This circuit was found in a 1965 General Electric manual. What it does is give a warning if you leave the vehicle with the headlights on or lights inside.
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...