posted by [identity profile] garnet-rattler.livejournal.com at 02:03am on 2005-03-07
The photoflash batteries are made with relatively large plate area and less plate thickness, so they can maintain a low impedance (and therefore source a large initial- and peak current for a fairly short time) even after repeated flash cycles compared to standard batteries. The tradeoff is a Much shorter life and a tendency to fade more rapidly at high(er) temperatures. This is very similar to the tradeoffs between vehicle starter batteries and marine deep-discharge batteries.

Compared to the ~state-of-the-art in 1957, modern alkalines should handily run that flash. If they turn out to die ~young, you Can still get photoflash batteries at better camera stores last I checked (~2001?).

Note that capacitors come in ~regular and photoflash varieties as well and for the same reasons. If you're building something that needs a fast, high current pulse, the photoflash caps (or 'laser discharge' caps as the larger and higher-rated units are often labelled) are well worth the premium. Regular capacitors can Easily be driven so hard by flash type circuits that they explode. Having build a few things of that sort, I have seen it happen ... ;-S Switching power supplies also require such low-ESR* capacitors and one of their major failure modes is the caps exploding in a series of high-voltage arcs.

* ESR => Effective Series Resistance or Equivalent Series Resistance depending on the source you look at.
 
posted by [identity profile] dglenn.livejournal.com at 08:47pm on 2005-03-07
Wow, didn't know photoflash batteries were still around -- useful information.

But first, to remember on which machine (and in which browser) I bookmarked the site where I can still buy flashbulbs...
 
posted by [identity profile] madbodger.livejournal.com at 11:09pm on 2005-03-07
The photoflash capacitors he's referring to are for xenon strobes. For dumping pulses
into flashbulbs, any old capacitor should do fine. Note that you should probably have
a snubber network of some sort, more to protect the camera contacts than the capacitor.

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