. He mentioned his idea to instructors at Columbia University, who advised him to contact William Davis, a patent attorney who had secured patents for many of them. Lacking the necessary funds to file, his uncle advised him to prepare a sketch and have it notarized. He did just that, providing him with a record date of January 31, 1913. "Armstrong's regenerative circuit led to a nearly twenty year legal battle over patent rights. While the controversy is best known to have been between Armstrong and de Forest, there were actually two other individuals who claimed rights to this invention-- Irving Langmuir and Alexander Meissner. "In October 1913, Armstrong, along with another inventor, Irving Langmuir of General Electric, filed patent applications disclosing the principle of radio-frequency regeneration and claimed the arrangement of tuned radio frequency circuits, which is characteristic of the invention. Armstrong's patent was issued on October 6, 1914. This patent disclosed the circuit arrangement in its non-oscillating stage, that of an improved receiver of wireless signals. By now his patent attorney, William Davis, recommended he incorporate the transmitting ability into the same patent. Armstrong refused and the regenerative circuits oscillating capacity was disclosed in a separate patent application, filed December 18, 1913. "A German inventor, Alexander Meissner, filed a United States Patent application on the regenerative circuit on March 16, 1914. Four days later, Lee de Forest filed an application for his "ultra-audion". In De Forest's original claims, he considered his device a detector, not an amplifier (transmitter). "In November 1913, de Forest delivered a paper to the Institute of Radio Engineers (IRE) on the subject of "The audion, detector and amplifier". He gave an explanation of the action of the audion with regard to circuit change. He made no mention of feedback and this presentation served to reinforce the fact that he did not understand the audion qualities or how it functioned. It was not until after Armstrong's paper "Some Recent Developments in the audion Receiver", was delivered to the IRE in New York on March 3, 1915, and published in September, that de Forest changed his patent disclosure. De Forest filed for patent with oscillating features in September 1915 and was later issued a second patent, claiming a date of invention prior to March 1913, disclosing specifics of regeneration. "This was the patent that the United States Supreme Court would, on May 21, 1934, decide to sustain in favor of de Forest. The decision of the Supreme Court was the thirteenth pronouncement by a judicial or administrative tribunal with regard to the question of priority between Armstrong and de Forest. These two men fought each other in the courts both as individuals and through the corporations (Westinghouse Electric
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