Trevor Wilson wrote:

**The full brightness thing is not associated with the electronics. It's an
issue with the gas in the tube and, to a lesser extent, the phosphor
coating.

So why do some CFLs keep the brightness more constant than others?

Don't sweat it anyway, LEDs will replace them in most applications very
soon. I've been mucking about with a couple of these recently:

Aren't LEDs also temperature sensitive? Because I had a hot chassis
TV with optical couplers for the composite video and audio, and the
picture brightness & contrast would change slightly when it warmed
up. There were also pots to adjust the couplers.