This circuit was found in a Popular Electronics from the 90s. The circuit uses a general purpose JFET. The coils depend on the signal range that must be amplified.
With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of...
This circuit was found in an American 1980s documentation. It analyzes the exhaust gas of a...
This Colpitts crystal oscillator was found in an American publication for amateurs in the 1980s....