This circuit was found in the February 1981 issue of Radio Electronics magazine. The circuit uses an active component of the time and is suitable for audio signals.
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...