Converting Minimag (2AA version)

Hi folks
It is really great how you all are sharing your knowledge and experience with others! I already learned a lot!

Even I'm a newbie in this board I started already my second thread. The reason is: I noticed that there are a lot of threats starting on a specific topic but after a few posts changed the topic. You have to get through the whole board to get the informations.

For example I've found several threads with some more or less complete informations on how to convert minimag's but none which has this as a specific topic. So it would be great to keep this single topic in such an own thread and not to change to how to convert a Maglite 3D or something else. I think converting a Minimag (this is the one with 2 AA cells and the little bulb) is a specific topic. (Sorry for such hard words from a newbie . I'll try to make it better in future!)

I made my first convertion with the Minimag a few weeks ago. It was very simple: Just replacing the bulb with a white Nichia LED and the 2 AA cells with 3 N cells. The result is also very simple that means not satisfying. Its a poor light for such a housing. An ARC AAA as a great tiny little thing is brighter. I own a few of these Minimags and like this housing. Why not making a great LED flashlight out from it?

So what I am searching for: A convertion for the Minimag either with 3 - 6 LED's using the original 2 AA cells or a bulb replacement eg. like the Versaluc PR-2 for bigger flashlights. Of course for the first solution one has to have a step up converter which fits into the head of the Minimag.

My problem is that I'm (better I was) an engineer twenty years ago but completly out of practice. So I wouldn't be able to build my own step up converter even one could find some very good informations on this (eg see here http://mikro.e-technik.uni-ulm.de/persons/lares/LED_flashlight.html#V2 ).

Today I got a great tip in another thread on how to convert bigger flashlights with the Versalux Utility Module. Is there something similar available for converting the Minimag or can someone tell me how a beginner like me (as far as I learned there are a lot more guys like me in this forum) can convert the Minimag much better than I did it?

Thanks a lot for your help!

this is a 7 led conversion thread (though it used N cells): http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=000367

I did a conversion for a 2-AA aluminum flashlight that uses 2-AA's. I wanted the AA's over N's for excellent battery life. The conversion has been running great for half a year. I used the non-alkaline heavy duty cells for the first set of batteries and they lasted a good 30+ hours of intemittent run time. You could use the same circuit to power 2-3 LEDs. I chose a flashlight with a push button switch so that I'd have a little extra room for circuitry inside the flashlight - and not disturb the reflector assembly. Here's the details:

Craftsman 2-AA conversion

Oh guys

I see you want me to be a real flashaholic which builds his own step up converter. Give me a few days to think about this.

I've also something for you guys to think about: You could become very very rich making such a conversion set and selling it. Imagine how many Minimags are spread all over the world. Of course all Minimag owners would immediatly buy your conversion set!!!

I won't force a step-up converter down your throat. In fact, I've never built one myself, yet I have more than 200 flashlights.
Does this mean I'm still not a flashaholic?

Hey Stingmon

I'm happy that you looked into the thread of such a newbie like me!

Your homepage was one of the first I visited when I got into the LED matter. It's a great site. Because of your review in the punishment zone I bought up to now already 10 ARC AAA for me and my friends (Peter Gransee, do you see what these guys are doing for you?)! Thanks for all you are doing for us!

True, Stingmon's greatness is a grace to any topic.
(In fact, I hope to benefit from his wisdom on another matter, quite soon. Must post those questions ...... )

He tends towards the helpful, he's knowledgeable, and he gets things right.
Whether you're a "new chap" or an Expert, he will discuss away, and/or advise as necessary.

Don't you agree, Doug ?

lightlover

Oh, and welcome aboard remuen !

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Don't you agree, Doug ?<HR></BLOCKQUOTE>

Ummmmmm... Which Doug? I think there's at least 4 of us here !

But if you were referring to me, I agree! Stingmon is definately a "Hoopy Frood" (in the words of Ford Prefect - HHGTTG).

(that's a "really cool guy" for those uninitiated souls out there )

Another conversion, since it appears a luxeon star led can be pretty bright with 3v (or slightly more with Li AAs), is described here: http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=000696

here's a circuit board i drew up based on the zetex ZXSC3x0 IC...this is all theoretical right now, i've never even attempted to build it...but i will after christmas and we'll see what happens...it's 14mm accross and meant to just pull the reflector and bulb out of the mag and drop this in...i don't see why it couldn't be as bright as any other 3 LED overdriven light...

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by remuen:
It was the target of this thread to gather all the information about converting Minimags. It seems that exactly this happens. So me and all other newbies (and mayby you cracks too) don't have to search through the whole board which costs a lot of time. If you have some more informations and links please place them here.

If you're suggesting someone else do all the searching and re-posting for you, that's a lot to ask, isn't it?

Does someone know how bright a Minimag is whith such a Luxeon Star? Are there somewhere pics of the beam?

Yes. Search all the threads that contain "luxeon" and I think you will find some beam photos.
<HR></BLOCKQUOTE>

As you can see, there's a lot of interest in coming up with a board that will fit inside a MiniMag and drive a Luxeon Star. Once we do, you'll be able to obtain the bare board, a board with all the parts, or even a completely soldered board where all you have to do is hook up the LS.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Duggg:
As you can see, there's a lot of interest in coming up with a board that will fit inside a MiniMag and drive a Luxeon Star. Once we do, you'll be able to obtain the bare board, a board with all the parts, or even a completely soldered board where all you have to do is hook up the LS.<HR></BLOCKQUOTE>

The longer the more I like the idea with a step-up/DC-DC-converter because one could squeeze the batteries much more and with a bright light almost until the batteries are dead. I made a test with my ARC AAA. It is astonishing how bright the light still is with a battery that made only a little glue in one of my Maglites Solitaire.

papasan i want one if you ever make it!

Great, you're providing more information than I can "swallow" at the moment, because I'm working 10, 12 or more hours a day in the last few weeks. I will try to review all your posts during christmas holydays.

It was the target of this thread to gather all the information about converting Minimags. It seems that exactly this happens. So me and all other newbies (and mayby you cracks too) don't have to search through the whole board which costs a lot of time. If you have some more informations and links please place them here.

Does someone know how bright a Minimag is whith such a Luxeon Star? Are there somewhere pics of the beam?

I also would love to convert a 2AA to a 7 led array with a dc/dc converter for max light over the life of the batteries. Now this is where I would need help. I am somewhat mechanically skilled but electronically challenged. I have taken courses in electricity and am now taking a course in basic eletronics, so I'm on the way. I(and maybe other newbies) would, like~need~politely request, any mods that have a parts list, PCB layout, schematic and maybe a photo posted. I have followed theads on mods but cannot grasp enough to do a mod myself. Anyone?

http://mikro.e-technik.uni-ulm.de/persons/lares/LED_flashlight.html#V2

The guy from Ulm posted here once. He even said he had a couple boards to give away. I was going to ask for one but I think he gave them to someone else.

Maybe if someone writes to him he'll come and visit us and help out.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by jeff1500:
This is a method for soldering small surface mount ICs. http://www.seattlerobotics.org/encoder/200006/oven_art.htm
Here's a little tiny MAX1701 IC with a schematic http://dbserv.maxim-ic.com/quick_view2.cfm?qv_pk=1830

Here's a larger MAX757 IC that's easier to make connections. http://dbserv.maxim-ic.com/quick_view2.cfm?qv_pk=1167

I'm in the process of hooking up the MAX757 just to experiment. <HR></BLOCKQUOTE>

Jeff1500, you sent me this post in another thread. Can you tell me whats the real difference between the IC's MAX1701, MAX757 IC and the Zetex ZXSC3x0 IC on which a special thread is running? Papasan is also working on a conversion with the Zetc IC (see his earlier post in this thread).

By the way: I found a conversion with LED's in a tailcap. It's not the way I want to convert my Minimag's but if someone is interested here is the link http://electriclights.tripod.com/flashlights/outtec.htm

That's a very interesting conversion module. And I too would like to have a converted AA Mag light. Here's the ideas I have:

1. What's the difference between the chips?

a) Size is a big deal. Too small and it's very difficult to hook up to. Too big and it won't fit. The MAX1701 does a lot of great things and as I recall it will take quite a bit of current flow, but it's just too small with too many connections. It has 16 pins.

b) The MAX757 is a pDIP chip, that's plastic dual inline package. This is a comfortable size to work with. It's an older chip with a lower, but I think, still respectable efficiency. It has 8 pins.

c) Here's a very nice application of a small surface mount MAX867, also with 8 pins. It's in Czech language but you can look at the photos and the schematic.

Click to see very nice Czech Light

He's only using one led and one battery, but two batteries and more leds would work too. He shows two circuits, one with transistors, and one with an IC for higher efficiency.

d) The Maxim chips seem to have a lower minimum starting voltage. Other chips I've seen people reference are LT1302, LT1073, LT1070, but I don't seem to like them as much as the Max chips.

e) Today, and it might change tommorrow, my favorite picks are MAX757 because it's big and I can work with it easily, and MAX867 for a smaller smaller surface mount one since I've seen it working.

f) I've been watching the Zetex discussion a little. I think they're trying to modify it to do more.

g) I think a few of the components on the IC schematics could be eliminated. LEDs don't need the kind of pure power that a computer does. I suspect the famous manufacturers chop the schematic significantly to save space.

2) Mag light size. I've always wondered how hard it would be to machine a short sleeve, to thread in between the end cap and the barrel to make more room for circuitry.

3) Change the rules to make things easier.

a) All this electronic stuff is just to jump up the voltage enough to make the white Nichia leds work. There are other colors that work at lower voltages that might solve the problem.

Click here for Other Color LEDs

This one for example:
8000 mcd
5mm YELLOW LED
Mfg. - TOSHIBA
Mfg. # TLYH180P(U2)
Operates on 2.1 - 2.5 VDC @ 20 mA
8000 mcd typical luminosity
T1-3/4 (5mm), colorless, transparent
Super ultra bright, lights yellow beam
Brightest 5mm LED available


Three yellow or green or blue leds might work very well in a AA Mag light and you wouldn't need complicated circuitry. And a little bit of cloudy tape makes a good beam diffuser.

b) Leds really do like a resistor in series with them. Without it, the current ramps up quickly. It wastes power and burns up the LED without giving off hardly any more light. But lots of designs get away without it. I think the leds will take quite a beating and still keep going.

c) Some leds have good beam patterns. Others do not. I wish I could see the beam patterns for the LEDs at the link above. Can anyone suggest a model number for colored leds with good beam patterns?

d) MCD, milli-candelas is a brightness measurement. It's very deceiving. A small hotspot in the beam will give a high MCD value but that doesn't mean it's proportionatly more light. I wish they'd also list lumens. That's quantity of light. I have a couple 23,000 mcd yellow leds. I don't really like them. Bad beam pattern. I suspect there are other yellow ones that are much better.

Here's my easy AA Maglight conversion for two batteries:

1) Throw away plastic reflector.
2) Solder three 1/4 watt resistors (maybe smaller) and three 5 mm colored leds onto a circuit board disk. Forget about etching the board, just use small wires.
3) Plug the board into where the bulb used to be.

jeff1500

I just looked into the thread of the Uni Ulm which is mentioned in two earlier posts. They use the DC-DC converter LT1307B and the IC MAX1759. I think both versions are not very efficient (65 - 77%) and one gets only 100mA output current.

A few weeks ago I made a simple convertion for my son in which I used one white Nichia LED (white one) with a resistor. It sucks about 38 mA on a 4.5 volts with getting only a little bit warm (without any heatsink mesurements) and has about the same brightness as an ARC LE. I think 35 - 40mA is about the right current for a good brightness.

Therefor for such a conversion one should have a DC-DC converter with at least 200mA output current to use 5 white LED's what is the minimum of LED's I want to have in my Minimag. Better would be 7 LED's what should be possible in this diameter.

1. Which of the DC-DC Converters would you use?

2. You wrote that a few of the components could be eliminated. Which ones?

3. I know that that some other color LED would need less volts. But my prefered colors white and turquoise need the higher voltage.

4. In your easy conversion you remove the plastic reflector. How do you switch on or better off the Maglight? In the normal state the reflector is doing it. Do have a tailcap switch? And where is such a switch available?

1. Which chip. Let's see. If it's going to fit inside an AA mag light it's got to be small. (I still like the idea of making a barrel extension sleeve.)

The max757 is good for as much as 200 mA (100 mA for best efficiency) and 727 mW but it is kind of big, so that takes us to the max867.

First thing is to decide how many mA per led. You want as much light as possible without making much waste heat.

Looking here
LED caving light

Let's say 30 mA per led or P = .030 * 3.6 = 108 mW

Max power for the max867 looks like 471 mW, but the data sheet
max867
looks like the output current limit isn't much. Maybe only 10 mA optimum.

max867 summary

I guess that one's no good for multiple leds.

Here are all the max step-up chips:

Go here and click on step-up

I'll try to print it out and study it one day at lunch time. See if you can find one you like and we can talk about it here. I'm studying this too. I want to get something working on my breadboard and just let it run for a while.

So far I'm thinking about 8/PDIP but maybe the 8/SO.15 which is half the size would work too. They make a small breadboard adapter called a surf board that you solder it too. You need a really thin soldering iron and a magnifying glass or maybe that self-aligning solder paste stuff in the link above. That's why I like 8/PDIP.

2. Eliminate components. A little while ago we made a two transistor step up circuit. It works well. It's the one in the brinkman light.

Two transistor circuit

Based on experiments from there, I'll bet you could get rid of 1) the input filter capacitor, 2) the output filter capacitor and diode together, and 3) maybe the reference voltage capactor. The feedback resistors and inductor are needed. This would be a good breadboard experiment.

3. Do you have any turquoise leds? What does the beam pattern look like? How do they compare to the Nichia whites?

4. Mag light switch. I'm working from memory. I don't have a mag light here with me, but I think just the silver plastic reflector comes out and leaves the switch and head still fucntional. Like this:
Mag AA lens view with 2 leds

It's a journey.

Other idea. An energizer four AA double barrel #D420BP will work with 2 AA batteries and then you can use the other barrel to hold circuitry or a third battery. Some day I may get one of those and take it apart. Other people here seem to like them for conversions. The head is good for plugging leds into and you can modify the switch somehow.