Battery–capacitor flash

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.

Advantages

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

• Photoflash battery

References

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