Need electronic dog whistle? It is widely known that dogs can hear sounds with frequencies higher than the humans cant hear. Sound frequencies higher than 20 kHz can be hardly detected by humans but animals are very sensitive to it. Basing this fact, an electronic dog whistle can be constructed and used to call dogs back from long distances.
The circuit featured here uses a piezo-ceramic element to generate the necessary high audio frequency. The oscillator generates a squrewave signal which consumes less current than a sinewave. The oscillation is produced by gates U1…U3, R1 and C1. These components work as an stable multivibrator in the circuit. Since the piezo-ceramic introduces a capacitive load into the circuit, it generates high frequency spikes during voltage level changes.
Transistors T1, T2 and T3, T4 serve as signal amplifier. Gates U4…U6 invert the signal from gates U1…U3 and create a bridge. The electronic dog whistle circuit is powered by a single 9 volt battery and generates a frequency of about 21 kHz.
This dog whistle generates an output voltage of about 15 volts p-p. It sends out a sound signal of around 101 dB! One word of caution in using the whistle. Small babies are found to be sensitive to this sound although mature people don’t hear it. So, never use the dog whistle near babies!