The ones I remember didn't need batteries.
Am I thinking of something else?
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jonbob loves you, Fri 13 Apr 2018, 23:17,
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en.wikipedia.org/wiki/Test_light - if he's gonna go that far to detect voltage via body capacitance he may as well go the whole hog and build a solid state theremin to make freaky noises with: en.wikipedia.org/wiki/Theremin#Operating_principles
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artifus is doing it all wrong, Fri 13 Apr 2018, 23:25,
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That's them.
I'd always though they were crude things with filament bulbs in them. Now I see they're crude things with fluorescent bulbs in them.
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jonbob loves you, Sat 14 Apr 2018, 1:42,
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It's a neon bulb which is a gas discharge lamp
Fluorescent lamps generate the final light with a phosphor that converts one wavelength into another.
(apologies for the pedantry!)
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tarka_dall Like normal dall, only a bit more spicy, Sat 14 Apr 2018, 7:18,
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