On Tue, 08 May 2012 23:45:18 -0400, John Gilmer
wrote:


I suspect that the wear items for an electronic ballast will be the
electrolytic caps,as they are in other power supplies and electronic
circuits.

Nothing like good old planned obsolescence. How much would it really
cost the manufacturers to substitute electrolytic caps with somewhat
higher power ratings? I'd gladly pay an additional $0.20 - $0.50 per CFL
or fixture for substantially longer mean time before failure.

Regardless of how good you make the electronics, the fluorescent tube
gradually loses efficiency. The plasma inside the tube will cause
parts of the electrodes to "sputter" off. At the minimum this will
damage the phosphor. There is a "getter" effect whereby the sputtered
metal can trap some of the Hg.

Just like in the old Model T Fords, good design is to make all the parts
so that they reach economic end of life at about the same time.

Within the last 2 or 3 years, the CFLs have become MUCH better. I have
them all through the house and I might replace ONE CFL each month.
Replacement just isn't much of an issue anymore. I use two as "night
lights" where they burn 24/7.

That said, the LEDs are gradually coming into their own. Some of the
earlier consumer LED had a very short life but most seem OK today. One
lamp "fogged up" because, I suspect, a poor choice of plastics in the
construction.

White LEDs are actually fluorescent devices with a UV LED causing the
phosphor to glow. My understanding is that the phosphors are slowly
damaged by the UV light and lose efficiency. Almost all LEDs still use
resister ballast.

Cheap crap uses resistors - good stuff uses constant current source IC
devices

When & if "they" throw electronics into LED lamps, the electronics would
have to be an order of magnitude more reliable than that used for CFLs
simply because the LED itself lasts at least an order of magnitude
longer that an Hg based fluorescent tube.
The single chip LED drivers are VERY reliable. And quite cheap too.