Friday, August 24, 2018

The patents of Otarion E4 Hearing Aid


At your risk. Protect your hearing.


These are only some considerations on possibly using it as a studio microphone preamplifier.


In includes just 3 subminiature direct heater? electron tubes and so few resistors, capacitors inside for many 10th dBs of gain. All in a space less than a transistor radio. The designers were clearly so many years ahead of their time.


It can be opened by removing 2 screws.


The capacitors are relatively small.


There is an audio transformer or inductor possibly for output. Schematic information is welcome at the comments section of this post.


A aluminum large diaphragm crystal microphone.


It should be a marvel of low noise since it is electron tube and the plates or anodes are operated at low electric potential or voltage. Small electric field. Microamperes of anode current can sound really nice and low noise. Much of the unwanted bass heaviness is removed. See previous posts.


Inside there is a notice: licensed by Western Electric company under U.S. Patents of American Telephone and Telegraph company... manufactured under the following patents with the following patents:


US2280304


US2280305


US2284063


US2284451


US2290816


US2296454


US2418410


US2434211


Canedian Patent , 1943


Other patents pending.


If anyone knows could you please post the electron tubes used. The opened example has only one and the type number is unreadable. It should be made by Raytheon.


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