This simple tester was found in a Popular Electronics from the 90s. The circuit is powered by two 9 V batteries since it requires a symmetrical source.
Found in old documentation about neon lamps, this circuit produces very low frequency signals that...
In the figure we show how to use a small Hartley oscillator as a continuity tester. The component...
In the figure we have a interfacing circuit of TTL logic as CMOS logic using a 6N139 optical...