We found this circuit in a Popular Electronics from the 90s. Transistors can be modern equivalents. Observe the high supply voltage.
In a voltage follower, the voltage gain is unitary, the input impedance is very high, and the...
This circuit has the coil tuned input according to the operating frequency range. The indicator can...
This circuit was originally designed for the practice of Morse code, something common in 1966, the year...