In article , Art Todesco wrote:
Don Klipstein wrote:
In ,
wrote:

On Apr 27, 2:51 pm, (Don Klipstein) wrote:

I have this sinking feeling that dimmable screw-base CFLs at least
sometimes lack provision to have their filaments maintained at a proper
temperature when they are dimmed. I would expect some compromise in life
expectancy with severe or moderately severe dimming.

One scheme mentioned a lot in some thread in sci.engr.lighting earlier
this year is to have two sets of lights in a room - one for bright
lighting and another for dim lighting.

- Don Klipstein )- Hide quoted text -
There is no filament in a CFL.

All fluorescents except cold cathode types have a filament at each end
to use as an electrode. They have a coating that gets sputtered
(effectively evaporated), and much more rapidly if they are not at the
proper temperature. When that coating is gone, the fluorescent lamp does
not work too well (often not at all) anymore.

- Don Klipstein )

Kind of a matter of semantics. CFLs usually don't have a filament as
in the long tubes. They do have an electrode at each end. The
filaments in the standard tubes are used as heaters to help in
starting. CFLs use a higher voltage that don't require the
pre-heater.

In instant-start hot cathode fluorescents including instant start
CFLs, the electrodes are still in the form of filaments.

Also, many hot cathode CFLs are not true instant start but "program
start" or "trigger start" ("rapid start" with filament heating current
reduced once the lamp gets started). The filaments actually get
preheated in those.

Cold cathode CFLs don't have filaments, but few CFLs are cold cathode.
I have never seen Home Depot carrying more than one cold cathode model -
the 3 watt N:Vision one. And I was there yesterday.

- Don Klipstein )