Hospital bed and optical telegraph: what they have in common

1. Step 1. Hospital bed — has part — Lead screw. Adjustment by a screw.
2. Step 2. Lead screw — is part of — 3D printer. The axes are moved by screws.
3. Step 3. 3D printer — has part — Servomotor. Stepper motors.
4. Step 4. Servomotor — uses — Electromagnetism. A servo is an electric motor with feedback.
5. Step 5. Electromagnetism — is used in — Electrical telegraph. A telegraph receiver is an electromagnet that attracts an armature.
6. Step 6. Electrical telegraph — evolved from — Optical telegraph. The electrical telegraph replaced semaphore lines.

Open Evothings