This signal injector and tracer (follower) was found in an old American documentation. The transistors can be general use and power is made with one or two common cells.
The circuit presented is from an old magazine having been translated and published in a national...
With this name, we found this electronic stethoscope with a coal microphone in a 1957 Raytheon...
This circuit should be placed between a turntable and recorder or playback media from the input to...