Cory's WRP-130 Ooops LED Instruction........greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread
Kosky's girl and her braces will have to wait.........http://www.kiyoinc.com/current.html
-- kevin (email@example.com), October 12, 1999
Wow, I have arrived! My comments got into a WRP! Yeah bay-bee! [chuckle]
With all seriousness though, I've started to sell the LED driver and array combos I've created and all they need is a case of whatever sort the user's needs require, and a power source. (If you're curious, E-mail me as I still have four sets left.) Plug the parts together, hook to 12 volts DC, and go. No soldering (except for the power leads), no reinventing the wheel, just plug together, connect power, mount in case, and use. Should be great for the creative types that aren't electronically inclined.
That aside, the white LED info on the WRP should help out quite a bit. I'm going to post a pros and cons article I cooked up regarding white LEDs so everyone will have it. That'll be up momentarily. (Gotta find the file, ah, there it is...)
-- OddOne (firstname.lastname@example.org), October 12, 1999.
With Y2K coming at the expected one-second-closer-every-second rate, those that are prepared to do so mentally are preparing for problems in a more physical sense. Some folks are going or will soon go off-grid, severing ties to the power grid in favor of electrical independence. As a result, white LEDs have become objects of interest from both the Y2K prep crowd and the off-grid folks for extremely low- power lighting. This article will discuss the pros and cons of white LEDs in lighting applications.
My information is derived form real-world use of my own white LEDs. I also have a website up that is devoted to white LEDs, their uses, and information. References to this website might appear in the article, so I'll give you the URL now:
OddOne's White LED Information: http://www.geo cities.com/SiliconValley/Bay/4397/
First, the positives...
- White-LED flashlights have much longer usable life on a set of batteries than an equivalent incandescent bulb does. A LOT longer. Take good care of the LED-based flashlight and it'll serve you for a very long time, especially in the case of the aluminum- bodied ones that have such a durable casing. Just don't drown the light (read: Drop it in water) or trash it, and take care to check the batteries for leakage, etc.
- Dramatically increased toughness and impact resistance. (Ever had a flashlight bulb go south just from the light being dropped? I have. Trashing a bulb could be a very bad thing in a post- SHTF world, especially if that was your last bulb.) If each LED is properly mounted with a spacer to help take the shock, white LEDs can survive very severe drops. Spacers cost seven cents in single quantities from Mouser Electronics, and a 1/4" 4-40 (non-threaded) nylon spacer works very nicely as well and can be procured from small hardware stores for a dime or less each.
- The light tends to be more uniform in color balance, although this seems a bit odd at first since it looks to the eye to be bluish-white. Fewer dark spots as well. The light tends to taper off smoothly off-axis. Shadows are generally crisp and well-defined. Generally superior in terms of usability than incandescents.
- The light is visible for a LONG way off (three to five miles in my tests, in clear conditions at night) and reflective surfaces are visible for two miles or more with no source other than the LEDs. Street signs glow as if self-lit and car reflectors shine like they were lit up from within from a long way off.
- White-LED lights also use a lot less current than incandescent bulbs for the same luminous output at spot's center, stretching those batteries a lot farther. Use Lithium batteries with their ten-year shelf-life, or NiMh (NOT NiCd!!!!) rechargeables with a solar charger and your light could last longer than your possession of it. (Take that as a hint to safeguard it if TSHTF. Others may see it and want it. I planned to build a few small six-LED units for barter items.)
- With some creativity, you can build really small but really effective flashlights. One of my LED projects, a six-LED flashlight, is about 3" long and an inch in diameter. For my next white-LED trick I planned to build a three-LED light using a single 12-volt 23A or equiv. battery that would be an inch square and half an inch thick. A postage-stamp light. (Photos of the converted flashlight are posted on the White LED Information website, mentioned above.)
- The best advantage is that they are really easy to work with if you have a rudimentary understanding of electronics. Just keep the voltage below their maximum rated limit and they'll last for a LONG time. (Nichia's model # NSPW500BS white LED has a 100,000-hour rated lifetime, which is about 11 YEARS of continuous operation.)
Now, the negatives...
- White-LED lights need higher voltages than incandescent, although they stretch the power usage much farther. (My six-LED flashlight, which was converted to LED from incandescent, runs on two A544/PX28A/equiv. 6-volt alkaline batteries for about twenty hours total. The two batteries combined are almost the size of a single 'AA' battery. They are widely available at Radio Shack, Wal- Mart, K-Mart, etc.)
- White-LED lights need a certain number of LEDs to be effective. I'd not use less than three LEDs for reading at close ranges, and six LEDs can produce enough light to use for moving around with comfortable levels of visibility. Single LEDs on lithium watch batteries (such as those little keychain jobs like Photon lights) are good for very basic applications but that's about it. So, if you get a white LED flashlight, I'd strongly recommend getting one with six LEDs if you can find one. (Again, my six-LED flashlight, which was converted to LED from incandescent, is bright enough to read text by from several feet away.)
- White LEDs are visible for a long way off, which could be a problem if you are being pursued or need to approach a potential target or meal with stealth. They just seem to "jump out" to the eye, more so than typical incandescent flashlights. Their output has that cool fluorescent "feel" to the eye.
- For brighter light, you'll need to drive them with a high- efficiency driver to get the most out of your batteries. See my LED driver page for schematics for a basic timer-chip-driver that can push hundreds of LEDs at once with minimal drain. (I now have drivers and arrays ready-made for sale; contact me via my posted E-mail address for the specifics.) You'll need a decent level of hobbyist- type expertise with electronics to build one, but it'll be well worth it. My second LED driver prototype drives 36 white LEDs off eight 'AA' batteries. (The driver and LED arrays are now available for purchase; visit the White LED Information website for more details and pricing.) I've had the same batteries running it for a few months now. It consumes less than two watts of power at 12 volts at full brightness and you can see it for MILES...
- The LEDs themselves are static-sensitive. Small static charges can toast them. Proper handling precautions for anti-static semiconductors are required to prevent damage.
- The biggest downside is cost: They are REALLY expensive. Nichia wants $ 1.60 EACH IN THOUSAND QUANTITIES for theirs! And that's direct from the manufacturer. If you'd like to buy plain LEDs to play with, wait for the next LED bulk-buy and get in on it; it'll save you a LOT of $ over buying them in small quantities from distributors.
Hope all that info helps out everyone that wanted to know! If you would like more detailed info, want to buy or build a driver, or want to know a few sources for the lights, E-mail me. I have PLENTY of info.
OddOne, who's spent too much time tinkering with white LEDs...
-- OddOne (email@example.com), October 12, 1999.