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Re: Optical Communication



I just measured several of them -- they range from 20 to 30 KHz.

bc

The osc. is two windings of three turns and another four T on a ferrite
torroid. A conventional, in appearance, very small transformer is the ballast
-- one winding, one Ohm dc res. core is also ferrite.

brian whatcott wrote:

At 14:58 4/5/01 -0500, Mark Kossover wrote:
Howdy-

A couple of weeks ago, I attended the NSTA convention in St. Louis.

/snip/

Another interesting effect is that the solar cell can be brought near a
monitor. The monitor's flashing creates a distinctive buzz on the speaker.
Different refresh rates create different pitch hums.

Marc Kossover
mkossover@newman.k12.la.us

Mark's set up reminds me of a flicker photometer I set up when
I had a bee in the bonnet about flicker from fluorescent lights
provoking eye strain or headaches. People who sell these
lights are not specially forthcoming about their flicker contribution.
I notice that some fittings using electronic power supplies are
reputed to flicker at a much higher and less bothersome rate.

Though I haven't checked them out, the folded fluorescent tubes
on incandescent style screw bases may be in this category.

brian whatcott <inet@intellisys.net> Altus OK
Eureka!