Over the past year or so, a friend and I have been mulling over a device that can be used in a variety of ways to deter animals from entering certain perimeter areas – such as keeping a dog from doing his business at the front gate of your house. There are other applications as I have learned that apply to keeping wolves off of ranches, or keeping coyotes away from designated areas.

The high level design involves a circuit that produces an ultrasound output at about 20 KHz combined with a circuit that detects motion and size. The motion detection and sizing will come in the next phase of design, since there are a lot of infrared and ultrasound solutions to work with. No matter where I looked in Akihabara or elsewhere for a 20 ~ 24 KHz ultrasound solution, it seemed that none was available, so I turned to Google. This link presents a rather militant solution that will probably make the creator and tester of the circuit deaf by the time the design is complete. Through the Google journey, I also came along this link, which is a forum dialogue that shows how deviant some of these electronics geeks can really get… looks like a neighbor or two have unknowingly lost their hearing as a result of electronics experiments. Then to get into the science, this link helps but don’t read it right before going to bed. Finally, I decided it was time to create a simplified circuit as that displayed in the first link above. That schematic proposes two NE555 timers – one to generate the frequency and one to pulse as the dog barks, which is probably most effective. In other words, if one half second after a dog barked, if a pulse of irritating noise is heard, the dog will stop barking.

This design and approach slightly differs from the WanAway objective, which is to deter such animals as they approach a certain point. Therefore, our objective is to increase power as the dog approaches, so the dog does not react to a counter-action, but reacts to an irritating noise that it hears when approaching that gets more irritating the closer it gets. So I adopted the design above and removed the first NE555 timer. The result works quite well on the neighbors poodles, our Jack Russell Terrier, the black lab down the street, and on our black cat Gizmo.

After making the first prototype created above, I wondered why it would only work when I first turned it on, then the dog would go on barking – the answer, as described above, is that the dogs barking is a reaction to the pulse. However, when you hold this device in your hand or place it strategically in the front garden in an area where you do not want the dog to go, it is quite effective too. Yesterday, I hooked this up to the oscilloscope to get 24 KHz coming out of the device, and this seemed to be very effective – you could see Keith’s (our Jack Russell) ears peel to the back of his head immediately. Poor guy….. heh.

Okay, now this is a tad bit inhumane but my intention hear here is not to be cruel to animals. This is probably the most humane way to deter barking and other animals from entering a perimeter, so please limit comments to the electronics involved or other ‘ideas’.

Finally, and not least, I feel the need to justify the Japan category on this posting. The word ‘wan wan’ in Japan is the onomatopoeia for the english word bark – i.e., basically “Rrrrrufff!”. However, Japanese use such language as part of a sentence and situational description more than we would use “Ruff” in the typical spoken English language.
Cheers!