One question a little ot: The switch, what would you recommend for positioning it? Should it be near the camera or doesn't it matter?
It's highly unlikely that any significant amount of noise will be picked up by the cables, so it probably doesn't really matter.
And furthermore: I'd like to keep the possibility to trigger the cams with slight delays, so I'll use a 54-channel Arduino.
Are you still planning to use individual supplys for the cameras? I presume if so, you will (or already have) connected the Grounds together?
Keep in mind that the ADC input has a 20Kohm(?) pull-up resistor that pulls it up to just over 3 volts. I'm not entirely sure what would happen if the input went up to 5 volts from the arduino, you might have to either make sure the arduino never pulled the output high (instead of setting a pin high, use
pinMode() to set it to an input so it will be floating ie. effectively disconnected) or, safer, use a simple resistor voltage divider to reduce the voltage. You probably want to keep it below 2 volts if the camera is to think the battery is in the normal operating temperature (not that they really shut down or anything anyway)
I'd also imagine this could be done in code on the cameras, but probably take more work than just using an arduino.
Should I have a look at a good shielding or would you say the kind of signal is stable enough?
Also unlikely to be a problem, whatever's easiest/cheapest should suffice. However to be 100% certain you may want to test how well it works with one camera before buying several hundred meters of wire.
I haven't really been keeping up with this thread that much, how did you go about with modifying all 50 dummy batteries? Or are you going to make your own?
