Re: d-day

["Jeff Volp" <JeffVolp@xxxxxxx>]

There are many fixtures that would not accept the older CFLs without some
modification.  You may remember the hoop extenders that were included with
some of the early CFLs.  Most of today's commodity CFLs are physically much
smaller with bases similar in size to equivalent incandescent bulbs.

Low power factor results from a capacitor-input power supply that is only
drawing current near the peak of the waveform (which also happens to be away
from where X10 signals are transmitted).  The small bases used in today's
CFLs make it impossible to squeeze in the 175V+ electrolytic capacitor
required for direct line rectification.  So these newer units use a
switching pre-regulator on the raw rectified AC input.  That pre-regulator
runs essentially over the entire waveform, resulting in a much higher power
factor (and also noise radiated in the X10 transmission window).

I'm amazed how cheap semiconductors have become.  It may very well be
cheaper to use a switching pre-regulator than the large high-voltage
electrolytic capacitor needed for direct line rectification.  The XTB filter
capacitor costs almost twice as much as the high power MOSFET used in the
transmitter output stage.  It wouldn't surprise me that the pre-regulator
design actually costs less.  And the smaller physical size means a larger
potential market for these commodity CFLs.

Jeff

"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
news:476e93ac.444169625@xxxxxxxxxxxxxxxx
> Jeff, I'm not at all sure what you're referring to or how your "large
> capacitor" or X10 compatibility is pertinent to whether or not CFLs have
> low
> power factors but this is taken from the Wikipedia article on Power
> Factor.
> You can find essentially the same analysis and numbers at several other
> web
> sites having to do with SMPS design. And, people have posted Kill-A-Watt
> measurements of CFL PFs here that were in the 0.61 area. I doubt that low
> cost commodity producers of CFLs are going to voluntarily increase cost by
> using active PF correction. If you read my original post on this, I said
> "if
> uncorrected", most CFLs with will have low PF - what was unstated is that
> most CFLs now use SMPS and will need PF correction - I did not say that
> all
> CFLs must have low PF.

(other stuff snipped)