This circuit for very low frequencies was found in an American documentation from the 90's. Transistors are for general use and the frequency depends on C1 and C2.
This circuit was found in the April 1971 Radio Electronics magazine. It uses common transistors and can...
This voice scrambler and descrambler circuit was found in a Radio Electronics from July 1963....
Using a 4017 as a base, this circuit from a 1990s Popular Electronics generates low-frequency...