flashes and whining

Factual Questions
1

hello.

no, this is not a PitRant asking why i never get flashed by old pervs in the park. although now that i think about it…

as a camera’s flash charges, there’s that high-pitched whining sound. why is that?

an old physics teacher (great teacher, but a bit on the physics-teachers’-urban-legend side), when i asked, said that manufacturers put a little whining thing in there. for some consumero-psychological reason, rather unclear.

what’s the deal? capacitors don’t make noise all that often, do they?

thanks,

jb

2

The whine is caused by the oscilating action of a feedback circuit which gradually increases voltage as the capacitor is charged (which is why the whine increases in frequency.)

There’s a more detailed explanation here.