This voice scrambler and descrambler circuit was found in a Radio Electronics from July 1963. Transformers are common types at the time with impedances according to telephones and line.
This photoelectric circuit from a 1960 publication uses a 6.3 V electromechanical counter, common at...
We found this circuit in a magazine 73 from the 90's. It is a circuit indicated for radio-amateur...
) This circuit uses two 4046 CMOS PLLs to produce a modulated signal of good intensity. The MOSFET can...