Found in Popular Electronics from the 1980s, this circuit uses two operational amplifiers from that time. The circuit has frequency and symmetry adjustment.
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...