##Introduction##
To get the cameras to trigger simultaneously, we chose to trigger them via USB using a feature of the CHDK.
##Assembling the 555 circuit##
* Pretty good instructions come in the 555 timer package
* Potentiometer confusion
* Stripping and attaching the USB cables
----
##Connecting the batteries##
###Battery selection###
* Two different batteries are needed:
* a 12 volt battery to run the timer, and
* a 5.5 volt (or more) for actually triggering the camera.
To keep things simple, and because it's hard to find an efficient, cheap and lightweight way to hold 4 cell batteries, here we show how to fit 4 coin cell batteries into an N-type battery holder, which is provided in the dual infrared kit -- using a small wood screw.
This is a bit of a "hack" but has worked very well - 4 1.5 volt batteries is ~6v and very little current is needed to actually trigger the camera.
###Attaching to the 555 timer (extra wire)###
(coming soon)
----
##Splicing USB cables##
Using a wire stripper, cut at least 8 inches of USB cable, preserving the smaller connector. Strip off the plastic wrapping to expose the smaller wires within.
Image dump (more description coming soon):
