Found in a 1968 Electronics World, this circuit uses components from the era. In this circuit, a small incandescent lamp is activated when it gets dark.
This circuit is from American documentation from the 1980s. The transistors are general purpose...
This circuit was found in a Popular Electronics of the 1990s. The sensor is a rotating mechanical...
The purpose of this circuit is to sense the water level in the windshield wiper reservoir. The circuit...