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.
This voltage calibrator circuit using a zener diode was found in Radio Electronics magazine from...
The relay of this circuit closes when the position set in P2 is reached by the sensor...
The purpose of this circuit, which we find in an old American documentation, is to allow the...