Electrical Products Manufacturing Company, 69 Sprague St, Providence, RI was established in 1919. President was Frank E Dyson, Vice President was Thomas P Giblin, Secretary and general manager was H A McAvoy and Treasurer was Charles Eddy. 1 Frank E Dyson was also formed the Commercial Radio Company of America with Thomas P Giblin, and Ratcliffe G E Hicks 5.
In 1920 Electrical Products Manufacturing Company had radio station 1XF transmitting at both 300 and 600 wavelength. 3
In 1922, Dymac leased large floor space at 24 Fountain St, in Providence in addition to their regular plant. 2
The 1923 Journal of the A.I.E.E. (American Institute of Electrical Engineers) lists Mr Omar E Cote as the Chief Engineer. 4 and their address as 69 Sprague Street 10.
In 1924 Electrical Products Manufacturing Company hired the Lachar-Horton Company to direct advertising for the firm. 11
The 1926 Providence Directory still lists Frank E Dyson president but now H A McAvoy in the treasurer and Ratcliffe G E Hicks, Secratary. The company is still at 69 Sprague Street with 150 employees. 6 The chief engineer for the Electrical Products Manufacturing Company (Dymac) in 1926 was Charles V Logwood. Mr Logwood was the co-inventor with Dr Lee Deforest of the audion tube, which made broadcasting possible. He alone discoverd the Audion amplifier which came into use in 1912. He also directed the installation of the first three broadcast stations in the United States.
I know from their ads they made headphones, speakers and a 5 tube set called the selecto-five 12. There is also an ad for a six-tube receiver kit.
In the 1927 Providence Directory there is a listing for George W Hamilton as tresurer 7.
In 1928 the factory was turning out 116 coil types for the Signal Engineering Corporation of the U S Government. The factory did all the work for the radio department of the United States 13.
We find Electical Products Manufacutring Company still listed at 69 Sprague Street in 1929 8, and 1932 9 and then again in 1932 with the addition of George W Hamilton as the receiver 9.
Duo-Lateral Type Inductances
1 EMF Electrical Year Book, Volume 1, 1921
2 Electrical World, Volume 79, 1922
3 Commercial and Government Radio Stations of the U.S., 1920
4 1923 A.I.E.E. Journal
5 Acts And Resolves Passed By The General Assembly Of The State Of Rhode Island And Providence Plantations, 1920
6 Providence Directory, 1926
7 Providence Directory, 1927
8 Providence Directory, 1929
9 Providence Directory, 1932
10 Providence Directory, 1923
11 Advertising and Selling Fortnightly, November 1924
12 Radio Call Book, Fall, 1923
13 Asbury Park Press September 28, 1925