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|We didn't ask to be a radio! Why do you hate us?|
Schematic posted below, if you want that badly to emotionally scar your children. The really handy reader might incorporate an aux in jack, so you can listen to your own selections on the Radio Face - you know, Rammstien, Slipknot and Raffi.
UPDATE - Alert Reader Bill Beaty is a big fan of "magic eye tubes", something I hadn't heard of, not even from any of Dad's lengthy orations on engineering. Bill's explanation of MET's was so thorough, we have added it to the post. Thanks for filling in the blanks, Bill!
"They were little tiny one-pixel CRTs built into radiotube-sized, well, radio tubes. High voltage, electron beam, glowing green phosphor with moving light patterns (responds to waving around-magnets just like old tee vee screens did.)
The best part is how they worked. If you were standing on the moon, in vacuum, and someone beamed an electron spotlight at you, your electricity shadow would have the usual shape, but its size would change depending on the amount of electric charge on your body. Unlike charge would attract and focus the electron beam, making your shadow shrink down to miniature size. In the Magic Eye tubes there was a thin wire casting an "electricity shadow." If the wire was negative charged, it repelled the passing electrons, and its black electron-shadow on the phosphor screen would expand wider. It's an inexpensive animated bar-graph which instantly reponds to a voltage signal. Bet it started out as Nazi Super Science, stolen by the Allies during Project Paperclip. :) Think about it ...the perfect futuristic green-glow device for vacuum-tube Bakelite instrument panels on German antigravity disk aircraft in WWII. Hey, "Ozone and Hot Insulation" type of incense sticks? I'd buy 'em."