WHITE LED FLASHLIGHT

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Edd
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WHITE LED FLASHLIGHT

Post by Edd » Mon Dec 08, 2003 6:42 pm

For Info Only:
If any one is planning on construction of a white LED flashlight without incorporating the pricey combination of dual 3V Lithium cells that one finds in commercial models; they just might find the information in this current article of use. No exotica I.C s involved , just common bipolar components. And the utilization of a more common and cheaper power source.<p>http://www.elecdesign.com/Files/29/5886/Figure_01.gif<p>(The second site is a forerunner circuit.)
http://www.elecdesign.com/Articles/Inde ... cleID=5886
Also:
http://www.elecdesign.com/Articles/Inde ... cleID=3892

73's de Edd
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;)<p>[ December 08, 2003: Message edited by: Edd Whatley ]</p>

josmith
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Re: WHITE LED FLASHLIGHT

Post by josmith » Tue Dec 09, 2003 4:24 pm

Commercial products are finally catching up. I just found a Dorcy brand single cell white led flashlight. It draws 60 ma at 200 kc so I assume it has some kind of voltage multiplier. It's about time for the consumer. For the manufacturer, the market for $30 three cell units is on borrowed time.

perfectbite
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Re: WHITE LED FLASHLIGHT

Post by perfectbite » Wed Dec 10, 2003 2:07 am

After a 7 hour evening blackout a few months back and after smelling the house up with kerosene fumes from a matchhead sized hole in a Coleman Lantern mantle. (I kept telling myself, the juice'll be back on any minute now) I found I needed a lamp, shaped like a lighthouse. Imagine a paper towel cardboard core fastened securely to a 1" or 3/4" pipe floor flange, with the LEDs radially projecting from the cardboard tube at the top and a piece of duct tape under the hole to keep the batteries and innards in the tube with some powdered chalk or talc dropped in the tube to stop stuff from sticking to the duct tape. That maybe, just maybe, could give enough light to read by but would illuminate a room area. If I wanted to get fancy I could take some aluminum foil and make a light reflector cone for each or all of the LEDs. Now I know how to light the LEDs. :) Thank you.

Larry Woods
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Re: WHITE LED FLASHLIGHT

Post by Larry Woods » Wed Dec 10, 2003 5:17 pm

I'm interested in lighting up a number of these LED's and was wondering how many I could put in Parallel ( correct ????) to get more light. Not concerned on longevity(assume a bigger battery) but more on circuit handling the load.<p>Thanks people

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Edd
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Re: WHITE LED FLASHLIGHT

Post by Edd » Thu Dec 11, 2003 3:43 pm

Well Larry, as far as this upverter circuit is concerned, figure on it to supply only one LED adequately on its voltage and current requirements.
Multiple LEDs in parallel typically don’t balance out too well, so figure on using an individual series current limiting resistor feeding each individual LED along with a higher power supply voltage needing to be provided..
In my case I was going to replicate a commercial flashlight that my son has that uses 5 white LEDs fed from 2 series 3 VDC lithiumyumyum cells. They are feeding each cell thru series current lim resistors with the whole cluster consuming 230 ma DC. Thus giving a mean average current to each LED of ~46 ma….so I guess they are not worried about that higher current drive level on their designs reliability.
I was merely thinking of repeating the provided circuit 5 times for feeding each LED and using a “C” or “D” cell for power, whichever I’m the happiest with for longevity.<p>73's de Edd
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Ron H
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Re: WHITE LED FLASHLIGHT

Post by Ron H » Thu Dec 11, 2003 7:40 pm

Have you guys seen LM2794/2795? Unfortunately, it only comes in a ball-grid array type package. LT1307, from Linear Technology, won't drive as much current, but it does come in an 8 pin DIP, as well as a surface mount package.
Both have efficiencies of 75-80%.

jbsteele
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Re: WHITE LED FLASHLIGHT

Post by jbsteele » Tue Dec 16, 2003 12:08 am

I found an interesting flashlight at the Goodwill for 99cents that would make a nice LED conversion. It's got 4 AA cells, in a '2x2 cluster'. The thing is made of 2 telecsoping plastic tubes. The inner one is translucent and has a conventional flashlight type of reflector/lens attached. When the two tubes are pushed fully together, the bulb sets at the focus and it works like a typical flashlight. Pull it out and the bulb shines through the translucent tube giving an area light. Of course the LEDs are more directional than bulbs, but it still works fairly well.

Gary
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Re: WHITE LED FLASHLIGHT

Post by Gary » Wed Dec 17, 2003 5:12 pm

WalMart recently had some LED flashlights for kids. Cheaper and one did "lightshow" effects too.

Tparker
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Re: WHITE LED FLASHLIGHT

Post by Tparker » Thu Dec 18, 2003 12:22 pm

Its pricy but here is a 1.2 watt plug and play Luxeon Star LED in a PR mount that will fit any flashlight that takes a PR type bulb with 1-6 cells. http://www.ledsupply.com/evflbu.html<p>[ December 18, 2003: Message edited by: Tparker ]</p>

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