This filter, which rejects frequencies around 1 kHz, was found in the August 1993 Electronics Now magazine. The fine tuning is done at R3, and the source must be symmetrical.
This 1992 circuit operates in the range of cordless phones used at the time. The circuit is based...
This different circuit uses a relay as an oscillator, whose frequency is determined by C1, and to...
This antenna or booster amplifier operates with signals from the midband (MW) range up to the VHF...