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Ben H. Tongue's technical talk about Crystal Radio Section 1: Original technical Articles relating to crystal radio design may be found here. Many have application to areas other than crystal radios such as diode detector loss, measurement of diode SPICE parameters, inductor and capacitor Q, headphone impedance and loss measurement, audio transformer loss and measurement, along with many tutorial notes. Section 2: The Edison Company entered the radio field early in 1929 in an attempt to reverse a drastic downturn in their home entertainment phonograph business. About three-quarters of a year later, because of increasing losses, they closed the phonograph part of their home entertainment business to concentrate on radios. Unfortunately, the radio effort did not live up to expectations, and was closed at the end of 1930. This Section includes many documents copied directly from the Edison National Historic Site: Minutes of internal meetings related to radio design and manufacturing, User and Service data on Edison Radios, copies of advertisements, and Corporate Annual reports of the Radio Division (Splitdorf Radio Company). Section 3: TRF Radio receivers for the home reached their peak of development in the 1928-1929 time frame. Technical performance data and the IRE Measurement Standard as of 1929 can be found in this Section. Section 4: Interesting Information about antique Hearing Aids includes user manuals for Acousticon carbon-type electric hearing aids from about 1926 and articles from Radio-Craft magazine of Oct 1938 about Hi-Fi hearing aids and hearing aid testing methods. Section 5: About Blonder-Tongue Labs and Ben H. Tongue Section 6: Links related to crystal set design and construction, component suppliers, a Museum collection of antique wireless and scientific instruments, Electronic Engineering resources, some Clubs and more. Location of the most recent changes: Part 13 was added to Article #0 in Section 1: Comments on audio distortion in diode detectors - 11/04/07. Part 5 of Article #0 in Section 1 was augmented: Explanation of why, in a diode detector, and by how much, the RF input resistance and audio output resistances change as a function of input signal power. - 11/06/07. A new Section 4 on antique Hearing Aids has been added. - 11/16/07. A new Part 4 has been added to Article 29 in Section 1 showing flux density patterns in a ferrite rod having a central air gap - 11/02/07. "One final equation" (Eq 8) has been added near the end of Article #15A, in Section 1. It should be of interest to all concerned with getting that last bit of weak-signal sensitivity out of a diode detector. A new Part 4 has been added to Article #5 in Section 1 showing loss measurements on a modified UltiMatch audio impedance matching device, including measurements of input resistance. - 02/17/08. New Part 4 in Article #5, Section 1 now includes a description of an adjustable audio impedance matching device similar to Steve Bringhurst's UltiMatch. I's called a BT-UltiMatch - 03/30/08. Copyright Notice: This page published: 10/04/2006; Revised 03/30/2008 |