Camera Trap

Camera Trap Design

Version 1

The brains of the trap is an Arduino micro controller board. This has an ATMega controller and support circuitry and is easy to connect to a solderless breadboard. The camera shutter is controlled via a remote cable made from a CD motherboard cable. The cable has three wires. Shorting two together causes the camera to auto-focus and shorting the third causes the shutter to fire. This was accomplished with two 5V relays. Since the Arduino can not source enough current to trip the relays, two MOS FET transistors were used to trip the relays.

The first version of the camera trap used an IR LED and photo transistor as the trigger. The IR LED was positioned such that the IR light from the LED hit the photo transistor. The transistor was connected between a 1K Ohm and 10K Ohm resistor divider. This was fed into an analog input of the micro controller.

All the custom logic was built on a solderless breadboard which the Arduino board just plugs in to. Everything was held in place using hot glue. It was remarkably robust.

The main problem with the version 1 design was the LED emitter could get knocked out of alignment with the receiver. This would cause the trap to continually trigger the camera. We attempted to remedy this by fixing the emitter and receiver to a board. While this solved the alignment issue, the only wild animals that would go near it were raccoons, and only if it was baited.

Version 2

For version 2 we used a Parallax PIR motion sensor. This sensor, adjusts to the background IR, and then when that changes raises an output. This is connected to an Arduino digital input. Firing the camera was as before, although we changed to a soldered breadboard to reduce size so the assembly could be fit in a housing.

The problem with the PIR sensor was that at night it would adjust to the background IR and then if vegetation moved due to wind it would fire. It did not have this problem during the day because the background IR was much higher.

Version 3

For version 3 we switched to a Parallax PING))) ultrasonic sensor. This sensor sends out an ultrasonic sound pulse and then times the echo return. The shorter the return, the closer an object. This is very difficult to fool because it really needs an object to trigger it. Unfortunately, the software required to use the sensor is more complex.

This version worked well with bait as well as without bait on a path frequented by wildlife.

Photos

The photos below were captured using our camera trap.

Comments

Cute kitty whose cat is she?

Nice work Ian. I especially liked all the cool cats parading through on poker night!

-- MattNathanson^? - 26 May 2008