Battery–capacitor flash

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Polaroid BC flash model 281

A battery–capacitor flash (BC flash) is a flash photography system used with flashbulbs. Instead of relying directly on the current pulse ability of a battery to directly fire a flashbulb, a battery is used to charge a capacitor that is then discharged through the flashbulb. BC flash units use 5.6V, 15V, or 22½V batteries.


The advantage is that even with an aging battery, the flashbulb still gets a high current pulse and thus reliably fires, although the recycle time between flashes increases as the battery ages.

See also[edit]


  • Electronics for Photographers, by Marshall Lincoln, Copyright 1966 by Chilton Books, pp 43–54.
  • Capacitors & Batteries, Boston University Physics Department