What is CRT

CRT is short for Cathode Ray Tube. It is true that the technology is out-of-date now. But its principle is quite simple and you may want to make one after you finishing  reading the blog.

CRT. The profile map of CRT. (http://newspaper.li/static/bff350d2a6c72f78100e026098b7e2ad.gif)
Why CRT can display figures?
The high speed electron hit the screen phosphor material to make the lighting.

How to make high speed electron?
Electron guns can produce the electrons.

How we control the figures on the screen?
We take advantage that electron deflect in the magnetic field. If you know how the signal is coded, you can decoding the signal into the magnitude of the magnetic field.