This circuit was found in a Popular Electronics from the 90's. It consists of the solid-state variation of the well-known grid-dip meter. MOSFET is a component not very easy to obtain these days.
This circuit was found in an English publication from 1967. The circuit is for listening on a...
This circuit allows you to use a digital multimeter as a thermometer. The sensor is mounted in a...
This configuration, which appears in other articles on this website, was found in a European...