This Section contains 29 original Technical Articles relating to Crystal Radio Set Design. Many have application to areas other than crystal radios such as diode detector power loss and the 'linear to square-law crossover point' (LSLCP), measurement of diode SPICE parameters, ferrite inductor and variable capacitor Q, impedance matching, headphone impedance and transduction loss measurement, audio transformer loss and measurement, along with many tutorial notes.

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 that part of their business to concentrate on radios.  Unfortunately, the radio effort did not live up to expectations, and was closed at the end of 1930.  Many of the documents shown here were copied directly from the originals in 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).

TRF Radio Receivers for the home reached their peak of development in the 1928-1929 time frame. Technical performance data of many of these receivers, as well as the IRE Receiver Measurement Standard as of 1929, may be found in this Section.

This Section includes Information about Antique Hearing Aids such as copies of 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.

Here is some information about Blonder-Tongue Labs and Ben H. Tongue

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