This alarm with sensors in series and parallel was found in the 1995 Encyclopedia of Electronic Circuits. The number of sensors can be changed at will.
We found this circuit in a 1986 documentation. It is based on TTL integrated circuits that can be...
This circuit was obtained from a 1968 Philips publication. The transistors are of the time. Dual...
This project, found in a 1981 documentation, consists of an interesting adaptation of the test...