This circuit was found in a Popular Electronics from the 90's. The output signal can be applied to a headphone or speaker. The microphone can be a piezoelectric tweeter capsule or other type.
Found in a 90s Popular Electronics, this circuit is intended for amplifying analog video signals....
This antenna amplifier or booster for receivers from 100 kHz to 30 MHz was published in a...
This somewhat complex circuit was found in the May 1984 issue of Radio Electronics magazine. The...