This sensitive circuit was found in the August 1971 issue of Radio Electronics magazine. The SCR is equivalent, and the transistor may be a BC548. The load may be a relay.
Found in the July 1968 Supertena Bulletin of a Popular Electronics, this receiver makes use of the...
This switching source was obtained in a 1976 National Semiconductor manual. For the indicated...
This configuration appears several times on this site. The circuit can generate a 100 kHz or other...