This simple continuity tester consists of an oscillator found in the 1983 Electronics Experimenter Special projects magazine. The circuit is powered by a single battery.
The gain of the operational amplifier shown in the figure depends on the feedback resistor,...
This circuit is from a 1970 publication. The time constant is given by 1.3R x C where R is the...
This commercial medium and short-wave radio was manufactured in Japan in the 60s. The circuit has...