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 appeared in the June 1990 issue of Radio Electronics magazine. Integrated circuits must...
Lockout shooting, due to the incidence of light, can be achieved with the circuit in the figure. In...
This circuit can function either as a crystal or galena receiver with a pre-amplifier using a FET...