Suggested by General Electric in a 1965 document, this circuit can accept a greater number of sensors. When anyone opens the SCR it fires powering the load.
This circuit uses a Hall device from that time as a sensor. The circuit is from an English...
Found in Radio Electronics from the 90s, this siren finds many variations on this site. The...
This audio generator that produces both rectangular and sinusoidal signals was found in a...