We found this circuit in a documentation from the 70s. The circuit uses amplifiers from the time, but it can be implemented with modern equivalents.
This circuit for VCR recording heads was found in the February 1990 issue of Radio Electronics magazine....
This very simple continuity tester uses a small 1.5 V lamp (type used in flashlights). Can be...
This commercial radio with 3 earphone listening transistors was manufactured in Japan in the...