Civilization manualBook 1: From Bare Hands to Steam and Electricity765 entries · 23 phases · 100 years
The Island
Phase 21 — Microphone, speaker, magnetic tape and the telephone exchange  /  About year 66
21.17

Photo-electric cell

light falling on a coated plate lets a current flow: a machine can see

MakingYear 66Stands on 276 earlier

AWhat it needs

Needs 276 other products in all, 2 of them directly.

View

Open a box to see what it needs. A dashed box is a product already drawn in full: click it to jump there. In the org chart, drag to move around.