This CMOS integrated alarm was found in the July 1992 Radio Electronics magazine. The circuit has a small power stage and its sensitivity is adjusted at R5.
This circuit was found in 1980s American documentation. The transducer is a piezoelectric capsule and the...
This circuit from the 80s uses an integrated circuit from the time. The CI is difficult to find...
This receiver, which, depending on the coil, can receive medium or short waves, was found in a...