Re: [Phys-l] led flashlights

[Steve Highland <shighlan@uslink.net>]

I haven't gotten around to trying to do it myself, but I've wondered for a
long time how well an LED flashlight would work for making a simple strobe
light.

All you'd need is a pretty simple circuit to flash the LEDs at an adjustable
rate.  Has anybody tried this?

Steve Highland


> As an aside, you will find that batteries last much longer in LED flashlights
> than in comparable incandescent bulb flashlights.  I've got one 3-LED cheapie
> flashlight that uses 3 AAA cells.  They last at least four times as long, and
> the light stays bright throughout battery life.  The brightness drops sharply
> near the end of battery life, rather than gradually.
>
> Mark Shapiro
>
>
> -----Original Message-----
> From: phys-l-bounces@carnot.physics.buffalo.edu on behalf of Eric Lane, Lane
> Sent: Wed 3/5/2008 6:49 AM
> To: phys-l@carnot.physics.buffalo.edu
> Subject: [Phys-l] led flashlights
>  
> 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
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