Battery Powered Altoids LED Lamp
Regulating voltage.
This is a cheap 5V regulator from Radio Shack. The LEDs are designed to be driven at a maximum of 4.5V so we will need a resistor to drop the voltage. I’m too lazy to remember and apply ohm’s law here, so I used an LED resistor calculator. To drop 5V down to 4.5V I’ll need a 56 ohm resistor. All the sources I’ve checked recommend putting a resistor in series with each LED. For asthetic and weight reasons I don’t want 4 resistors on the head so I’m going to go with a single resistor and hope the 4 LEDs have a similar enough resistance.
For the next project I’ll use a variable regulator and add a pot to the case for brightness control. I suspect the LEDs could be driven at 5V for some time, but it would certainly reduce their lifetime.
Here’s everything wrapped in heat shrink and tucked into the case. I didn’t have a 56 ohm resistor so I had to settle with a 1/4 watt 100 ohm resistor I found in my junk bin. The resistor is attached to the right lead of the regulator and covered in heat shrink. I may remove the tubing if it gets too hot. This should drop the voltage down to 3.3V and doesn’t appear to affect brightness much if any. The calculator says this array should draw 80 mA, but my meter measured just 43 mA. Not sure why the difference, but it’s producing light and not overheating so I won’t complain.
March 28th, 2005 at 4:54 am
How about a Torchlite mate.
March 28th, 2005 at 6:04 am
Hey I was reading up on your altoid lamp, and I had a thought about using a reflector:
LEDs have built-in lenses on them, and thus are tightly focused. You may wanna put the reflector facing down and the LEDs facing upward into the reflector so it spreads the light around.
kinda like:
____________
/ \ – Reflector
/ Ω – LED \
(obviously not to scale, and looking down the row of LEDs)
March 28th, 2005 at 6:05 am
Oh and I got another idea: you could use the flash reflector/lens from a disposible camera to divert the light. K, I’m done.
March 28th, 2005 at 9:04 am
How about you use the lid from another altoids tin to fashion the reflector? Then, point the LEDS up (like Jason said) towards the underside of the reflector.
Great project, by the way.
March 28th, 2005 at 9:59 am
I’ve started looking at every shiny surface as a potential reflector. Maybe a CD heated and bent over a form. I like the altoids reflector idea too. I have a surplus of cut up or mangled tins in my junk bin.
I’ve started working on plans for V2. The wishlist of features include a reflector, USB and Firewire ports for charging devices, and brighter LEDs. If anyone has good pointers to sites with better LEDs for good prices (less than $2 each), please post a comment.
March 28th, 2005 at 10:13 am
The current output of the 5V regulator might be limited, which would cause the discrepancy (43mA vs 80mA). If you used an npn BJT (2N4400 I believe) as a high current driver, you could put more current through the LEDs, increasing the brightness. Usually 50mA is about optimal brightness anyway, but possibly something to consider if part of your circuit is limiting the current across the LEDs.
March 28th, 2005 at 12:18 pm
Cool implementation. Here’s a site that I have been following, but I haven’t ordered from yet. They appear to have good prices and interesting derivative products
http://www.superbrightleds.com/
March 28th, 2005 at 1:10 pm
I might order a few of the 18000 mcd LEDs from superbright. The part number is: RL5-W18030.
4V max forward voltage at 20mA continuous. I’m thinking of using two 9V batteries in parallel for the next version. Could drive 3 LEDs in series without a regulator or resistor.
March 28th, 2005 at 2:03 pm
i’ve ordered LEDs from superbright for my car. reliable folks.
March 28th, 2005 at 2:08 pm
matty,
Thanks for the input. I’ll probably order 10 or so on payday. Look for version 2 of the lamp sometime mid April.
March 28th, 2005 at 2:58 pm
You could put the actual led in the cover of the altoids case. It would be a portable LED light. I would do it but I odnt think i have the skills….
March 29th, 2005 at 1:17 am
Umm, why not just use 3 AA’s and drop the regulator?
March 29th, 2005 at 9:33 am
A few reasons for using 4 AAs instead of 3.
1. I couldn’t find a 3 AA holder in my junk drawer.
2. 4 AAs is a bit more capacity than 3. There are some losses in the regulator, but with higher input voltage it reduces the load on the batteries, allowing them to run a little longer.
3. I don’t have a charger that will handle 3 AAs at a time. I use a rapid charger that will charge 2 or 4 batteries in about an hour. The batteries will last longer if they are all charged and discharged at the same rate.
I had considered building in a charger for the batteries, and the space saved by dropping a battery could easily accomodate a trickle charger. All these are things I’m thinking of for version 2.
March 29th, 2005 at 12:55 pm
Pop (or soda, whatever…) cans cut in half make pretty good reflectors, IMHO. I use them with CFL’s all the time.
April 3rd, 2005 at 8:27 pm
hey anton, I’d like to build one of these. Should I wait for your v2? When do you think that will happen?
April 3rd, 2005 at 9:16 pm
I was hoping to get V2 done by mid April. Right now it doesn’t appear I’ll have all the parts in time.
I’m waiting on some samples from maxim-ic. It’s been a while since I ordered samples, but they used to turn them around in a week. I was hoping to put a charging circuit in as well, but that may have to wait.
I’m also looking for some brighter LEDs, and have a few places in mind, but they will require shipping from Hong Kong to get decent prices. I’m checking eBay and a few other places, but not finding anything local. (US)
I haven’t completely settled on what V2 will entail, I’m still debating if I want a USB port to charge my phone or ipod, or if that’s too much hassle for what it’s worth. For now I think V2 will be a more efficient version of the first lamp using a single 3.3V regulator to drive the LEDs.
I’ve also been wanting to try my hand at surface mount components and may try to build a fancier circuit for version 3 with all the features I can cram into the case.
April 5th, 2005 at 10:50 am
I’ll try to build v1 just to get some experience then…
April 11th, 2005 at 12:20 am
Hi. I found this blog entry in a Google result. Nice light.
Last summer, I put twenty-five 3mm 6000mcd white LEDs into an Altoids tin. I used a 9V battery and a high wattage, wirewound resistor. Here are some pics:
http://img49.exs.cx/img49/8302/altOutside.jpg
http://img49.exs.cx/img49/4329/altSwitch.jpg
http://img49.exs.cx/img49/1921/altInside.jpg
Get your LEDs from Hong Kong on Ebay. The money you save on the lights will make up for time it takes to ship – though it really doesn’t take long anyway. I’ve placed about eight different orders from four different Hong Kong LED manufacturers on Ebay and the shipping time has been between five and ten days every time – usually 6-7 days. (I’m near the Gulf Coast in the U.S.)
April 13th, 2005 at 3:33 pm
I’ve been using American Science and Surplus myself for leds.
March 8th, 2006 at 10:12 pm
i’m wondering the same thing johan is wondering…
March 8th, 2006 at 10:50 pm
I answered Johan in the next comment:
I don’t have a charger than can handle an odd number of batteries, I had room for the 4th battery, and the extra battery gives a little more time between charges.
April 25th, 2006 at 5:24 pm
Try this LINK for brighter LEDs:
http://stores.ebay.de/RealStyles
September 15th, 2006 at 12:53 am
Realy? That’s 46160 crazy!!
September 27th, 2006 at 10:17 pm
One Luxeon LED Have 8-10 time more output of your 4 LED combined, and cost about 5$ each + shipping. You can Also purchase a Luxeon Driver CHIP for 90 cent.
September 27th, 2006 at 11:42 pm
Mast3rbug,
There have been a lot of advances in both LEDs and their prices in the year and a half since I wrote this article. At the time they were new on the market and quite a bit more than $5, I think closer to $15-20.
I’m tempted to buy a few of them now though just to see how bright they are.
December 24th, 2009 at 12:56 pm
Hi, what anti spam tool do you use? Is it working for you or..? I would really appreciate it if you could answer this question! Regards!