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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General Info

Non-Electric

Carbon

Vacuum Tube

Transistor (Body)

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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.

Hearing Aid Batteries

520 Mercury Hearing Aid Battery

This No. 520 1.4 volt mercury hearing aid battery was used in transistor hearing aids in the mid-1950s.

The No. 520 mercury battery weighed about 1 gram, and measured ¼" high by 7/16" in diameter.

Mercury batteries are no longer sold today because of the large quantities of mercury in them and the consequent environmental concerns.

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The reverse side of the No. 520 mercury battery.

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The No. 520 battery (left) compared in size to a Canadian quarter.

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