This circuit is intended to recover a very weak signal at a receiver, for example, a CW signal or a tone signal. The circuit is from a Popular Electronics from the 90s.
To use the instrument for AC measurement, the tips are A and B. For CC use tips A or B for...
The interesting circuit shown in the figure, can have its gain digitally controlled and present two...
This simple MW radio was found in a 1975 publication, but it can be mounted with BC548...