This simple audio signal tracer or follower can be made with a BC548 instead of the original transistor. The output is made in a small crystal phone. The power can be from 5 to 9V.
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...