Video explanation
A key closes a remote circuit; an electromagnet drives a recorder that marks dots and dashes on tape, followed by an exploded view.
Encoding with pulses
Dots, dashes and gaps encode letters through duration, so timing carries information rather than current magnitude alone.
Electromagnetic conversion
Current in a coil creates a field that attracts an armature, converting an electrical signal into motion.
Local circuit and recording
A relay can control a local receiving circuit, while the tape mechanism stores pulses as marks.