- 2024
- Jan
- 20
Magic Eyes - glowing green magic from the vacuum tube era.
One of the most interesting and accessible pieces of tech that came out of the tube era is the Magic Eye. A phosphor cup (or target) is illuminated with an electron beam, and a grid allows or blocks that electron beam to “open” the eye. It’s a device that can indicate changes at the speed of the phosphors used, and it found it’s way into all kinds of devices - radios as tuning meters, signal tracers as signal indicators, capacitance checkers as a quality meter - anywhere a fast visual change needed to be shown to the user.
These two signal tracers, one branded Knight, the other Eico, have eye tubes as their wattmeter and signal indicators. The Eico’s eye is so bright it overloads the camera, while the Knight’s eye shows much more use in it’s dimness.
While eyes fell out of favor as meters, VFDs, and other electronic indicators came into their own, they still remain one of the most striking devices in mid-century electronics.
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