This different circuit was patented and described in the Radio Electronics magazine of March 1958. In that section it used to present different configurations that received patents.
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...