Sonotone X42 Hearing Aid Battery
This is a 3-volt Sonotone X42 battery that fit a number of carbon hearing aids in the 1930s
and 1940s. It weighed 10½ oz., and measured 4⅛"
by 2¼" by 1⅛". As you can faintly see on the front, it is
date-stamped Jan. 11, 1945.
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Top view of the Sonotone X42 battery showing the 3-hole socket. Only the 1st and 3rd holes were
actually used.
If you look closely, you can see that the plastic covering the center
hole has not been punctured. The reason for this is that this battery
was either used in a carbon hearing aid that had a carbon amplifier, or
a carbon hearing aid that only used two pronged plugs.
Carbon
amplifiers only had 2-pronged plugs. Plain carbon hearing aids (without
amplifiers) sometimes had 3-pronged plugs. The 3-pronged plug normally plugged
into the amplifier, and the 2-pronged amplifier plugged into the
battery.
However, you could use the plain carbon hearing aid without the
amplifier. In this case, and if the hearing aid had 3-prongs, you plugged the 3-pronged plug directly into
the battery—hence you needed a center (dummy) hole in the battery, even
though only the 1st and 3rd holes were actually used. |
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