This circuit uses a resonant reed relay to recognize the frequency of an input signal. Adaptations can be made to obtain functioning as a shield. The circuit is from 1965 documentation.
This small signal injector generator was found in the February 1971 issue of Radio Electronics magazine....
This amplifier, found in a 1981 publication, provides 15 W lHF power with a supply voltage of 14.4...
This simple passage alarm is powered by the power grid using an LDR as a sensor. The circuit is...