This circuit was taken from an old American documentation. It can be built with modern op amps. The power supply does not have to be symmetrical.
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...