This circuit for very long-time intervals was found in the March 1993 Radio Electronics magazine. Times of several days or even weeks can be achieved depending on the value of C1.
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...