This circuit is from a Radio Electronics from October 1970. The circuit uses transistors from that era and has a low impedance output. The resistance R1 depends on the impedance of the input signal.
This oscillator was found in the November 1986 issue of Radio Electronics magazine. The frequency...
This sophisticated circuit with a low, medium, and high treble filter is from 1990 documentation. The...
This circuit was obtained from a 1998s Popular Electronics. The magazine no longer exists, but the...