This circuit was found in an American 1980s documentation. It analyzes the exhaust gas of a vehicle using a special sensor. The indicator is a milliamperimeter.
This configuration can be found in other articles on this site. This was obtained in 1998...
This circuit generates both white and pink noise. The transistors can be BC548 and the power...
Found in 90s Radio Electronics, this shield can control high voltage loads in the power grid....