What is Digg?43 Comments
- bu11et, on 10/12/2007, -0/+8I'll digg but it could be better: 1) For the love of a higher power, don't solder wires to batteries. Very bad idea. It's not hard to hack some battery contacts. 2) Instead of putting a resistor in series with every LED, simply wire the LEDs in parallel and put a single resistor in series with the LED bank and the batteries. In his first example with 3 batteries (4.5V) and 9 LEDs @ 30ma each, it would take a single resistor of about 4 ohms.
Discount stores sells cheap plastic flashlights that could probably be easily modded with LEDs. They already have the battery case, battery contacts, and switch. Some of them even come with batteries. - bugmeno19135, on 10/12/2007, -0/+6pdf's aren't bad. Just as long as you're using foxit and not adobe. Link for foxit for those who don't know about it. http://www.foxitsoftware.com/pdf/rd_intro.php It's free and way better than adobe
- fuelishgreg, on 10/12/2007, -0/+2This thread makes me ask, would it be feasible to light the home with LED's?
This would save power and hopefully the LED's would last longer than incandescent or even flourescent lights. By adding rechargeable batteries, the home lighting system would still work if "the grid" fails for a day or two.In the Andes mountains in S.A. people are setting up solar cells with LED's to light essential parts of the household like the kitchen.
For a commercial comparison, check http://www.ccrane.com/lights/led-light-bulbs/index.aspx
In keeping with the DIY slant of the article here is a more appropriate link: http://www.scienceproject.com/projects/intro/senior/SE012.asp - Rayfound, on 10/12/2007, -0/+2This seems like it would be awesome to do with an old 3.6V battery from a cell-phone, Li-Ion rechargable flashlight... yeah baby.
- arizonagroove, on 10/12/2007, -0/+2Where's the reflective part to focus the beam?
Homemade and looks it. - emo1313, on 10/12/2007, -0/+2agreed, a 6$ save just doesnt seem worth it unless its just a little fun project you want to work on -vs- wanting something truely functional
- KidVicious, on 10/12/2007, -0/+1Wish it showed the final product.
- Mesach, on 10/12/2007, -0/+1How can it run much longer than the one posted...
its the exact same one. - inactive, on 10/12/2007, -1/+2"2) Instead of putting a resistor in series with every LED, simply wire the LEDs in parallel and put a single resistor in series with the LED bank and the batteries."
While it doesn't usually make a large difference, not all of the LEDs will perform exactly the same. The one with the least resistance will burn the brightest. Adding a resistor in series with each LED will level out the brightness some and increase the life of that LED..
I've tried some tests both ways and it probably doesn't matter much unless you're pushing the LEDs near their limits to.
If you're interested in saving some resistors, you can arrange the LEDs in a series/parallel arrangement or get some high output LEDs that can handle the 4.5V with no resistor. - oldcyborg, on 10/12/2007, -0/+1I am usually easily entertained, but I would rather spend my time finding a good deal on same. Soldering batteries was the last straw....\
Cyborg
Ok for entertainment - abbtech, on 10/12/2007, -0/+1LEDs are much more efficient then incandescent bulbs but not as efficient as florescent bulbs. Also most LEDs through most of their light in one direction although there are some new 360 degree LEDs that act more like a standard bulb. It wouldn't be cost effective to use them for everyday lighting in our homes yet though.
http://alan-parekh.vstore.ca/index.php/cPath/4 - tavisjohn, on 10/12/2007, -0/+1OK the PDF file here has a total $ of 23.00... If the commertially available ones are $29.00 then I may make one for fun. However if I want one to use often, I'll spend the extra $6.00 on a commertially produced one.
- daguuy, on 10/12/2007, -0/+1whao i actually beat somebody to something. check out my duct tape PVC LED light:
http://img65.imageshack.us/img65/6062/ledlight12sd.jpg
http://img162.imageshack.us/img162/8981/ledlight39ts.jpg
http://img220.imageshack.us/img220/2585/ledlight28va.jpg
yeah i'm a pretty sucky photographer.
->daguuys.tk - imdigginthis, on 10/12/2007, -0/+1The entertainment value is pretty good. Digg!
- mikedpirone, on 10/12/2007, -0/+1I got one of those never have to replace the battery led flashlights that you have to shake for it to have power. It actually stays lit for a good 2 hours before you need to shake it again and it only cost me 4 bucks at a flea market.
- Roger, on 10/12/2007, -0/+1All those resistors are just wasting power. Interesting idea though, too bad LED flashlights are so cheap.
- sjalt, on 10/12/2007, -0/+1led only project light in one direction, putting a reflector behind the light does nothing, however, a fish eye lens would help focus the light towards a smaller point.
- dielawn, on 10/12/2007, -2/+2ZOMG LIGHTSBAER
- NiLeS, on 10/12/2007, -0/+0"For the love of a higher power, don't solder wires to batteries. Very bad idea. It's not hard to hack some battery contacts."
True Dat. Besides all of the potential leakage, what happens when the battery dies? - bikeham, on 10/12/2007, -0/+0Not sure about bu11et's idea of eliminating the load sharing resistors and using just one. The internal resistnance of the LEDs vary a fair bit and you may find one LED eats all the juice whilst the others languish?
- KeithRaymond, on 06/01/2009, -0/+0Thanks for the information!
- Jaan, on 10/12/2007, -0/+0They make L.E.D. flashlights dirt cheap in China these days ... there's always a few guys at the flea market with them (especially the M.I.T. swap fest in Boston) and even my local drug store has 20 L.E.D. flashlights for $10. Not worth it.
- eddieo, on 10/12/2007, -0/+0Lost me at V=IR.
- forgetfulca, on 10/12/2007, -0/+0diy = must be dugg. Although with this crowd it seems like the answer will mostly be "what? get off the couch?!?"
- servicingyou, on 12/24/2008, -0/+0Thanks for sharing..
http://expertplumbingutah.com/ - solarpowered, on 10/12/2007, -0/+0Hmmm. After going to all that trouble, do you suppose the author might feel a bit sheepish about wasting all that power in the resistors?
A simple circuit that pulsed the voltage to the LEDs would do two things:
1) Allow higher peak current on the LEDs than the steady state spec calls for, persistence of vision smooths it all out
2) Increase the efficiency, by a lot.
Like this:
http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=12083 - Weezel, on 10/12/2007, -0/+0looks like a pipe bomb to me....
- cphuntington97, on 10/12/2007, -0/+0And the flashlight is so beautifully finished off...
I mean, I guess it doesn't matter if you only use it in the dark... - bnubbz, on 10/12/2007, -0/+0Foxit is awesome. It goes so much faster during start up and while you're using it. I saves resources too!!
- hkorth, on 10/12/2007, -0/+0eddieo, no wonder he lost you at V=IR, because the explanation is nonsense. The resistrr is needed to limit the current through the LED and not to reduce the voltage...and no, you don't need a resistor for every single LED unless you want to buy the batteries in bulk. no digg from me.
- Roger, on 10/12/2007, -0/+0bu11et:
A single resistor wouldn't work for most LED's. LED's have an exponential I-V curve, so if just one of em a lower "ON" voltage, it could easily rob current from all the others.
Some kinda PWM circuit would be ideal. - Googled, on 10/12/2007, -2/+0thanks for the heads up on the pdf, it p155es me off when people don't mention it (i'm just to lazy to look at the status bar) :p
Although with foxit its not really a problem aby more, they load ~straight away - Mesach, on 10/12/2007, -2/+0you can use adobe if you know how it should be configured first, I tried Foxit, and it constantly crashed.
- teh_toaster, on 10/12/2007, -2/+0"She called it our 'love flashlight.' "
WTF? - drbroccoli, on 10/12/2007, -2/+0I use xpdf.
- flashmaster, on 10/12/2007, -4/+0Post as HTML if you want me to read it.
What kind of moron links to a pdf?
That format is meant to be printed, not read like a web page.
Uggggh, now go ahead and block me. - ronmexico, on 10/12/2007, -8/+0I'll just buy my next flashlight thank you.
- beelz, on 10/12/2007, -12/+1pdf.
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