My Pecute Ultrasonic Dog Repeller mysteriously vanished while I waited for larger piezo electric tweeter to come. My brother, where I first seen the Dog Repeller still had his. Surprisingly, the small speaker in his repeller worked. Since dogs to not react at distance I expected, I assumed no sound condition.
Left circuit is repeller sending signal out. Right is piezo tweeter( 20 K ohm resistor) hooked to probes into an oscilloscope. Observe positive and negative terminals on piezo tweeter.
I found to increase loudness greatly I had to bring dog repeller very close to piezo tweeter. Much closer than I would wish a dog I wanted repelled to be. Basicly, putting the repeller in dog's ear to get the loud signal strength. Distance at high frequencies only rises sharply very close output speaker.
