This circuit was obtained from an 80s factory manual. The integrated circuits used are uncommon today, but the diagram is for reference only.
This circuit was found in a 1977 publication, but it can be easily assembled, although unijunction...
This alarm circuit was found in a 1982 publication. It uses components that can still be found...
Found in 90s 303 Circuits, this circuit is intended for interfacing analog black / white computer...