This circuit was found in a Popular Electronics from the 90's. Its purpose is to detect the ionization of the air. The meter can be replaced by the current scale of an ordinary multimeter.
The purpose of this game obtained in a 1998 documentation is to guess the number that the circuit...
This circuit is from the 2005 Linear Technology Application Manual. The circuit must be powered by 5...
This circuit generates excellent sinusoidal signals and has the frequency adjusted by VR1 which is...