How do remotes work?

If you are lazy like me, you are going to love using the remote. They let you operate a television/ airconditioners/ music systems/ garage doors from far away without having to go close to the machine. Nicole Tesla was responsible for this invention. If you look at a remote there usually is a small LED on the front vertical face of the remote; in some others, it may be covered with a small piece of plastic. But when we press a button why do we not see any light?

Here is why-
All of us have learnt that apart from the VIBGYOR colours, there are some invisible colours in the light spectrum. There is infrared beyond the red light and ultraviolet beyond the violet colour. Remotes use ultraviolet rays. Some people think it is some kind of radio waves, but if it was actually radio waves, it would work even if we pointed the remote away from the television. The remote works only if you point it directly at the appliance or if you point it towards a reflective surface such as a mirror or glass.

Ultraviolet is invisible to the naked eye. Hence, we cannot see any light signal coming out of the LEDs. But there is a way!! Our cell phone cameras are equipped to detect UV light. Try this by putting any digital camera in front of the remote. When you press a button you can see a beam of ultraviolet light through the camera but not with your eye.

Image credits: Quora

Now when there is a flash of light, how does the television distinguish between a volume up button and a volume down or any other kinds of buttons. It uses a modified version of the binary code. The appliance sensor sees the pattern between the 'ones' and 'zeroes'. When the appliance is on from the main power switch, it starts searching for signals. These are the some of the basic codes:

• Channel Up- 001 0001
• Channel Down- 001 0001
• Power On- 001 0101
• Power Off- 010 1111
• Volume Up- 001 0010
• Volume Down- 001 0011