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On-line Hearing Aid Museum |
Hearing Aids of all types—Ear
Trumpets, Carbon Hearing Aids, Vacuum Tube Hearing Aids,
Transistor Hearing Aids, Body Hearing Aids, Eyeglass Hearing
Aids and much more! |
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Click on the "General
Information" button (top button above) for an overview and general
information on this category of hearing aid. |
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Hybrid Vacuum Tube/Transistor Hearing Aids |
Fortiphone Model 40 Hybrid Hearing Aid
The Fortiphone model 40 hybrid hearing aid appears
to be a late comer in hybrid hearing aids. It was manufactured by
Fortiphone Ltd. of London. It is not known exactly when it first appeared, but
it could have been as late as 1955. It used two vacuum
tubes and one transistor. The Fortiphone model 40 used the same case as the Fortiphone model
23 vacuum tube hearing aid.
This hearing aid weighed 4 oz. with batteries, and
measured 3⅛" x 1⅞" x ¾". |
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Click picture for larger view |
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The inside of the battery compartment showing the model number.
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The batteries shown installed in the battery compartment. The
Fortiphone 40 was powered by a 30 volt "B" battery type 506E
(bottom), and a 1.4 volt RM-1 mercury "A" battery (middle
right).
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Click picture for larger view |
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