This rig will take a photo anytime it senses motion or heat changes
This project uses a heat sensing motion detector to trigger the shutter release button on a hacked digital camera so that high resolution images can be captured anytime a person or animal crosses in front of the motion sensing zone. By hacking into an old motion activated floodlight, the cost is kept to a minimal and based on a pre-existing system that is known to work well. This project converts the motion sensor for DC battery operation, allowing it to become portable and safe from high voltages.
This project also makes use of a circuit from a previous project called "Camera Trigger Hack", which is a pair of relays and drivers fed into the shutter release switch on a digital camera in order to mimic the original functionality of the switch. You could probably feed the output from this circuit directly into the camera shutter switch, but to be safe, the relay adds a level of isolation from the camera circuit board. Some cameras also have an external remote control jack. This could also be used.
Figure 1 - Any common outdoor motion sensor light can be used for this project
Motion sensing lights like the one shown in Figure 1 use a special heat sensor to detect movement of warm bodied creatures. This sensor detects the body heat of the subject as it passes across a pair of small sensing elements inside the heat sensor. This heat sensor is also known as a PIR (Passive InfraRed) sensor and is the magic behind every one of those inexpensive outdoor security lights as well as most indoor motion sensing units. Because these devices are mass manufactured, they are easy to find as surplus or even new for very low cost. Many security lights are tossed out when the plastic degrades or when the relay that controls the AC lights fail, so you can probably salvage the needed parts even from one that is deemed to be non functional.