4 ms·
You might be able to get a similar effect to the naked eye, if you used a sound wave at/near the same frequency as your local mains electricity, under incandesc
by EvilTerran 15y ago
You might be able to get a similar effect to the naked eye, if you used a sound wave at/near the same frequency as your local mains electricity, under incandescent mains lighting. A harmonic frequency might even work, too.
I recall seeing a tool for fine-tuning vinyl turntable speed that used that form of the trick - it was basically a cardboard "record" with spokes printed on it every (* grabs a calculator *) 4.02deg, so as to appear to be stationary when rotating at exactly 33.5rpm under light flickering at 50Hz. Thought that was ingenious.
- jff 15y agoSure to cause humorous results for us Americans with our 60 Hz mains, if we were to import such a tuner.
- ktizo 15y agoThey often have a 50/60hz switch on them.
- ChuckMcM 15y agoI still have a turn table and it has stroboscopic marks on the rim for just that purpose. :-) Sadly I only have one more cartridge for it and after that, no more replacement needles. I prefer the water and corn starch on a speaker [1] to get standing structures of weirdness. [1] https://www.youtube.com/watch?v=SbTHExJzJXs https://www.youtube.com/watch?v=SbTHExJzJXs
- judofyr 15y agoHere's a slightly more fascinating video of Oobleck (water + cron starch) on a speaker: https://www.youtube.com/watch?v=Yp1wUodQgqQ https://www.youtube.com/watch?v=Yp1wUodQgqQ
- moe 15y agoTechnics turntables have strobe dots on the rim for calibration: http://www.youtube.com/watch?v=XLtlELevKdk#t=0m12s http://www.youtube.com/watch?v=XLtlELevKdk#t=0m12s
- StavrosK 15y agoDamn, so that's what that's for!
- dredmorbius 15y agos/incandescent/fluorescent/ Incandescent (filament) bulbs glow by black-body radiation as the filament heats. Mains cycles are too short for the bulb to flicker (though you can get interesting effects on slower, ~2Hz or thereabouts, voltage fluctuations). Fluorescent and LED lighting actually flicker multiple times per second, though this can be tuned somewhat. If you remember CRT displays and monitor flicker, the problem wasn't so much the flicker rate of the monitor, but the interference in rates and timing between your monitor and the overhead office fluorescent lighting. Setting refresh to anything other than (and preferably above) 60Hz (US) would resolve this.
- lloeki 15y agoAren't LEDs fed with DC? If so they would obviously not flicker but I'll admit not cracking my LED bulbs open just to see, as they're expensive enough.
- meatmanek 15y agoLEDs are generally fed with DC, as current only flows in one direction, but they flicker as the power coming into them fluctuates -- the more ripple, the more flicker. Cheap LED holiday lights don't even bother rectifying the AC voltage across the lights, so they are only on for half the cycle, giving them a very noticeable flicker. It's especially apparent as you scan your eyes past them. In contrast, incandescents allow current to flow both directions, and will glow for a little while after current stops flowing, so they don't appear to flicker on 60/50hz mains current.
- dredmorbius 15y agoLEDs are DC. What I've observed in certain applications, particularly LED taillights/brake lights, is a flicker pattern which I suspect is either an AC/DC conversion artifact, or a brightness regulation. I find it quite distracting. It's also fairly well known that LED's response to voltage variation is fast enough to be of concern in highly secure data environments. Demonstrations have been made of reading line signal from modems, and even Ethernet and other high-bandwidth networking equipment status/indicator lights.
- 15y ago
- js2 15y agoThe turntable from A Clockwork Orange (Mitchell "Transcriptor" - my dad owns one) has a strobe and a marked wheel for adjusting its speed. See the second image - http://www.1stdibs.com/furniture_item_detail.php?id=333935 http://www.1stdibs.com/furniture_item_detail.php?id=333935