For a red flashlight use a high brightness red LED and a 22 ohm to 44 ohm or higher 1/4 watt
resistor in series with 2 Alkaline Energizer D cells. The LED and resistor can be purchased
from Radio Shack. Use a jumbo Super-bright Red LED Cat. No. 276-066 (5000 mcd) or
Orange Cat. No. 276-206. (12000 mcd). This combination would give about 1.5 to 3 months
of 24 hr/day on-time of useful light. Variation on useful light would come from which resistor
was used, the original age of the cells and what level of light is still considered useful. The
amount of useful light goes down almost linearly with time.
Some times LED task lights are called head lamps, because they are worn on the head. If you were to take one of the LED's below, say the Orange Cat. No. 276-206 ($3.99) or Red Cat. No. 276-086 ($2.49) and attach it to a hat or headband so that it would points to the most useful forward, slightly down, direction, then run a thin flexible wire down to a 2 D cell battery holder Cat. No. 270-386 ($1.59). Add a push button switch cat. no. 275-617 ($1.89) in series. Use black electrical tape and attach the battery holder and the switch and the 22 ohm resistor to your belt or a separate belt. Wire all components in series.
The result is a task light that takes no hands to point and which will give about 3 years of useful light if one averages about one hour/day of use. If one uses less time the life goes up proportionally. Could be used in your shelter to repair or inspect dark areas or for backpacking on foot. Could keep one from stepping where one shouldn't at night. This concept of using LED's in a head lamp will sooner or later be sold as a commercial product. Right now I know of no such product you will need to make it. Of course one would look like a red eyed Cyclops monster to some. Other color LED's are also available if one likes yellow, green, blue or white instead. Most other colors do not put out as much light as the orange one. Total cost to make this is about $8 not including battery and wire. A good science project for your kids to make between now and the pole shift time.
Offered by Mike.