White LEDS and buying in bulk. Pooling orders together...greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread
OddOne's back on the attack regarding white LEDs for whatever lighting purposes you might have in mind.
Since this is a long post, I sprinkled anchors in it so you can jump to specific points (I hope they work!):
Nichia's Pricing Schedule
Terms of this bulk-order
Getting in on the bulk-order
In a previous thread I proposed getting a group of buyers to pool smaller orders into one massive order and buying in bulk directly from the manufacturer. So far there have been several positive responses for 10, 20, 25, even 50 pieces at a whack. Therefore it's probably a good idea to roll with it and see if we can get an order together. Here's my plan on how to do the deed. Note: Since this plan isn't set up for international orders, I'm afraid folks outside the US will need to hunt down sources more lcoal to them. Also, if you live in Alaska, Hawaii, and US commonwealths like Puerto Rico, you may or may not be able to get in on this deal depending on shipping costs, etc.
Just for clarity, my offering to coordinate and place a bulk-order is strictly as a service to the Y2K preparedness community. You folks have helpd me GI and helped me get my family and friends at least aware so it's a small step in saying thanks. My only benefits from this is the ability to get the quantity I want (50-100) for less $ per piece. I am not marking up the per-unit costs either. The per-piece prices I will quote are straight from the info I received from Nichia. All I ask in return is that each participant pay their part to ship the jokers from Nichia to me and then me to them.
The unit to be ordered is the one with the highest light output and correspondingly the tightest beam angle. The specs on the Nichia NPSW500BS white LED are as follows (typed from the spec sheets):
Package size T-1 3/4 (5mm) standard dome-top. Water-clear. Half angle 20 degrees from center (You should get a spot about 1.5-2 feet wide on a wall 10 feet from the LED.) Intensity (minimum) 2.0 cd (cd = candlepower) Intensity (typical) 4.0 cd Forward Voltage (operating voltage) 3.6 V typical, 4.0 V maximum Forward Current (operating drain) 30 mA maximum constant, 100 mA maximum pulsed (assuming a pulse width <= 10 ms and duty cycle of 10%) Reverse Voltage 5 V maximum Operating temperature -30 - +80 degrees Celsius
If you want scans of the specs page, chromaticity diagram, directivity angle diagrams, and/or characteristics charts, let me know as they sent me about ten pages of crap (read: hgihly technical info) on them.
Total costs for each order would be the per-unit cost for the LEDs based on the total we can order times the number you want, plus part of the shipping from Nichia to my business (divided among the orders combined into this one), plus the shipping costs from my business to you directly. To explain, let's say the total order was 1,000 LEDs among ten people, and you wanted a hundred of them. Nichia wants $ 1.60 per at that number, so your cost would be $ 160.00 for a hundred LEDs. Since they want about ten bucks to ship up to 2,000 units and ten people pooled orders together, your part of that would be a tenth of ten bucks. (A dollar. Wow.) Add an additional $3.20 for Priority Mail (while it's still running why not use it? If you'd want to use other methods, let me know although your costs will vary accordingly. I have a FedEx account so if you want them REALLY fast that can be arranged...) to ship from me to you. $160.00 + $1.00 + $3.20 = $164.20 your cost for a hundred. (Let's see you beat $1.642 per piece for 100 pieces of these things from a supplier! If the whole order is large enough this will represent a HUGE savings.)
Now, how to order and pay for it. They have to be paid for in advance. I can't front the $ for that many at once without help. So, when we get the numbers all lined up on who wants how many, I'll let each person know their totals. Also, they won't take credit card payments therefore I can't take credit card payments for any part of it. Send me the $ in whatever form (although I'll have to hold the whole order up until all personal checks clear, so a postal money order would be the fastest way) and it'll be placed in a pool for this purchase only. This protects me from losing a lot of $ and getting stuck with a lot of LEDs due to changed minds, etc. I'll draft up a simple sales contract that states that you're fronting $ for the purchase of LEDs and I'm acting as an order agent in your behalf to the manufacturer. This step protects you from any underhandedness on my part (although that's not how I do business. I have a reputation for honesty I'd like to maintain, thankyouverymuch.) This little order-pool project runs VERY close to actual costs, so there should be very little if any leftover funds. I'd like to keep the excess (which will probably only be a few dollars given the zero profit margain and absence of per-part markups) so I can show the accountant SOMETHING at the end of the year (if there's any such thing as an accountant. ::grin::) This would be my only profit from this exercise. If it's nothing, no biggie, breaking even would be perfectly acceptable.
As soon as the shipment hits my door I'll rebundle them according to the orders and ship them out within the next two business days. ETA from order placed to your part hits your door should be about ten business days, give or take. (This assumes there isn't a big backlog on the white LEDs. If there is, this timeframe is naturally going to slide.)
One last thing. Nichia's price schedule is as follows on these...
Quantity Price per LED 1 $ 8.00 (Yikes!) 10 $ 6.00 50 $ 4.00 100 $ 2.80 (Now we beat Hosfelt, etc.) 500 $ 2.20 (Likely price we'll end up at.) 1,000 $ 1.60 (This would be good to reach.) 5,000 $ 1.40 10,000 $ 1.20 50,000 $ 1,00 100,000 (!!!) $ 0.80 (Great per-piece price but that's $80,000 worth of LEDs!)
Obviously it'd be best for everyone if we have enough orders for enough LEDs each to reach a thousand. That'd take 20 people at 50 LEDs per. If we have a large number of small-quantity orders (10 or so each) join the fray that'll help as well.
Now for usage.
At 4 candlepower each (typical), these little jokers are bright. Their light is similar to a short-arc xenon light in color; it's white but leans toward the bluish end of the spectrum. This is due to their construction, which is a light-blue color that excites special phosphors bonded onto the LED chip. If this bugs you, slip in a Radio Slack orange-red superbright LED (their part number 276-206, $ 3.99) to balance the color out a little more. Three in parallel could be directly wired to the betteries in a 2-AA flashlight such as mini MagLite. The reflector can be removed since the LEDs have their own built-in. (That's why they have a 20-degree half angle.) I might be able to create an adapter board that would retrofit a Mini MagLite flashlight to LEDs by a simple "remove reflector/bulb and plug board into bulb holes" process. (If this sounds appealing let me know.) Seven LEDs should cluster densely enough to fit a Mini MagLite style flashlight.
The specs mention that it can take 3+ times as much current when pulsed. Pulse-operating LEDs also allows driving them at different duty cycles, which allows you to dim or brighten them accordingly. A simple pulse-width modulation driver can be built for $20 worth of parts from Radio Slack. This simple PWM driver can pump a couple dozen LEDs at once from one source and allow variation in brightness (and correspondingly the current drain on your batteries.) I'm tinkering with a prototype now and when I have a buildable project put together I'll post details on it. It uses easy-to-find CMOS 555 timer chips (TCL555) and a power MOSFET (IRF520) to drive the LEDs and it pulls VERY little current to run. ("Very little current" is a requirement for battery-powered important things like emergency lighting, flashlights, etc.)
If you want to do the keychain-pointer thing, you can power one LED directly from a 3v lithium watch battery, and it should run for about 12 hours continuously. Get a small case like Radio Slack's part number 270-288 ($ 1.99) and stick one or two LEDs, a tiny switch, and a battery or two (3v total) into it. Poof, mini light. Maybe I'll cook one of these up as well and post build directions. These might be godsends if the power grid pukes. (Not to mention having serious trade and barter potential should TSHTF.)
To run one from 12V, stick a 470-ohm 1/2-watt resistor in series with the anode, which is the longer lead. (In LEDs, one lead is usually longer and it's usually the anode end. Connect this to the + side of the power source, or to a resistor as mentioned that in turn goes to +. If you put power to it briefly and it doesn't light, reverse the leads and put power to it briefly again.) Running two can be done by connecting them in series with a 300-ohm 1/2-watt resistor. Three can be connected in series to each other and with a 100-ohm 1-watt resistor (to limit the current flowing through them) and tied to a 12V battery. More than three and I'd recommend a driver to help balance the load out. (Using a driver would also allow them to be run in parallel so that if one dies somehow it doesn't cut the flow off from others it's connected to.) I expect to be able to run 12 LEDs with the PWM driver mentioned above off a 12V 4.5 aH Yuasa gel-cell battery for about 100 hours at 50% brightness. The driver alone pulls only a few milliamps of currnet to run and varies the current per LED from a few tenths of a milliamp to their full 30 mA rating. (It can, at lower duty cycles, pump the LEDs up to 100 mA.)
Use a small solar panel to charge a gel-cell during the day that runs say 12-16 LEDS via a PWM driver board, and you'll have a theoretically infinite-lifespan light with 48-60 candlepower of tightly-focused white light. Put such a bastie in an emptied-out lantern style flashlight and you're set. You wouldn't need a reflector since the LEDs have one built-in so that part of the flashlight could be removed entirely.
Oh, a potentially important little tidbit. These are static-sensitive, so ground yourself and your work area before fiddlign with them or you'll zap them and that's not covered by the warranty. Nichia's warranty is 90 days exchange or credit only and doesn't apply to popping them from excess voltage/current or static. If you participate in this exercise and get a bad one, send it back to me and I'll resend it to Nichia and get you a replacement.
That said, if you want to get in on this, please figure out how many you can/want to get and let me know. Please send this info to my E-mail address. When I get enough responses I'll start sending totals out to each person. When the $ is collected, the order is sent. I'm after 50 myself, although if I can spring 100 I might go that route. If we can get a thousand that'll be the best on a per-unit basis. If you only want ten or want 50 or more, matters not, as long as as many people send me their quantity as possible so I can get the totals put together. Let's aim for a goal of being ready to collect the money by March 15. Therefore let's also aim for getting all orders from interested parties in before then.
OddOne, who's pretty good at this sort of thing... fortunately...
-- OddOne (email@example.com), March 04, 1999
I recently purchased from Hosfelt (1) 25-353 white LED. Would you know if this is their stock number for the LED you will be ordering? In a black room this LED is Many times dimmer than a small candle. With the candle burning the LED will not cast a light spot on the wall from five feet away. I am hoping that there is a better LED for I could use at least fifty. But if this is the best there is than I will opt for more batteries and solar cells. Thanks for your time.
-- Dimbulb (Canfirstname.lastname@example.org), March 04, 1999.
I don't know what model they are selling exactly, but if it's not a T- 1 3/4 case (5mm wide) clear LED with a frightfully narrow beam angle it's not the same one. The one I planned to get is the one best suited to lighting applications as it has the most brightness in the smallest area.
If you could get the manufacturer's part number on the LED you bought, I can check it against Nichia's specs to see which one it is, assuming it came from Nichia.
-- OddOne (email@example.com), March 04, 1999.
Okay, here's the scoop as of 9:15 PM Central time on Thursday (3/4)...
So far we've got a total of 460 LEDs from 9 people, and one additional person interested but didn't give me a # desired yet.
If we get into the 600-700-800 neighborhood I'll ask the Nichia folks politely if they'll sell us the goods at the thousand-piece price, which will save us all 60 cents a pop.
OddOne, who'll keep everyone informed with occasional brief posts if nobody objects...
-- OddOne (firstname.lastname@example.org), March 04, 1999.