We found this circuit in the December 1968 issue of Radio Electronics magazine. The circuit is used with high-impedance magnetic headphones. The transistors are from that time.
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...