Well since this thread is still kicking.... I installed a new oven/range hood and exhaust fan, and light. The light switch has a "night light" setting which puts a diode in series with the lamps. I installed 2 CFL's and just had to see how they would react with half wave pulsating DC. I thought they would work, and I was right. I can see some flickering but they aren't very dim. One of these days I'll measure the current with and without the diode in series. I don't leave them on the pulsating DC, in fact one of these days I'll jumper the diode so I can't leave it on that way by mistake.
In general, most integral-electronic-ballast CFLs, especially non-dimmable ones, have a bridge rectifier - a basic circuit section having 4 diodes.
If you give such a CFL DC (pulsating or otherwise), it draws its current through only 2 of these 4 diodes - making those 2 diodes produce almost twice as much heat as they otherwise would. This is partially counterbalanced by the other 2 diodes making little or no heat at all, but there is still the matter of 2 diodes conducting twice or almost-twice as much current as they would in "normal use".
I give chance of frying these diodes to be low, since in the few times I dissected CFLs these diodes appeared to me to be 1-amp ones (or worth at least half an amp as being part of an integrated-circuit bridge rectifier appearing to me nominally rated for 1, maybe 1.5 amps).
One thing to worry about is ability of these diodes to conduct a given quantity of current being impaired by the heat coming in from elsewhere nearby - it appears to me that "the numbers usually add up OK" - but
*only usually*.
If I was going to bet my house on a CFL here not burning it down, I would *at least* restrict myself to doing this with UL listed ones (in USA) of "Big 3" brands that have more at stake in terms of liability, and even then I fear that I might need some "legal budget" if things go kablooey.
And, if I was going to use a fixture having a dimming diode with a CFL hardly dimmed by the diode, I would bypass the diode. Modifying the fixture in such a way technically invalidates UL listing of the fixture and increases your liability if things go kablooey anyway... If the fixture has both dimmed and undimmed switch settings, I would use only undimmed with the CFL - but you still may need "lawyer power" if things go KABLOOEY because your fire insurance company's lawyer can argue that you had the switch on "dim" and turned the switch to "full" after the CFL became obviously mortally wounded - a bad thing to do since the worse diode overheating problems from DC or pulsating DC tend to get worsened by going back to AC after a diode or two got toasted by use of DC.
Or possibly, not. Apparently there's a problem called "droop" when they try to increase the intensity of LEDs - efficiency drops - and it's already not quite as good as CFLs on the newer 1 watt and larger LEDs. Color ... maybe. Price ... maybe a little. But it seems the technology is currently stuck.
I just got a couple of the 23 watt and 40 watt candelabra base CFLs, put in one 40 watt - and it was almost too bright, compared to the incandescent it replaced. That's in a fixture. Haven't put them yet into the chandelier, we'll see how that goes esthetically. Fortunately we already removed the dimmer!
Cree XP-G has definitely more efficiency and apparently less droop than other white LEDs of similar current ratings. The bare LEDs just became available at Digi-Key a couple weeks or so ago.
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