How does the telly work?

Answer 1

There used to be a version that used rotating disks, but the normal kind used for broadcast TV in the UK, USA, etc. used a CRT.

To make the picture, an electron gun scans across the inside of an evacuated tube with

a phosphor on the inside. When the electrons hit the phosphor it glows white. To make the spot brighter, the electron current is increased. The brightness signal is encoded with

sync pulses (which control the scanning of the beam) and modulated onto a radio wave for transmission.

Originally, a similar vacuum tube technology (vidicon tube) was used for the camera. A lens

focuses a picture onto a photo-sensitive material, and an electron beam scans across it.

Where the photons of light displace electrons from the material, there is an increased current

which is amplified and used to generate the radio signal.

The sound is modulated onto a separate subcarrier and transmitted along with the picture.

Answer 2

it work when you just had to press buttons on the telly back in the daysnow it worked when you just have to use remote controls