What happened to the postings?

[Jeff Engel]

There has never been such a long idle period. I'm sending this posting
just to see if my access settings are still working.

 

[TKM]

There has never been such a long idle period. I'm sending this posting
just to see if my access settings are still working.

Your settings appear to be working, Jeff. There's been a bit of new
information regarding the flicker topic. DOE backed off of their 150 Hz.
requirement and returned to 120 Hz. I think it was because of manufacturer
feedback saying that it was costly to modify the systems without evidence of
a visual benefit. Perhaps others know more about that aspect.

In any case, there is now an IEEE Standards Group looking into the matter.
See:
http://grouper.ieee.org/groups/1789/

Terry McGowan

 

[TKM]

That makes sense from the mfgs point of view. 120 Hz is derived from a
60 Hz system*. Any higher frequency is going to need its own clock. And
then there could be problems with intermodulation between that clock and
the line frequency that could make things worse. O more expensive.

* Seeing as how the EU uses 50 Hz, the flicker problem (at 100 Hz) would
seem to be worse over there. What's their level of concern?

That's an interesting question. I've always been more bothered by flicker
in 50 Hz countries via the TVs and magnetically-ballasted fluorescent
lighting; but I can't speak for anyone who experiences it on a more-or-less
permanent basis.

The first research papers that I saw that involved lighting did come from
the U.K. though. The classic one which I mentioned previously and still use
is: Human Sensitivity
To Flicker by G.W. Brundrett. Lighting Research and Technology Vol. 6, No.
3 (127-143 (1974).

Terry McGowan