Suggested by Maxim in documentation from the 90s, this circuit has its response curve given next to the diagram as well as the formulas for the component calculations.
We found this sensitive moisture detector in an old documentation. The circuit uses a common JFET,...
This stethoscope or hearing aid amplifier has excellent gain. It was found in Popular Electronics from...
This transistorized circuit appeared in a Radio Electronics magazine in March 1958. The frequency range...