This simple logic level tester was found in Radio Electronics from the 90s. The inverters are of the 4009 type and the power comes from the circuit being analyzed.
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...