0

August 15, 2011 AT 2:01 pm

Simulating Magic Eye Tubes With Spinning LEDs and Simple Electronics

So-called “magic eye” tubes are display devices, which indicate signal level by the projection of wedge-shaped shadows on a glowing view screen. They were developed in the 1930’s for use as tuning indicators in radio receivers, and as alternatives to the then-expensive-to-manufacture meter movements.

Because they haven’t been produced in decades, and because they degrade and wear out with use, the supply of functional eye tubes is dwindling. I thought there might be value in coming up with a potential substitute– something that acted like an eye tube that could replace them in applications like antique radio restoration and general experimentation.

It turns out that convincing eye tube behavior can be simulated with one or more LED’s mounted on a rotating disk. The electronics to drive the LEDs amounts to little more an an op-amp, a transistor, and some timing components.

This video demonstrates the appearance of a real eye tube in operation, and introduces the principles involved in simulating one through electro-mechanical means. The video shows that the display generated by the electro-mechanical equivalent can be fairly convincing.


Check out all the Circuit Playground Episodes! Our new kid’s show and subscribe!

Have an amazing project to share? Join the SHOW-AND-TELL every Wednesday night at 7:30pm ET on Google+ Hangouts.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Learn resistor values with Mho’s Resistance or get the best electronics calculator for engineers “Circuit Playground”Adafruit’s Apps!


Maker Business — HOW ANKER IS BEATING APPLE AND SAMSUNG AT THEIR OWN ACCESSORY GAME

Wearables — Spooky liquids

Electronics — The deets on Electret Microphones

Biohacking — Mind-Controlled Spermatozoa

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !



1 Comment

  1. That’s a pretty cool project. It definitely inspired me to put the microcontrollers up for a week and get back to basics.

Sorry, the comment form is closed at this time.