okay, i played around a bit, managed to use a "remote switch" on both my a620 and s3is - it switches ON when it gets dark. i plan to use it in conjunction with a properly attached laser beam, so when the beam is interrupted, a shot will be taken. for highspeed photography, for example when you drop an egg, on its way down it interrups the laser beam.
i bought an extremely cheap solderless "experimenting board for kids".
however, i think i'm running 9V through my camera and i dont know why and how. attached are both the "circuit" plan from the book and the "real setup". i replaced the red diode (1.8 V) with two USB connectors, and then i found out that the whole 9V are on the contacts. so i replaced the 1K resistor with a 1M resistor: voltage drops down to around 4,5 - but that isnt enough for the cams to detect. so i replaced the 1M resistor with two 470k resistors (as in the picture), that triggers the cams but when i detect the voltage with voltmeter i still get 9V. either i'm dumb (long time ago i had physics in school about the exact same matter but i forgot...) or plain blind.
question: is it me using my voltmeter the wrong way or is there really 9V getting to my cams? what should i do to downsize that to 3V (dont wanna risk breaking something!).
the ldr is a light-dependent resistor (much light - 100 ohm, no light 1M ohm). the transistor is the "standard" transistor BC547.
maybe some of you more experienced users can shed light on this

edit: i know that the usb detection routine isnt that fast to detect a falling egg. but maybe i have to drop it from a much greater height
