On opening my Osram 3W fluorescant light, I found a 500 ohm pot. When twiddled one way, it makes it brighter, when twiddled the other, dimmer. Twiddled to a position at about 11:00, it uses 0.32A, rather than the normal
0.82A. It's dimmer, but still a good task light, and will now last about six hours, not two on NiMH cells, and its run-time on alkaline should be considerably extended. Don't turn it all the way anticlockwise, or something starts smelling hot.