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Construction Notes:

1.  Don't use Radio Shack circuit board.  It's full of nasty chemicals.  I ended up replacing it with a piece of Formica countertop that I got as a sample at the hardware store.  Another brand of circuit board made out of fiberglass would be better, but the Formica worked fine.
1A.  Tie wires to circuit board with string and wrap circuit board in plastic sandwich wrap for protection.
2.  Radio Shack 10k linear potentiometer with optional switch.  It's really big, but it fits.
3.  Remove stock flashlight switch, spring, and bulb holder.
4.  Make adapter plate to hold dimmer.
5.  File away small tabs in lens ring so it can be threaded on without twisting the reflector.
6.  Use Radio Shack 2AA battery holder with snap connector.  Solder longer wires onto snap connector.
7.  Pack with cotton from pill bottle.
8.  Use string to hold LED assembly to reflector.
9.  Connect leds in parallel to Vout without using dividing resistors.
10.  Put a fender washer on the back end of the flashlight body to cover the hole, and then a couple of nylon washers between the fender washer and the knob to form a bearing surface for the dimmer knob.  This will hold the dimmer tight and give it a smooth feeling when turning.
11.  The dome top on an led focuses the light into a center hot spot.  Grinding the led flat and polishing it with toothpaste removes all the beam characteristics and turns it into a light pattern similar to a fluorescent bulb.
12.  Add a light green or yellow filter to soften the light color.

Features:

Nice diffuse light.
Lights up dim for use in the middle of the night.
Fits in a jacket pocket.
Parallel leds (not the best, but okay)
Regulates voltage.
Uses Nimh or alkaline batteries.
Takes alkaline batteries down to .7 volts so it can run on discarded batteries from other devices.
Big parts for easy assembly.

Long Term Test Results:

It was too bright at the lowest setting for the middle of the night.  I changed the voltage range so the dimmer would go from 2.4 volts to 3.5 volts.  Much better for night vision.  R2=11k, R1=19.5k, Dimmer range = 0 to 10.5k.