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 small telephone transmitter uses a telephone capsule as a microphone. The L1 coil has 4 to 5...
This circuit was found in an American documentation from the 1980s. The sensitivity ranges from...
This circuit produces a sinusoidal signal whose frequency can be calculated using the formula next...