This repellent operates with frequencies from 30 to 45 kHz, serving for insects and rodents. The circuit is from 80s documentation. The transducer is a piezoelectric type.
We found this amplifier for automotive use in the Philips integrated circuit manual from 1990. The...
This interesting circuit records a few seconds of audio signals, reproducing them in a small...
Settings like this can be found at various points on this site. The trigger door can be a 4093...