Luxeon Star Two 'D' cell Flashlight Mod

ElektroLumens

Flashlight Enthusiast
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Jan 5, 2001
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Location
Cottage Grove, Oregon, USA
Luxeon Star Two \'D\' cell Flashlight Mod

Hello everyone,
I have been trying to find a way to mount a Luxeon Star in a 'D' cell flashlight for some time. I would like to use 'D' cells because of battery life considerations. Size is not important. I finally found a flashlight that works, a Rayovac Industrial 3 'D' cell flashlight.
I designed and built a DC/DC step up power regulator using the Linear Technology LT1302 chip. The board is 1" X 2". This is a variable voltage step up, with 85% efficency. I put the board in a plastic film container, and it is used in place of one of the batteries. The 2 'D' cells follow behind it. I set the voltage to 3.2 volts. The shutdown of this circuitry is kind of high, at 1.8 volts, but is acceptable to me. The 3.2 volts is maintained until the battery voltage drops to 1.9, and then quickly dims and goes out at about 1.7 volts.
The heat sink is 2 aluminum plates, about 1 7/8 diameter, separated with a copper plate. The aluminum plates have been cut to have fins, for heat dissipation. They seem to do the job, although I might add one more plate.
The Luxeon Stare is mounted to the heat sink, and two small bolts mount this assembly to the head of the flashlight bulb housing, making a very firm conection. The clear plastic cover is then screwed on.
I just finished assembling this flashlight last night. Works great! I am not sure how long the batteries will last. Any input will be appreciated here. I have heard that a 'D' alkaline has 14 amp hours. Is this true? At 85% efficiency, and bearing in mind the cut off is at 1.8 volts, any idea calculation wise how long the batteries will last?

Any input or comments on my design, or improvement ideas are welcome.

Is there plans to continue to produce the Luxeon Star with the optics ? Or is only the versions without the optics going to be available in the future. Will I need to design the light with this in mind? I haven't heard anything concerning this.
I have also reserved a Arc LS, and am awaiting it's availability. I couldn't wait, and decided to make my own. I am not an electrical engineer, but a computer programmer. I had to figure out the schematics of the power supplies in order to build my power supply.

Wayne
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

Wayne,
Have you seen this webpost: http://az123.com/LED/3DLSconv/
Your light reminds me, but yours is better on account of the nice regulator inside. As far as runtime is concerned, heavens it must be a hundred hours. The one in the webpage went for more than two weeks! Although your light will not go that long on account of only two cells, it will be more useful as the hours gets up a bit. It sounds like a great light for any kind of domestic or short range use. I think you'll find the new arc LS is a serious competitor; but how about this: can you clobber a burglar with an LS? I didn't think so!
rolleyes.gif
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

Originally posted by lightuser:
[QB]Wayne,
Have you seen this webpost: http://az123.com/LED/3DLSconv/

Lightuser,
No, I didn't see that website before. I just checked it out. It is really interesting. Boy, that person did a fantastic job of describing his modification. I haven't the time or the know how to do that. In many ways I did similar things, like the wires being soldered in similar places. The heat sink I made is way better. I used 1/4 inch thick aluminum metal, and cut 2 discs, about 1 7/8 in diameter, and I cut a bunch of grooves to make heat dissipating fins. I also did away with the reflector completely, as it is not needed at all. I brought 2 small bolts up from inside, and 2 wholes were drilled in the heat sink plates, which came through and allowed me to bolt the heat sink and luxeon to the flashlight housing. The cover can be removed and the light still works.
Of course, the resistor wastes power, but so does the regulator. It wastes 15% on regulation, so that has to be figured in. Also, with this particular chip, the cut out is too high. I have another chip, the MAX756, which has a cutout of .8 volts, which would give a much longer use of the batteries, but the LT1302 can give more power, and it is also adjustable, which the MAX 756 cannot. I am trying to get ahold of the MAX757 chip, and that is adjustable and probably a very good choice.

It is amazing how long the light this other person modified lasted. I need to add one more heat sink plate to help cool better, and I am trying to avoid drilling holes for ventilation, if I can.

I am planning on selling some of these power regulators, if there is an interest. Maybe $20 or so? Not sure what to charge, or if there is an interest, though.

Well, as for hitting someone with it, it still doesn't have the mass for that, although it is better than the ARC LS will be.

I have a 4 'D' cell Mag lite, with 20 LED's in it. I run it at 6 volts. No problems so far! Now, there's a dual purpose light. It will blind a person, and then before they know what's happening, it is a great club! Never had to use it for a club yet, thankfully.

I would modify a Mag lite for the Lux, but the cost's would be too high.

Thanks for the comments and the web page tip.
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

Thanks for the comments on my conversion instructions-

I gotta get my whole LED light site written, "coded" and posted- Just haven't been able to get it done...

3 cell Maglights make a wonderful LS conversion- NO overheating problems at all with the conversion unit I have developed.

MagLSBulb.jpg


I've played around with regulators, step-ups etc, and have decided that for anything bigger than a pocket flashlight, they are a waste of money unless compactness and weight are really critical, and need for a a "constant" light level output is more important than longevity... (Just my humble opinion, and I'm in the minority here on that)
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

Silviron nice to see you're there. That was one of the earliest LS conversions. I was thinking about doing a multi LS original-body light. I wondered whether they could be mounted in arrays or not. As far as I know no one has done that yet in a flashlight. Lot of heat to dissipate, and some aiming problems too. Could be done tho. I see Lumileds is offering some ring-shaped LS arrays now.
rolleyes.gif
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

Originally posted by Silviron:
[QB]Thanks for the comments on my conversion instructions-

Silviron,

That is a really nice looking conversion with the Mag lite there! I see the three plates. What are you separating the plates with? copper?

Real nice how the unit apparently just plugs in. Real nice.

I may do a coversion like that one. I didn't use a Mag because of their high cost. But as you mentioned, with the heat dissipation qualities, it may very well be the best way to go.

I like the idea of a regulator, because of the steady consistent light, even as the batteries drain. With resistors, as the batteries drain, the light will wane.

As regards battery use efficiency, which is more efficient, resistors or a regulator which will suck the energy out of the batteries down to .8 volts? With 2 batteries as the source, that would be .4 volts each battery? With resistors, once the batteries (3) are down to about 3.5 or so, the light will begin to dim, and when they are down to less 2.5, I think the Luxeon will be quite dim, but with the regulator, the light would still be just as bright as when the batteries were fresh. ?? Just some thoughts on the subject. I can't say I know for sure.

By the way, the power supply takes the place of one of the 'D' cell batteries. This is good if you consider that you are getting the power of 3 batteries for the price of 2. It is bad because there is less available amp hours from the battery source. Trade offs?

I use the flashlight mainly for long walks in the night. So, that is why I like the larger, longer lasting qualities of the 'D' cells. Flashlight size is not very important to me, personally.

How do you include pictures in your posts? If I could do that, I would take a few of my conversion and include them.
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

For applications like cave trips or bike rides, where you know you are going to need strong light for N hours, a regulator circuit is generally more desirable.

As for comparing the efficiency of a simple resistor circuit to that of a regulator, it's hard, because you're comparing apples to oranges---steady bright light to steadily dimming light.

You already claim the regulator efficiency to be 85%.

For the resistor circuit, suppose you use 3 fresh alkaline D cells (4.5 volts) and you use a resistor to lower the voltage to 3.4 volts at 350mA. You would need a 3.1-ohm resistor to do this.

Input power is 4.5 volts times 0.35 amps, or 1.575 watts. Output power is 3.4 volts times 0.35 amps, or 1.19 watts.

Efficiency is therefore 1.19/1.575, or 76%, until the batteries start to fade.

But as the battery voltage falls, so does the current, so efficiency actually rises in the resistor circuit, eventually surpassing 85%---though the usefulness of the output at that point is highly questionable.

To include images in posts, first put the picture on the web somewhere, then reference its URL using the IMAGE button which appears below when you are creating or editing a post.
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

Originally posted by Duggg:
[QB]For applications like cave trips or bike rides, where you know you are going to need strong light for N hours, a regulator circuit is generally more desirable.Helllo Duggg,

You're right, it is like comparing apples and oranges. It all depends on what kind of light a person is looking for. If a steadily dimming light is acceptable, than I suppose resistors is okay. Personally I like to think my light is always going to be at it's maximum brightness. It's also nice to have the option of using less batteries, like one battery to power the light, as opposed to 3. I like this idea a lot.

The claimed efficiency of the circuitry is 85%, but this also varies with the input/output ratio. As this ratio increases, the efficiency decreases. Actually, if converting 3 volts to 5 volts, for example, the efficiency is up around 87%. Inductor selection and capacitor selection can also change the efficiency as well.

I have other circuit designs, like a switching buck regulator, which may have efficiency as high as 95%. This would be out most step ups and resistor combinations, I am pretty sure. I am making one of these now, with the LM2595 chip from National Semiconductor.

I will just have to do a test and see how long the light will last continuously. Before I do, I will be placing a thermal fuse on the Lux/heat sink union spot. If the temperature gets too hot, the light will just blow the fuse, not the expensive Lux. I am purchasing some 98 centigrade thermal fuses for this purpose. I also have some LM35 temperature sensing chips, which I will also put on the Lux/heat sink union, so I can monitor the actual temperature of the light with my DVM. I already burned up one Lux in testing, and I don't want to do that again.

Thanks for the tip on adding photos to the posts. Unfortunately, I do not have my own web page at this time to post photos. In the future, I plan to set up a web page, and post my ideas there.

I am looking into getting some Luxeon emitters. They should be interesting. There might be more possibilities, not having the one inch back plate to deal with. (Do I smell burning circuitry?) Well, at least they are about $3.00 cheaper. Thermal fuses blowing everywhere?

Wish I had the ARC LS already! As far as I know, I have a first production numbered light coming.

By the way, the Rayovac Industrial flashlight is also a great flashlight for NICHIA LED conversion. I run 4.5 volts into 12 LED's. Works really nice. The round LED PCB board I made bolts right to the housing. Remove the reflector, put the cover on, and it is a really nice light. The Luxeon Star at 3.3 volts, and the 12 LED's at 4.5 volts appear to my eyes about the same brightness. The amperage draw should be about the same, right? Man, I really need to buy a DVM with amperage readings!
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

I think Pongo is one of the low cost picture hosting services (www.pongo.com) a few cents per picture per month. I had a couple on there at one point for some eBay sales. Make sure they are not eBay only.
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by lightuser:
I think Pongo is one of the low cost picture hosting services (www.pongo.com) a few cents per picture per month. I had a couple on there at one point for some eBay sales. Make sure they are not eBay only.<HR></BLOCKQUOTE>

I'll provide picture hosting FOR CANDLEPOWER FORUMS photo hosting and small LED light related websites AT NO CHARGE, and they can be linked to from anywhere, unlike most of the free or inexpensive hosts.

Email me if you want some.

[email protected]
 
Re: Luxeon Star Two \'D\' cell Flashlight Mod

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Wayne Johnson:
That is a really nice looking conversion with the Mag lite there! I see the three plates. What are you separating the plates with? copper?

Real nice how the unit apparently just plugs in. Real nice.
<HR></BLOCKQUOTE>

Thanks!

Nah, it is a slightly modified one-piece heatsink from: ALL ELECTRONICS

The real trick was getting the screw-on lamp holders from Mag-light to make this a secure, easily reversible conversion.
 
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