We found this circuit in a technical documentation for the National Semiconductor LM3909. The circuit consists of a low consumption continuity tester powered by a single battery.
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...