This sensitive motion sensor with inductive sensor was found in a 90s Elektor. The circuit uses only transistors to activate a buzzer.
This circuit was found in old documentation, appearing in several ways in this section. PUTs are...
This version of mixed is one of the many that appears on the website using the 741. The circuit was...
Found in General Electric's 1966 documentation, this circuit uses company reference diodes, which are...