This alarm circuit with NC sensors in series was taken from an article in Radio Electronics magazine from May 1971. The SCR can be any of the 106 series.
This switching power supply was found in an Electronic Design from the 90s. The components are...
This burglar alarm is highly efficient, depending of course on the care with which it is...
This circuit is from a 1969 Electronics World. The transistors may be modern general-purpose...