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.
Found in the 1976 Siemens transistors manual, this circuit works with AM or FM IF signals. In the...
Three 4011 NAND gates and two more components - a resistor and a capacitor make this oscillator very...
This photoelectric circuit was found in a 70’s Ferranti's documentation. The circuit uses an...