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

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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)

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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):