There is a schematic and a parts list in the PDF a person could use if they wanted to build from scratch, I was not suggesting buying the kit. At 150 micro-amps at idle, this is a fairly efficient design, and their stuff works well. I have used several "camera controllers" that have this as their basic circuit, although some changes have been made to it.
This is only part of what is usually needed for a camera controller. The Picaxe would be used for timing. Some cameras (but very few) can be used as an "always on" meaning the camera is not turned on and off with each detection. These cameras will go into a sleep state after a while, but can be quickly waken to get the picture., After an extended time, 3~4 hours on some, the camera turns off, where the power will have to be cycled to get it working again. In cases like this a "refresh" is given to the camera by pressing the half press (focus button) to keep it from turning off. The refresh time for an Olympus 370 and 380 would be 2.5 minutes if you want the camera to stay awake. This will consume 2500ma NIMH batteries in about 10 days, but a picture can be taken by the camera in less than one second. With a refresh every 2.5 hours, the camera does go to sleep, but can be awaken to get a picture within about three seconds or less...depending on how long it has been since the last refresh. This will extend the battery life to about two to two and a half weeks on the 370 and 380.
Most cameras will be used as an "on-off" Meaning the camera turns on, takes the picture and stores it, then turns off again to save batteries. The Picaxe would be in charge of the proper timings for power button press to turn it on...some need a longer press than others, as well as longer times to hold it to turn it off again. Then different cameras need different wait times before they can shutter a picture. Some will be ready within a second, and some will need several...up to 10 in some cases. Usually the flash cap drains off on these cameras, so a periodic "refresh" is used on these too, to keep the flash ready to fire.