4.6 Unleashing the Dog

Consider where the PIR should be mounted. Placing it behind a glass windowpane to track outdoor movement will not work since the detector cannot analyze infrared signatures. Ideally, the PIR should be placed in the unobstructed line of sight of the area being monitored. If it’s just outside your front door, thread wiring from the PIR mounted above the door to the Arduino/wave shield mounted in an enclosure inside the house.

Play with the playback audio level. The small speaker that accompanies Adafruit’s music and sound add-on pack may be adequate for testing, but it’s hardly loud enough to get the attention of anyone in the next room (let alone someone who is outdoors). Use the wave shield’s headphone jack and connect it to a powered speaker, such as a boom box or home stereo. Set the volume loud enough to get a visitor’s attention.

Attach one end of the wooden rod to the servo wheel using wire, twist ties, or rubber bands. Cover the other end of the rod with cloth, a cotton ball, or a rubber cap to protect the surface that the rod’s tip will be bumping against. You can further embellish the wire frame with a plastic dog snout from a costume store. Get creative! Just be sure not to attach something so heavy that the servo cannot generate enough torque to adequately move the attached wire.

Place the servo assembly next to a window curtain, preferably near the entryway. When the PIR is triggered and the barking audio is played back, the faux appendage will nudge the curtain and give the illusion of a dog’s nose moving behind the curtain. From the visitor’s point of view, it will look like an agitated animal is just behind the door, waiting to pounce. It will take some tweaking to get right, but once your setup is properly configured, the motion-detected playback events should look and sound very convincing!