High-efficiency LED reading lamp

Have you ever wanted to read at night but are frustrated by wasting energy with those 50 or 60 watt lamp light bulbs. If you are like me, you bought a few dozen CFL's. But when you realized that the light given off by those bulbs is too harsh and unnatural (even the so-called 'Sunlight Simulator' bulbs), you decided they had to go. So you decided to try a clip on LED book light. But like me, you were probably frustrated with the thin, dim glow and having to move it every time you turned a page. For years I put up with this. Until I found a website called Instructables. Instructables gave me the inspiration to build my own LED lamp. Sure, you could buy an LED bulb. But the el-cheapo bulbs flicker and the ones that don't are too expensive (they start at 30 US dollars). I set out to build one for less than 10 dollars. Sadly, thanks to expensive shipping rates (and I live in the U.S. too!), it ended up being a little more. But in the end, it was worth it. The entire array, including all 8 (yes, 8) LEDs and 4 resistors draws a grand total of 1 watt per hour! That's a savings of 59 watts over the incandescent lamps I used to use and 29 watts over the CFL that replaced the incandescent bulb! And the light is bright but not too bright and is easy on the eyes. So, on to how I built it.

Step 1: Materials

From allelectronics.com (www.allelectronics.com)

White Ultra Bright 5mm LEDs x 8 (I went ahead and ordered 100 for other projects around the house since they were so cheap) Category # LED-121

270 ohm, 1/4 watt resistor (I ordered 1,000 to use when I build the LED lights for my house to run off of; no really I ordered that many!) Category # 291-270

From Radioshack

10 packs of 75 foot long rolls of 22 gauge solid core wire (no really, I did buy that much).

On to tools.

Note: you can buy however many LEDs, resistors, and wire you want. I bought so much because it was on sale for really cheap. In the end, I'll save money.

Comments

[wildwheelie]

Try Parts-express dot com. Their price is so much better than what you quoted. They also include the resistor with the LEDs.

Nice job, by the way.

[vipulprajapati84]

Hello Friends, I want to know information about Industrial LED lamp means street light or more illuminated LED lamp. if any body have this info then please share with me my personal email id is [e-mail]

[thetech101]

First: don't post your email address on a public place like this. Spambots can grab it and flood your inbox. Second: LEDs are used industrially. Im my area, they've switched the traffic lights to LED bulbs. However, they are not quite bright enough for street lights. The LEDs would need to be diffused and diffusing them changes the brightness. Some companies do make LEDs bright enough for street lights, but they are very expensive (>100 dollars per bulb). And they would still need several bulbs to make the light bright enough. To shorten the above, LEDs are not economical yet because of price. But in the future, as the price comes down, they will likely be used because of the energy savings they provide.

[crampedyogapositions]

isn't the light to dirrect from a LED? shouldn't you diffuse it?

[thetech101]

It does need a diffuser. The LEDs reside just behind the original bulb holder so even if you look directly at the lamp, it's not too bright. The first picture in step 8 is about as bright as it gets. The main problem is the uneven light patter it spreads on the wall. Look at the second picture in step 8 and you'll see what I mean.

[salobyte]

you could always find an ac adapter from something small such as a cellphone charger, radio, battery charger (ironic stuff)... just a note.. make sure you take a small lesson on voltage (if newbie) so you don't burn your electronics...

[thetech101]

Trust me. Experience is the best teacher. I know first-hand that it's the truth.

[thetech101]

Oh, and I do plan on using a small 12V 500mA AC adapter for the small stuff like this lamp. A simple 12V 500mA adapter would power 40 or so of the LEDs in my configuration.

[thekanester]

Using resistors is quite a lossy process. Did you consider using some form of regulation and a single, efficient 1w LED at all? I love the way you crammed it all into a standard angle-poise form factor. It's really practical!

[thetech101]

I did but resistors were the cheapest. Each resistor was only $.05 US dollars. Plus the only 1 watt LEDs I could find were 12+ US dollars.

[thetech101]

In the end, it would have cost about the same. Do you know anywhere I might could get some cheap 1 watt LEDs?

[thekanester]

Hi tech101 Thanks for your reply and the info. I've been inspired by this instructable and want to try similar! You can get a bunch of amazing and cheap (free postage worldwide) LED stuff at these sites: www.dealextreme.com www.kaidomain,com Takes about 2 weeks for delivery. You can get 1w LEDs from around $2ish and they also sell constant current sources which operate in various voltages from 3.7.-4.2 DC (for lithium batteries), 12-16 volts DC and even from 120-240 vac. They're really jolly cheap. Both CREE and SSC LEDs are very good, and efficient and quite cheap at those sites. Check out the CREE P7 LEDs which are quad core LEDs, running at 3.7v and 2,8 amps. They're putting out in the region of 500-700 lumens! Anyway - great instructable makes me want to do something similar, thanks!

[thetech101]

Your welcome. The lamp was a lot of fun to make and well worth it. Have you read the last step (I just added another one)? I'll be updating it soon with payback time for the project. I didn't say this above, but the light is concentrated enough that, if you looked directly into the diodes, is just as bright. Lumen-wise, they put out less. Those quad core LEDs sound a bit to bright for a reading lamp. But I do plan on making outdoor spotlights and might use those. But that's a few months off.

[chaosrob]

To diffuse, I 'file' the LEDs down a bit. That leaves a nice, rough surface that gives good diffusion. I use like a 220 or higher 'grit' sandpaper, or a emoryboard (nail-file).

[thetech101]

I never thought of that. Thanks for the idea.

[kelseymh]

So what, exactly are you going to do with the other 9,992 resistors? Build an infinite grid and kill physicists with it?

[thetech101]

No. I plan on converting my parents house to all LED lighting and when I get my own built, I'll do the same. I couldn't help it. I like to build stuff and eventually all of the resistors will have a home somewhere where they are useful.

[Lithium Rain]

:'D xkcd FTW!

[thetech101]

?? I'm sorry, I never learned how to read chatspeak.

[ReCreate]

Finally,Someone who understands me!