The newer led flashlights apparently have a voltage multiplier circuit along with a voltage regulator that boosts the battery voltage up to what the leds need. This means that you can use old batteries to power the flashlight and get almost the same intensity as with new batteries, although they don't last as long. I find this to be a great use for my used AAA bateries that are too weak to power my calculators. Old batteries work in small radios but they last so long that i've accumulated a small box full of weak, but still usable batteries. Mag-Lights@ with a tungsten filament that use AAA batteries also work well but the light starts dim and gets dimmer as the battery is used up. Leds keep the light level high for a shorter time. Great! I found mine at Harbor Freight on sale for under $2 apiece (not an advertisement, just a fact.)
Prof. Eric T. Lane eric-lane@utc.edu
Physics Dept. 2352 423-265-7804
The University of Tennessee at Chattanooga 37403-2409