This circuit was found in an Electronic Engineering of the 80s. The circuit indicates when a telephone line is being used, being useful in case of extensions.
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...