This circuit allows the detection of RF signals using the lowest range of direct currents of a common multimeter. Equivalent diodes such as 1N34 can be used. The circuit is assembled in a ballpoint tube.
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...