Signedplate on front: GENERAL (GE logo) ELECTRIC / Tungar / REG. U.S. PAT. OFF. / BATTERY CHARGER / CAT. 277153 60 CYCLES 115 VOLTS A.C. 3 CELLS 2 AMP. / 48 CELLS .25 AMP. USE BULB CAT. 277465 / GENERAL ELECTRIC CO. / N.P. 29843
plate on side: HARVARD UNIVERSITY / GOVERNMENT PROPERTY / 00076 D00285
Inscribedin black on side: K B / LYMAN 130
FunctionTungar Power Supplies and Chargers use an very interesting vacuum tube called the Tungar Bulb or Tungar Rectifier. Invented in 1914 by General Electric by G. S. Meikle. In some respects it looks like a light bulb with a plate over the filament. When you turn on a Tungar Charger, the bulb does light up like a bulb. Tungar is an acronym for Tungsten Argon (Tungsten filament filled with Argon gas). The Tungar Bulb has the ability to handle large amount of current and was relatively immune to shorted battery cells which makes it the ideal battery charger. Tungar chargers were used to charge radio storage A batteries and car batteries. The Tungar Bulbs were used in many high current applications until the late 1940's, when selenium rectifiers became practical.
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Related Workshttps://www.radiomuseum.org/r/general_el_tungar_battery_charger_for_a_and_b_batteries.html