Hugh Hetherington Hearing Aid Museum
Hugh Hetherington Hearing Aid Museum

The 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.

 

Transistor (Body) Hearing Aids

Audivox Model 77 "Extra" Transistor (Body) Hearing Aid

The Audivox Model 77 "Extra" transistor body hearing aid was made by Audivox, Inc. of Boston, MA in 1957.

This hearing aid had 5 transistors and utilized a push-pull amplifier circuit. It measured 2 15/16" x 1⅞" x ⅝" (7.4 x 4.7 x 1.6 cm) and weighed 3.1 oz (88 g) without batteries.

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Front view of the Audivox Model 77 "Extra" transistor body hearing aid showing its chrome front. Note the wire pocket clip.

 

 

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Close-up of the upper front of the Audivox Model 77 "Extra" transistor body hearing aid showing the microphone grill (hole in center) set in an attractive graphic design.

 

 

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Top view of the Audivox Model 77 "Extra" transistor body hearing aid showing the  the on-off/volume control wheel (left), the T (t-coil) M (microphone) switch (center) and the 3-position tone control wheel (right) (see below for description).

 

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Close-up of the top left corner of the Audivox Model 77 "Extra" transistor body hearing aid showing the 3-position tone control—L (low-frequency emphasis), N (normal tone) and H (high-frequency emphasis).

 

 

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Rear view of the Audivox Model 77 "Extra" transistor body hearing aid showing the battery door on the lower half of the back. The battery door swung up from the bottom.

 

 

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Bottom view of the Audivox Model 77 "Extra" transistor body hearing aid showing the recessed thumbnail slot (center) to pull open the battery compartment door.

 

 

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View of the inside of the battery compartment lid of the Audivox Model 77 "Extra" transistor body hearing aid battery compartment showing the warning "Important" and "Remove battery when not in continuous use". Otherwise, the batteries tended to corrode in place and destroy the battery compartment.
 

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View of the battery compartment of the Audivox Model 77 "Extra" transistor body hearing aid with the battery compartment door opened. It swung up from the bottom.

The left side shows the serial number (R4676) in white numbers. Below that is the manufacturer's information (Audivox, Boston, Mass, USA) and near the bottom, the model number (Model 77).

Above the model number is a two position (red or blue dot) red screw of unknown function.

On the right note the twin battery slots. This was a higher-powered aid and took not one, but two, batteries.

Also note the black vinyl plastic "tab" that went under the batteries to make it easy to remove them.

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View of the Audivox Model 77 "Extra" transistor body hearing aid battery compartment showing how pulling up on the black vinyl tab (right side) dislodged the batteries so you could easily replace them.

 

 

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View of the battery compartment of the Audivox Model 77 "Extra" transistor body hearing aid showing the two Type "N" or 401 batteries in place.

This aid used two 1.4 mercury batteries such as these Rayovac RP-401 batteries.

 

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Lower right side view of the Audivox Model 77 "Extra" transistor body hearing aid showing the two-holed jack for the receiver cord and the plug on the end of the receiver cord. Both holes and prongs were the same size so it could be plugged in either way.


 

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Right side view of the Audivox Model 77 "Extra" transistor body hearing aid showing the receiver cord plugged into the body.

Note that the plug should be plugged in as shown so the receiver cord would not have to have a sharp bend in it when used in a pocket.

 

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Front view of the Audivox Model 77 "Extra" transistor body hearing aid receiver showing the the part number—020 (top) and ?2-7 (bottom).  The ear mold snapped onto the nubbin in the center.
 

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Close-up of the back of the Audivox Model 77 "Extra" transistor body hearing aid receiver. The receiver cord is plugged in (right).

 

 

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Close-up view of the Audivox Model 77 "Extra" transistor body hearing aid receiver and ear mold unsnapped.

 

 

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Side view of the Audivox Model 77 "Extra" transistor body hearing aid receiver showing the clear plastic ear mold (left) snapped to the receiver (right).

 

 

 

 

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