Bosch Model 55F Transistor Eyeglass Hearing Aid
The Bosch Model 55F eyeglass hearing aid (also called the Star 55F) was manufactured by
Robert Bosch Elektronik GmbH of Berlin, Germany in 1981.
It was rather unusual for its time in that it could be configured as
a hearing aid with all the electronics in one temple-piece, or it could
be configured so the microphone was contained in the opposite
temple-piece to reduce feedback when used in its high-powered settings.
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Front view of the Bosch Model 55F eyeglass hearing aid. The hearing aid
electronics are in the left temple-piece and the microphone is in the
right temple-piece.
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Front view of the Bosch Model 55F eyeglass hearing aid with the temple
pieces folded for storage.
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Underside view of the left temple-piece of the Bosch Model 55F eyeglass hearing aid showing the serial number—very
faintly stamped into the case below the model no. (55F). The serial
number is very difficult to read but appears to be "931...08".
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Bottom view of the left temple piece of the Bosch Model 55F eyeglass
hearing aid showing the various controls.
To the left of the model number (55F) is a recessed
screwdriver-accessible control—presumably for adjusting maximum gain.
Next to it is the 1-4 position volume control; the tone control (TC)
with "high" (H) to the left and "normal" "N" to the right; the
3-position "off" (O), "t-coil" (T) and "microphone" (M) switch shown in
the off position; the "dummy" (in this case) domed microphone grill; and
the plug for the wire coming from the other temple-piece.
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Close-up view of the bottom front of the left temple piece of the Bosch Model
55F eyeglass hearing aid showing the above-mentioned last four items in
greater detail. Note that in this particular model, there is no
microphone below the microphone grill as it uses the microphone built
into the opposite temple-piece.
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Close-up bottom view of the electronics module in the left temple piece
of the Bosch Model 55F eyeglass hearing aid showing the various
components including the volume control wheel (center).
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Close-up top view of the electronics module in the left temple piece of
the Bosch Model 55F eyeglass hearing aid showing the various components
including the volume control wheel (left of center).
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View of the bottom of the left temple piece of the Bosch Model 55F
eyeglass hearing aid showing the thick temple piece with the ear mold
attached to the nubbin.
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Inside rear view of the electronics module of the left temple piece of the Bosch Model 55F eyeglass
hearing aid
showing the receiver—the transducer that produces the sound (right) and
below it the nubbin with the ear mold tube slid onto it.
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Inside top view of the left temple-piece of the Bosch Model 55F eyeglass
hearing aid showing the space reserved for the microphone IF this aid
was to be configured so it only used one temple-piece. (Note the
microphone grill holes at the back. Also, note that the microphone shown
below in the opposite temple-piece would fit exactly into this space.)
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Bottom view of the right temple piece of the Bosch Model 55F eyeglass
hearing aid
showing the microphone port (left). The dome-shaped microphone grill is
missing (but it would look identical to the microphone grill on the left
temple-piece). The name "Bosch" is to the right.
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Bottom inside view of the right temple piece of the Bosch Model 55F
eyeglass hearing aid showing the cream-colored rectangular microphone
directly above the microphone port.
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Top inside view of the right temple piece of the Bosch Model 55F
eyeglass hearing aid showing the cream-colored rectangular microphone
(left) and how it was wired to the mounting post (right). To the extreme
right is the wire that runs to the left temple-piece.
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Close-up view of the hinge of the left temple-piece of the Bosch
Model 55F eyeglass hearing aid showing the wire from the microphone that crossed over from
the right temple-piece.
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Close up view of the nose bridge of the glasses of the Bosch Model 55F
eyeglass hearing aid showing the wire going from the right to the left
temple-piece.
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Top view of the glasses of the Bosch Model 55F eyeglass hearing aid
showing the wire (thin black line) above the lens going from the right
temple-piece to the left one.
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Rear view of the Bosch Model 55F eyeglass hearing aid.
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Bottom view of the end of the left temple piece of the Bosch Model 55F
eyeglass hearing aid showing the name (Bosch) and the location where
this hearing aid was made (Germany). Actually, both temple-pieces have
the name on them. Both temple-pieces are identical inside so the
electronics modules could be mounted in either of them depending on
whether you needed a hearing aid in your left or right ear.
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Close-up view of the tip of the left temple piece of the Bosch Model 55F
eyeglass hearing aid showing the battery compartment door in the open
position. The battery door swung up from the bottom. |
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Close-up view of the tip of the left temple piece of the Bosch Model
55F eyeglass hearing aid showing the battery in the battery compartment. This hearing aid took a
675 mercury battery.
Note that the right temple-piece had a similar "dummy" compartment
for carrying a spare battery.
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