We found this circuit in a 1968 General Electric publication. The circuit uses an SCR of the time, but any modern equivalent can be used. The relay must have contacts that support the horn current.
This alarm, found in a 2002 documentation, uses several sensors and has a 12 V supply, not...
This circuit uses a special 1950's RCA strobe tube. It can be built with equivalent components for the rest...
This circuit, which can act as a shield, was found in a 1970s American documentation. The...