Well it just croaked and I bought an adapter to get a conventional threaded socket.
(Funny, the gov't assholes... the fixture came with an 120W equivalent CCFL... try and buy one now... you can find them, but price and shipping is exorbitant. And the local Lowe's and Home Depot have only lower wattages.)
So I'm pondering... how do I build a super efficient LED lamp with ~2000 lumens? (I have lots of volume, so a big inductor is easy to fit in... I just need low dissipation.)
Suggestions? Pointers? ...Jim Thompson
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| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
LEDs are maybe 10% efficient, so the important feature isn't the inductor size, but the heatsink behind the LED die. I have a so-called 10W LED that runs very brightly at 3W, that enjoys a surplus Pentium heatsink, fanless... For 2000 lumens, Cree MHD-E chips (two of 'em) would do, and take 18V, 800 mA. Expect to dissipate 13W as heat, and you'll want to keep junction temperature below 85C.
One approach is to buy incandescents, which are still available on the grey market. A proper 100W bulb is around 1690 lumens. (I still have around 200 of them from before 2012, but 1000bulbs.com is your friend.)
Cheers
Phil Hobbs
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Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Was at Costco today. They had a 2000 lm work light for $30. Didn't look carefully, so don't know whether it's easy to disassemble reassemble in your application.
Back when 40W equivalent leds were $1 and 60W were > $10, I used to use a dual socket converter to use two 40W.
I have some pipes that I keep from freezing by shoving a 100 watt light bulb in next to them. I'm pretty sure the CFLs and LEDs won't save me any money in this application. Too bad I can't buy 100 watt incandescent bulbs anymore.
I made a small one a couple years ago, using Cree XPEBWT-01-0000-00CC2 "1 Watt" LEDs. I did a massive search at Digi-Key back then and determined this one had the best Lumens/Watt at a reasonable price. My first one used an LM3404HV lighting current regulator chip and a transformer-rectifier power supply. I had 10 of the Cree LEDs in series, running at 300 mA. Did a GREAT job of lighting up a dark laundry-pantry area in our house.
So, then I built a 20 LED replacement for dual 48" fluorescent fixtures. One set of 20 of these LEDs fully replaces a pair of 48" fluorescents. See
formatting link
I went with a commercial power supply for these. It is rather expensive, but small, very efficient, and I don't have to fiddle with it.
The heat sink is just PC board material, about 4 square inches per LED.
So, I'm pretty sure you could make any lamp you want. Do you really NEED
2000 lm? These replacements for DUAL 40 W fluorescents run about 2000 lm (on 21 W 120 V AC input power), and you'd better NOT look at them without a diffuser over the LEDs! You will be seeing spots for some time.
As for efficiency, these LEDs are 104 lm/W, which still seems to be nearly as good as it gets. Higher efficiency can be had at massively higher prices.
Neeeerp! Most of the house is already done with GE LED's, 10W=60W equivalent. ...Jim Thompson
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| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
If you are referring to LEDs with Imax=3 A i.e. "10 W", I very much doubt that they would produce more than 100 lm/W at Imax. Anyway, running those at Imax and the effective lifetime may drop to less than
10000 hours. The heat removal at Imax is also very hard.
However, running those at 1 A, you will get past 100 lm/W even with usable colour rendering. The effective lifetime can be quite high. To get 2000 lm, you would need six of those "10 W" LEDs in series driven from a 1 A constant current source. The heat removal is not so big problem.
I built a 1 to 5000 lumen hiking/bicycling lamp using an 3 x 8 array of Luxeon LEDs with front-silvered parabolic reflectors. The power supply is a LM22679 switcher. The sealed brightness control pot has a calibrated voltage divider on the low end, a calibrated current sensor on the high end, and the brush going to the regulator feedback. The LEDs are mounted on 1 oz double sided copper 0.01 inch thick PCB, and that's glued to a custom aluminum chassis. Power is an external LiPo battery pack. A few extra parts provide protection against overheating and a broken pot. Some of the series LEDs are bypassed with a resistor so that the flashlight can be seen glowing in total darkness while the power pot is turned down.
It's a tiny flashlight so it will burn your hand running at 60 Watts continuously. That power is more for relocating a trail while night hiking. Normal power is around 1 Watt.
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I will not see posts from astraweb, theremailer, dizum, or google
because they host Usenet flooders.
You could do worse than the LED-light example on page 835 of AoE III. I prefer purchasing my high-intensity lamps, but Paul made his own. A fan takes care of the obligatory heat.
BTW, Jim, AoE is largely free from errors now, 5th printing on, and Amazon just dramatically lowered their price. Time to get your copy, and start enjoying all the cool stuff we spent 10 years putting into chapters 5 through 15.
Does Amazon have the 5th Printing? ...Jim Thompson
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| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Easy to do better. Reptile heater "bulbs" will put out all the heat and none of the light, and are much less likely to burn out and leave you heatless - screw right into a lamp socket so you don't even need to find a plug adapter. I've used 90 and 150 watt sizes (for chicks, which are basically dinosaurs, so they are closer to reptiles than one might think.) Looks like sleazebay will sell you a 100 watt "ceramic heat emitter" for $4.48 shipped.
A "goldenrod" heater (as seen in pianos and/or closets in some necks of the woods) will also work. Purported to be a dehumidifier, but it's just a heater. Probably too rich for your blood, though.
Plenty of low-wattage heat options that are not nearly as fragile as a bulb, if what you need is the heat.
The one place I really like incandescent bulbs is as a self-indicating high-power resistor. And there are still plenty of available bulbs to fill that role.
As for the original question here, I have a bunch of inconveniently modern LEDs. It's so tiny - but you have to attach it to a huge heat sink - but we make that annoying by making it wicked tiny, and possibly (documention is vague on this point - could go either way) not even providing a polarity clue on the device (keep track of how it comes out of the tape, won't you?) on hand with the intent of making a lamp or several, but in actual practice the convenience of $5-$15 bulbs and fixtures has put a cramp in the roundness of that tuit.
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Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
Amazon has been shipping the 5th printing for quite a while. Some sellers are importing the 6th printing from the U.K., because the list price is lower there. But the 6th printing is identical to the 5th. Both have the first 75 errors and hundreds of minor typos fixed.
The Kindle edition is the 7th printing, and includes a final 15 errors fixed. We haven't learned of any additional errors in the last 3 months, so they must be virtually gone now.
The complete list of fixes is on our website,
formatting link
Sort it as you wish and saved a file for printing.
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| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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