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.
This circuit activates a buzzer when the voltage applied to the input falls below a preset value in...
This simple window comparator based on the well-known LM339 was found in the June 1998 issue of...
This circuit, which can act as a shield, was found in a 1990 PE Hobbyst Handbook. The circuit...