Xref: utzoo misc.consumers:4751 sci.electronics:2889
Path: utzoo!mnetor!uunet!husc6!linus!philabs!ttidca!hollombe
From: hollombe@ttidca.TTI.COM (The Polymath)
Newsgroups: misc.consumers,sci.electronics
Subject: Re: fluorescent lights and my brain
Message-ID: <2427@ttidca.TTI.COM>
Date: 29 Apr 88 20:01:12 GMT
References: <530@scourge> <1182@ssc.UUCP> <1532@dataio.Data-IO.COM> <1143@neoucom.UUCP>
Reply-To: hollombe@ttidcb.tti.com (The Polymath)
Organization: The Cat Factory
Lines: 29
Keywords: eyes head ache electricity

In article <1143@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes:
}We connected a photo cell up to the input of an oscilloscope just
}to be sure.  It would appear that fluorescent lights flash 120
}times per second.  That is to say, one pulse of light is emitted
}for each 1/2 cycle excursion of the 60 Hz waveform. ...

}... What would help would be to obtain a solid state ballast unit as is
}used in recreational vehicles.  The ballasts operate at high
}frequencies, thus the flashing is less objectionable.
}Unfortunaely, some people find the several KHz whine just as
}annoying as the 120 buzz emitted by conventional lighting.

All of the above is overlooking a rather important physiological point.
According to my psych. course in Sensation and Perception, under ideal
circumstances the maximum flicker rate detectable by the typical human eye
is about 60 hz.  That's why projectors in movie theaters open and close
their shutters 3 times per frame, yielding an undetectable flicker rate of
72 Hz (and why movies were called the "flicks" before they discovered that
trick).

Therefore, if fluorescent tubes strobe at 120 Hz, they can't be causing
your headache problems.  Your eyes are physiologically incapable of
detecting the flicker.

-- 
The Polymath (aka: Jerry Hollombe, hollombe@TTI.COM)   Illegitimati Nil
Citicorp(+)TTI                                           Carborundum
3100 Ocean Park Blvd.   (213) 452-9191, x2483
Santa Monica, CA  90405 {csun|philabs|psivax|trwrb}!ttidca!hollombe