In article ,
Andy wrote:
Andy comments:

I have a number of those small LED flashlights that I got free
from Harbor Freight for visiting the store. They use three AAA
cells in series driving nine LEDs in parallel, with no current
limiting. When on, the drain from the AAA cells is about 160 ma.

As a retired engineer, I made up a little thingy about the
size of a dime which can be inserted in the back between the
battery terminal and the little spring. This inserts a 100 ohm
resistor in series with the AAA cells and drops the current drawn
to about 16 ma.

Since the current draw is 1/10 of an unmodified flashlight, the
AAA cells will last a bit longer than 10 times as long......

The light output is reduced, but not drastically so. All the LEDs
still light and the light output is more than enough to see your
way in a darkened room or read a book by.....

I have modified all my little LED flashlights this way, and all
work about the same.

My "thingy" is a piece of double sided G-10 with a small
1/4 , 100 ohm resistor put in a slot which connects one side
to the other. The shape is like a dime, so it will easily fit
right in behind the AAA cells in the back...

Just wanted to pass this along in case someone here would
like to try it...

Andy in Eureka, Texas

Very, very interesting. To understand how you built it, I'd
sure like to see some photos, maybe even on a "MACRO" setting.

Does seem to me that a dime is pretty thick for inserting behind
one of those AAA batteries.]

And, what's a G-10 (double sided)?


You say "right in behind the AAA cells" ie plural -- if they're
in series, all you need do is put it *somewhere* in the circuit,
ie behind any *one* of the cells? Or am I missing some basic
concept of what you've done?




Question: how did you measure the amps pulled? That is, where
and how did you break the circuit so you could insert the
ammeter (part of a vom)? At least in my 3-AAA led lights
and headlamps, it's a pretty tight fit.

Obviously you have some neat technique that I'd like to learn!


Thanks,

David