With this circuit it is possible to measure RF signals with a common multimeter. Signals up to 200 MHz can be detected. The diode supports general-purpose equivalents.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...