My car suddenly developed multiple problems overnight. The battery wouldnt charge, the power steering didnt work and the AC compressor wasnt operating. At the garage, it was found a rodent had chewed up a couple of wires, and a belt. I had had a similar thing happen to my earlier car as well, and the car's electrical system was never the same again, after the 'repairs'. Therefore, this is one thing that I'm morbidly scared of.

So, I plan to build an ultrasonic repellent, and would like some insight towards the design. The unit would be mounted under the hood, and would blast out a burst of ultrasonic sound every few minutes;

Now for my queries; Is there a specific frequency that is most effective? Would it be smarter to use a few different frequencies, at random? Would the standard ultrasonic transducers (as used in distance measurements) be able to handle anything other (lower) than the specified frequency, usually 40 KHz? And what is a good, yet safe amplitude for the sound burst signal going to the transducer?

Lastly, does it make sense at all? Or is there a better solution?

Regards,

Anand