Picture of Invisible Signally Beacon (Infrared LED Throwie)

Spies need ways to secretly communicate with their partners. This can be a simple signal like a chalk mark on a wall or a newspaper left on a park bench. But the best kind of signal is completely invisible. In this project, I am going to show you how to make a simple invisible beacon that you can use to signal your friends and accomplices.

Step 1: How the Invisible Beacon Works

Picture of How the Invisible Beacon Works
This design uses an infrared LED as the signally device. Infrared  light is invisible to the human eye. However, digital cameras are able to detect these wavelengths. You can observe this by pointing your TV remote at a digital camera and pressing a button. To the camera, the infrared LED will appear to light up bright purple.

By using an infrared LED and a digital camera, you can send and detect signals that will be invisible to everyone else.
kevsaul1 year ago
The camera trick does not work on my iPhone 5s but does work on iPad 2
Tanmayg kevsaul4 months ago
It doesn't work with my iPod too. I don't know why.
DIY Hacks and How Tos (author)  kevsaul1 year ago
There are a few cameras that have an infrared filter to try to block more of the near infrared spectrum.

You I-Phone has an Infrared block filter, which blocks infrared Light! Most DSLR´S have them :)

Throw that in a battlefield and watch the laser guided missile hit it.lol

Gula1 year ago
Look at is with the camera on the screen side, it does not have a ir filter.
Ploopy1 year ago