Why capacitors are used in flash cameras

In place of the photoflash capacitor, use a smaller, high quality capacitor, reducing errors associated with the non-ideal photoflash capacitor. Using an adjustable load, the output voltage can be set anywhere between ground and the maximum output voltage. Figure 5 shows the efficiency for the circuit in Figure 1, which was measured using this method. This method also provides a good means to compare various charging circuits since it removes the variability of the photoflash capacitor from the measurement.

The total efficiency of the circuit, charging an ideal capacitor, would be the time average of the given efficiency curve, over time as V OUT changes. Linear Technology Corporation has worked with several transformer manufacturers including TDK, Pulse and Sumida to provide transformer designs optimized for the LT that are suitable for most applications.

Please consult with the transformer manufacturer for detailed information. If you wish to design your own transformer, the LT data sheet contains a section on relevant issues. Here, multiple LT circuits can be used in parallel. The upper most circuit in the figure is the master charger.

It operates as if it were the only charger in the circuit. The charging time for a given capacitor is inversely proportional to the number of chargers used. Three chargers in parallel takes a third of the charging time as a single charger applied to the same photoflash capacitor. Figure 6. This professional grade charger uses multiple circuits in parallel to quickly charge large photoflash capacitors.

The LT can be easily interfaced to a microcontroller. By utilizing these pins, the LT can be selectively disabled and enabled at any time. The microcontroller can have full control of the LT This might be necessary during a sensitive operation in a digital camera. With many types of modern batteries, the maximum allowable current that can be drawn from the battery is limited. This is generally accomplished by active circuitry or a polyfuse.

By blocking the DC and yet permitting the passage of AC, the device can be used in parallel with another circuit element to allow AC to bypass the element without passing the DC portion of the signal. Capacitors are regularly used this way in television, radio, and audio amplifiers.

Because of its capacitance value, a capacitor is nonresponsive to low frequency signals, making it useful for segregating an input signal with mixed frequencies. For capacitors in an AC circuit, the current flow increases with frequency, whereas the capacitance reactance or the resistance to flow of AC is inversely proportional to the capacitance value. Therefore, a capacitor can be designed to have minor opposition to current flow for the high frequency portion of the signal while offering greater opposition to the lower frequency current, thus making it useful for filtering out a desired frequency range.

Such capacitors are commonly used to detect radio frequency as part of the tuning circuit for television and radio devices. Capacitors are often used to stabilize the voltage to sensitive devices by absorbing excess energy generated from undesired transient voltage surges and eliminating arcing of contact points. This particular application accounts for a large portion of all multilayer ceramic capacitors MLCCs used.

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 current pulses without excessive internal heating. Tough caps! Add a comment. Active Oldest Votes. Dave Tweed Dave Tweed k 16 16 gold badges silver badges bronze badges. Is it correct to assume that this shape is not only due to the form factor required but also helps reducing the ESL?

I saw a v spike across that 0. It eventually blew the coating right off the resistors. Sign up or log in Sign up using Google. Sign up using Facebook.