In this phase shift circuit, the transistor can be any general-purpose transistor. The circuit is from an Electronics Now issue of June 1993.
An interesting type of sensor for specific applications is the sensor formed by piezoelectric...
This circuit is from Radio Electronics from the 90s. It supplies a voltage between 800 V and 2 000...
This circuit was obtained in a 1989 publication and is quite simple to assemble, but critical in...