This circuit was found in an American 1980s documentation. The transistorized step is the receiver's last IF and the diode is the receiver's existing detector.
This circuit converts pulse frequency to current, which is indicated on an analog instrument. The...
This relay circuit with a dual channel MOSFET (not very common today) was found in an old American...
In the figure we have a simple signal tracer circuit to be coupled to the volume control of an AM...