This circuit was found in a 1970s RCA publication. Transistors support modern equivalent types. Observe the dimensions of the explorer coil.
This amplifier, found in a 1980s documentation, should be powered by a symmetrical source. Modern...
This circuit from a Popular Electronics from the 90's can generate signals from 0.03 Hz to 3 kHz...
This fiber optic receiver was obtained from a 1978 documentation. We can use any modern...