Step 57: Handle/Electronics: Overview.
The firmware we installed earlier allows the cameras to be triggered electronically using their USB connectors. To get them to fire at the same time, you need to provide a less-than 5V pulse to them.
The two purposes of this handle system are to
A.) provide the 5V pulse to the cameras and to
B.) make the book scanner simple to use.
I have now constructed three different trigger buttons/handles for the book scanner. All three have their strengths and weaknesses. The third solution is definitely the most flexible and the least work. I'd like to show you how to make that one in detail and show the other two largely to show you what *not* to do.
Cheap LED flashlight, the kind that uses 3AAA batteries.
3 NiMH rechargeable AAA batteries.
Some kind of insulated, two conductor wire; mine came from a discarded cell phone charger. (Better if it's a coil cord.)
A momentary switch. The best kind are the "Reset" switches from old computers, though almost any will do.
A loooong 1/4 20 bolt or threaded rod (or whatever thread you like).
A wingnut, threaded to match the bolt.
A couple nuts, threaded to match the bolt.
A hunk of plastic or wood about 2" long and 1" thick.
Some washers that will fit inside the flashlight body (about 3/4").
Misc junk; industrial hot glue gun.