##Introduction## To get the cameras to trigger simultaneously, we chose to trigger them via USB using a feature of the CHDK. Dual camera 555 trigger ##Assembling the 555 circuit## * Pretty good instructions come in the 555 timer package * Potentiometer confusion * Stripping and attaching the USB cables Dual camera 555 trigger ---- ##Connecting the batteries##
5 coin cell batteries + 1 screw fit in the holder Place them inside one by one
###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. Four should fit snugly and securely ###Attaching to the 555 timer (extra wire)### (coming soon) ---- ##Splicing USB cables##
Snip the USB cable to at least 8 inches long
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): Separate out the wires from the wrapping Snip off all but red and black; strip off their wrapping