Wave theory and programmable logic controller: what they have in common

1. Step 1. Wave theory — uses — Sound wave. Sound is a wave.
2. Step 2. Sound wave — is used in — Phonograph. It records sound vibrations as a groove.
3. Step 3. Phonograph — was inspired by — Electrical telegraph. Edison came to the phonograph while working on recording telegraph and telephone signals.
4. Step 4. Electrical telegraph — has part — Relay. Relays boosted the signal on long lines.
5. Step 5. Relay — evolved into — Programmable logic controller. It replaced relay cabinets.

Open Evothings