17-March-2008, 07:57 AM
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Senior Member
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Join Date: Mar 2004
Posts: 9,718
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Quote:
Originally Posted by neilzero
Floresent tubes drop to about half brightness 120 times per second. About half brightness for USA television, but 60 times per second. Computer screens, and compact floresents lights have refresh rates up to about 200 times per second, so all behave like a strobe.
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CFLs usually have electronic ballasts these days. So do modern tube installations:
Quote:
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An electronic lamp ballast uses solid state electronic circuitry to provide the proper starting and operating electrical condition to power one or more fluorescent lamps and more recently HID lamps. Electronic ballasts usually change the frequency of the power from the standard mains (e.g., 60 Hz in U.S.) frequency to 20,000 Hz or higher, substantially eliminating the stroboscopic effect of flicker (100 or 120 Hz, twice the line frequency) associated with fluorescent lighting (see photosensitive epilepsy).
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