Surprisingly simple code is all it takes to pass a secret code on a 7-segment LED display.

This was inspired by a conversation with someone learning about LED multiplexing and I got to wondering...what if you use the multiplexing refresh rate to your advantage?

Here's an example that my escape room friends will find really cool...

A 7-segment display blasts through random numbers but at some known frequency it always lands on the same number (the secret code). When you view through a camera with a frame rate of the known frequency, all you see is the secret code. It's the stroboscopic effect.

If you're interested in the code, I can make that available. Shoot me an email. It's nothing amazing--the coolness is in the physics.

btw, for future work, I think the code could be improved to increase randomness when viewed with the naked eye. For isntance, rather than displaying random digits, illuminate individual LED segments and maintain a constant probability of illumination for each segment.

Short video is below. For the full build description, see the #FridayNightAwesome weekly facebook live from 4/6/2018 in the group: