We found this circuit in an American 1980s documentation. The circuit uses a piezoelectric transducer unusual in our day. The transistor is general purpose type.
We found this circuit in a 1965 Electronic Design. Transistors are still common but admit...
This circuit is from the time when cars used contact breakers. This 80's version measures the dwell...
This circuit was found in an 80s Hands On Electronics. It senses the water level in a reservoir by...