This unijunction programmable transistor circuit was found in the December 1968 issue of Radio Electronics magazine. The circuit is a half-wave control for incandescent lamps only.
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....