A photoflash capacitor is a low capacitance, high voltage capacitor used in flash cameras, professional flashes, and solid-state laser power supplies. Their typical purpose is to power a high voltage flash tube, which then illuminates a photographic target or optically pumps a laser rod. As flash tubes require very high current to operate, photoflash capacitors are designed to safely supply high discharge currents without excessive internal heating.
Nominal voltage for a small camera's photoflash capacitor ranges from 300-330 volts. The nominal capacitance is around 80-160 µF (microfarads) in most disposable cameras. Their temperature ratings are often mediocre in comparison to other capacitors, typically 55°C (compared to 85°C or greater for regular capacitors). Professional photoflashes may have larger flash tubes, and contain larger capacitors to supply the appropriate power.
Due to their ability to deliver a pulse of high current, photoflash capacitors are sometimes used in railgun and coilgun designs.
The disadvantage of electrolytic capacitors is the non-ideal, lossy characteristics which arise from the semiconductive oxide properties, double-layer effects from the electrolyte-oxide charge-space region, resistive losses from the high electrolyte resistivity, frequency response rolloff due to the roughness of the surface oxide, and finite capacitor life due to breakdown and degradation of the electrolyte.
The tab paths are generally run from the capacitor section to the terminals in a fashion which keeps the inductance low and prevents tabs of the opposite polarity from coming in contact with one another or the case during movement and vibration of the capacitor unit.
Photoflashcapacitors used in built-in consumer camera applications are generally in the range of 100 µF 360 V, and may approach several hundreds of microfarads in the separate camera-top units.
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