Interfacing a RadioShack CMOS Camera's Motion Sensor

I recently wanted to set my Axis 240 to take snapshots when motion was detected outside. The 240 has an input connector that you can use to trigger a snapshot that is uploaded to an ftp server (my Magnia SG20). To do this I needed an outdoor motion sensor as well as an outdoor camera. RadioShack fit the bill with a combination unitCatalog #: 49-2516 that works reasonably well and is very inexpensive. Image quality is not the best, but what do you expect for a $80.00 CMOS camera?

I found that by default the camera's motion sensor is NOT AVAILABLE to the user. You need to purchase a separate controller box.

This would be a simple solution, but at $80.00 it costs as much as the camera itself. The idea here is to keep the cost as low as possible.

Instead I hacked the camera's interface cable. This gave me access to the motion sensor signal. The signal is TTL logic HIGH when there is no motion and LOW when motion is detected. A simple circuit - two transistors, two resistors, a diode, and a relay - gives a dry contact output on the camera interface. I put it in a small project box, you can even skip cutting open the camera's cable by purchasing a PS/2 mouse extension cord and cutting into it instead. (the camera uses a PS/2 style connector at the interface end)

PS/2 style 6 pin connector. Ground is shell.Pins 1 and 5 are PROBABLY speaker.imageTransistors are standard NPN type switching transistors.Relay is PC Mount DPDT 12vdc 50ma coil.Diode is just a check diode. A 1N414 works nicely.I use the second set of contacts to light an LED to indicate activity.You can power the circuit right from the 12vdc running to the camera.I highly recommend you buy a PS/2 extension cord and cut it in the middle,instead of cutting into camera cord(s).