0

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.


Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 8,500+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

CircuitPython – Python on Microcontrollers is here!

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!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/


Maker Business — Rethink Robotics closes shop. Long live collaborative robots #makerbusiness

Wearables — Cleaning is key

Electronics — Serial overkill

Biohacking — Biohacking Resources – Books, Talks and Podcasts

Python for Microcontrollers — CircuitPython @ Hackaday SuperCon #ICYMI @circuitpython @micropython @ThePSF #Python

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.