This very detailed Dimmer was found in an English documentation from the 90's. The SCR could be a modern equivalent like the TIC106. The circuit is only suitable for incandescent lamps.
This alarm with sensors in series and parallel was found in the 1995 Encyclopedia of Electronic...
This integrated amplifier was used in televisions from the 70s, with good sensitivity...
This source, found in a publication from the 1980s, uses an integrated circuit that is uncommon today....