Ultimate small Maglite mod summary

I've spent a few weeks reading through this board trying to make sense of what mods are available for various small flashlights, concentrating on the various small MagLites sitting in my desk drawers. I thought I'd put together in one place everything I've learned.

For the Maglite Solitaire: (1 AAA battery):
The physical size of the light and modest power capacity of the single AAA battery limit the number of mods that have been done for this light. The options are:

Mod 1: The hottest ticket is to simply go buy an ARC AAA flashlight, it's almost the same size but has an electronics package to boost/regulate current. About $28:
http://www.arcflashlight.com/

Mod 2: The simplest mod. Replace the AAA battery with a garage door opener battery (MN21, 12V), and lengthen the spring in the tail of the flashlight. You can then replace the bulb with a T-1 (3 mm) LED (it plugs right in), and you'll have a pretty good little LED light, though the battery will only last an hour or so. Also, the light will dim noticeably after a few minutes of use, but will perk back up if you turn the light off for awhile before using it again.
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=14;t=000247

Mod 3: The Satcure circuit.
A single transistor step up circuit. I haven't been able to find any mention of efficiency for the circuit; anyone know?
http://edusite10.tripod.com/led3/onetran/single_tran.html
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=000474
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=000388
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=000436

For the Mini-Maglite 2xAAA:
There don't seem to be many good mods.

For the Mini-Maglite 2xAA:
Lots of good mods. This is rich territory. Some of the experienced modders really prefer the Brinkman legend:
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=14;t=000275

Mod 1 - N Cells and an LED. Probably the simplest mod, though I think it significantly overdrives the LED (70-100 ma???). Replace the bulb in the head with your favorite 5mm LED (it plugs right in, if it doesn't light you have it in backwards). Then:

Ver 1. Replace the two AA cells with three 'N' cells. The N cells are skinnier than AA's, so it works best if you find some kind of tube to put the N cells in that keeps them from rattling around. Three N cells are also shorter than two AA's, so you'll need to either install some kind of spacer or replace the spring in the tailcap with a longer one.
http://www.elektrolumens.com/MINIMAG_LED/MINIMAG_LED.html
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=14;t=000242

Ver 2. Replace the two AA cells with two 'N' cells, and one AAA cell. You still need the tube, but you no longer need a spacer.

Mod 2 - Put in a regulated current source.
1. Opalec NewBeam. $28
A complete drop-in replacement for the light/reflector assembly of a Mini-Mag, uses 3 white LEDs.
http://thelightsite.cruxial.com/reviews/opalec_newbeam.htm

2. MagPill (Illuminator Pill) from Lambda. $24.50
A step-up kit that replaces the switch assembly inside the head of your maglite:
http://home.mchsi.com/~lambda/minimag.htm
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=8&t=000472

3. MadMax-ADJ from Dat2Zip $12 + Luxeon Star
An efficient, slick kit that requires minor assembly:
http://home.attbi.com/~theledguy/hobby/flashlight_modifications.htm
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=8&t=000528

4. ZLT (++, CCR, CCR-2) from Mr. Al, Dugg, Mercator et al.
Do-it-yourself with extensive discussions of circuit theory, etc., in the threads:
http://www.5thcolumn.org/zetex/project/
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=000983
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=6&t=000422
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=6&t=000432

5. Lambda Illuminator
A complete flashlight.
http://home.mchsi.com/~lambda/lambda1.htm

Anything else I've missed?

/frank

Frank, you sure have done your homework. This should be posted in the faq's section as a permanet referance.

I think mod 2: refers to mod'ding a maglight solitaire or many single AAA flashlights but not the ARC AAA.

As I recall, you also need a resistor since 12 volts directly across an LED is not recommended.

Great list. I agree, for many newcomers this would help.

WayneY

Both Mod 2 for the Solitaire, and Mod 1 for the 2xAA technically require a resistor installed. Both overdrive the LED without it. However, I read a lot of reports from people who did it without the resistor (as have I) and everything worked just fine, and NO reports from people who blew up their LED. YMMV.

/frank

Hi Frank

Congratulation! You really have done a great job with this list

Don't forget the 2 LED Solitaire mod. Details here and some additional updates/details here .

Re. the 12V Solitaire mods in general:
While the LED's don't exactly blow up if the resistor is left out, it does initially drive the LEDs way over spec when running a fresh battery w/o a resistor. I had better results using a resistor, even with the 2 LED version.

Jack,

How big of a resistor did you use for your solitaire mod?

Thanks

I used 47 Ohms in the 2 series LED mod, and 100 Ohms in the single LED version. Even with those values, the LEDs are still overdriven when the battery is fresh. Probably double those values would be more appropriate for a fresh battery. Those 12V 'remote control' batteries lose voltage pretty quickly though, so I wanted the resistors to be somewhat undersized.

It's pretty simple to add a resistor to the battery spacer. Someone suggested putting the resistor inside a bit of drilled out 3/8" dowel rod, and then using the coiled up resistor leads on both ends as the contacts. I tried this, and it works very well. You can even make two or three spacers like this with different resistor values, and can then change to lower resistance (or no resistance) as the battery begins to wane

Oops, while wandering through my bookmarks, I found a good mod for the 2xAAA Maglite using the Maxim Max1759. One or two White LEDs, includes PCB diagrams:

http://mikro.e-technik.uni-ulm.de/persons/lares/LED_flashlight_V2.PDF

/frank

Originally posted by Frank Schwab:
Oops, while wandering through my bookmarks, I found a good mod for the 2xAAA Maglite using the Maxim Max1759. One or two White LEDs, includes PCB diagrams:

Click to expand...

<font size="2" face="Verdana, Arial">The MAX1759 seems not to be a very good solution for a two cell flashlight because of its high minimum input voltage of 1.6 volts. So you can't suck your batteries really down. I suppose its efficiency also isn't very brilliant (didn't see the figures/diagramms in the data sheet). For me it seems to be a rather old chip. Another point: The 10uMax housings asks for a very experienced hand to solder it ....

Instead this IC I would recommand using eg. a MAX1722 which goes down to 0.8 volts input voltage - and it is in a much easier to solder SOT23-5 housing. If you can select your LEDs for eg. [email protected] volts you also can use the MAX1724 (same familiy as the MAX1722) which has a fixed output voltage of 3.3 volts and therefore uses some parts less.

Also the LT1932 IC from Linear Technology would be a better choice for two or three LEDs as it goes down to 1 volt input voltage and is in a SOT23 housing too. The LT1932 is current regulated so from this point of view it would be the better choice. You then can connect the LEDs in series and have the same current through all LEDs. I made very good experiences with the LT1932 in Minimag/Micromag-Mods (Minimag: 2 AA, Micromag 2 AAA) with 3 LEDs (they really also fit in a Micromag ) and it also runs very good with NiMH which provide only 2.4 volts even though the LT1932 works better with higher input voltages.

Added later:
------------
I almost have forgotten to mention the ZXSC300 IC from Zetex (the one used for the well known ZLT+ boost converter) which also is current regulated and in a SOT23 housing. This one would also be a very good choice especially because it also runs down to 0.8 volts input as the MAX1722/1724 ICs do.

Frank, In the spirit of your "Mod 1", The easiest modification for the Mag 2XAAA is to give it away, and put the pocket clip on your Arc AAA.

remuen -
whether it's the best possible choice or not isn't really the issue - it's a pretty good mod for a light that I found no other mods for. Now, being an Engineer, I can appreciate your arguments (and in fact have a Max1795 in my hot little hands that I have big plans for. The uMax package doesn't intimidate me, but the 0.85V startup spec intrigues me).

Besides, 1.6V isn't a big problem for a two-cell flashlight. By the time you've drained an Alkaline (or a rechargeable for that matter) down to 0.8V, it's pretty much dead. Most major battey manufacturers use 0.8V as the "dead" value in their spec sheets. Drawing down to 0.4V will give you a few more minutes of runtime, but nothing spectacular.

/frank

Originally posted by Frank Schwab:

... and in fact have a Max1795 in my hot little hands that I have big plans for...

Click to expand...

<font size="2" face="Verdana, Arial">Frank, interested to see some figures with the MAX1797? Here they are:

</font><blockquote><font size="1" face="Verdana, Arial">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">
IC MAX1797
Board Rev2A
Date 06/30/2002
Cin 10uF Ceramic
Cout 22uF Ceramic
L 6.8uH (Murata LQH55)
R1, R2 250kohm pot
Ripple@3Vin 71mV with MrAl's Ripple Tester
Startup 0.71V

Input Output Eff
U I U I
(V) (mA) (V) (mA) (%)
---------------------------------------
3.0 0754 3.70 518.0 84.7
2.4 0909 3.60 493.0 81.4
2.0 1044 3.55 454.0 77.2
1.6 1005 3.39 346.0 72.9
1.5 0996 3.36 321.0 72.2
1.2 0968 3.23 242.0 67.3
1.0 0951 3.14 191.0 63.1
</pre><hr /></blockquote><font size="2" face="Verdana, Arial">The MAX1795 will probably give you some better efficiency results as the MAX1675 does compared to the MAX1674.

I used this MAX1797 for some of my LS Minimag mod. I tried to convert it into a current regulated boost converter using a high side current sense monitor from Zetex but I didn't bring it to work (after a first test I didn't try this again because I had no time to work on my circuits ...

I like those numbers! The efficiency doesn't look great, but good enough for my purposes. Of course, I'm only looking for 30-90 ma output. Looks like its got the balls to do that with no sweat.

Thanks,

/frank

Awww, Frank, you missed my mod!!

It was a UKE-2AAA mod using a SatCure type circuit (full version with all the capacitors, etc.) arranged to be the size of a AAA battery and encased in plastic.

The UKE-2AAA has a side-by-side battery configuration and this mod sits just behind the lamp assembly (which has been replaced with a LED of course).

It has an initial output similar to the Arc-AAA, but seems to dim steadily over its 5-7 hour life, ie. no regulation, just straight boost. The SatCure circuit will run on as little as 0.6V and will run on dead batteries that wouldn't even power the Arc, but the light output is understandably dim by that time.

When the batteries are fresh, the LED light is 2/3 as bright as the original xenon lamp. The original lamp will run about 2-3 hours on 2xAAA, steadily dimming and yellowing all the way. The LED mod will dim, but not yellow, and do it over a 6-hour period with 1xAAA. The case is not touched, so the light is still waterproof to manufacturer specifications. The entire lamp assembly is replaced when the bulb burns out, which means that one can still change back to the xenon light if needed.

Well, you didn't list a link for it, now did you?

I was gonna update this in the near future with links to Dat2Zip's latest Badboy and Madmax stuff anyway, so if you find the links, I'll include them.

/frank

Been lurking around here a few weeks now and recently signed up. This is probably my fifth post so I'm still a newbie.

I've played around with the Zetex mod at http://www.5thcolumn.org/zetex/project/ and looked at the app note on Zetex's website on driving the Luxeon. I noticed everyone incorporates the rectifier diode and the capacitor in their circuits. Why not just drive the LS directly from the inductor? Efficiency goes up nearly 10% (in the low 90%). I've used this method and cannot tell the difference using the shottky and cap. Yes, I've built two circuits with and without. What you get is an LED driven with pulses in the 20kHz or more range. Your eyes CANNOT see this pulse rate. I actually looked at the waveforms of the switcher on an oscilloscope to verify the switching rate. (Yes, I'm a nerd engineer.) What you gain is the elimination of the Shottky forward voltage and the losses due to the ESR in the caps. You also eliminate two parts. So, all you need is two IC's, an inductor, and a sense resistor (wire), four parts in all. Got the IC's from Digi-Key, two Lumileds as free samples from Future (our company has a major account with them so I get a few perks) I've got this circuit powering up a Luxeon in a modified Surefire 6Z (I like the tail switch) and also a two C-cell Pelican light. The C-cell pelican light has over 17 hours use (I stopped when I lost track of time)and it still has nearly the same brightness as the Surefire mod with one DL123 lithium with a battery spacer. 17 hours on the same set of batteries with almost full brightness, I'm happy. Boy I love these LED's! As far as efficiency, I estimate I should get 19-20 hours using 90+% efficiency and 8300mAH capacity of C cells. Did I say I love these LED's? Boy I do love these LED's!!! Now I need to go make some more mods...

CM,
Do you have any runtime graphs or data for your circuit? I've been using a lot of Zetex circuits for my mods, but if I can eliminate a couple of components and raise efficiency, then I'd be very interested. Does eliminating the cap and diode have any adverse effect and the regulating? thanks

I apologize for not having any quantitative data (graphs, we all love graphs here). I will work on getting a proper setup for data gathering since I myself am curious also.

As far as adverse effects of eliminating the cap and diode in the Zetex circuit, there is none. In fact, it is beneficial, IMHO. Here's why. When you have the cap and diode in the circuit, the LED is always forward biased because when the inductor discharges, the diode conducts, forward biasing the LED. When the inductor is charging, the cap is dumping its charge across the LED. Now let's take out the rectifier and cap. The LED is only forward biased when the inductor is discharging. While the inductor charges, the LED is OFF. Why is this better? LED power dissipation. In the former, there is a higher AVERAGE voltage across the LED. In the latter, the average is lower. So now you may ask, "Won't I get less light output with less power?" Yes, and no. Your eyes only sense the peak of the emission. Since the LED is switched on and off several hundred kHz (I made an error in my last post), you do not "see" when the LED is in the OFF condition, it's happening too fast. I present the ubiquitous flourescent light as an example. It is powered by AC which reverses direction at 60Hz. We cannot see this since most eyes cannot detect such rapid changes. Now the LED is switched about 10,000 times faster so we won't see that either.

I'm guessing the Zetex circuit (the one in their website app note) was designed by a power supply engineer who is used to designing supplies for CMOS circuits. Almost all (Linear Tech, National, Maxim, etc) DC-DC switchers have this Shottky diode/cap arrangement at the output. This is because the application demands low ripple voltage. In the case of LED's ripple voltage is really a don't care. So, bottom line, you can get rid of the Schottky and cap. Hope this helps.

I wil try to post some quantitative results, or at least some beam shots. I just got a nice Arc LS I've been dying to compare my mods with (the Arc LS is a very nice light). I'll probably stick to testing with AA's since I can deplete those in a reasonable amount of time. C batteries will take too long and I'm not going to automate this process; I'd rather spend money on flashlights ;-)

Cheers

CM

If white light output isn't a requisite, a very simple and fast mod I have done for a 2AA Maglite is to pull the bulb, and plug in a red or red/orange HP "traffic signal" type LED. If it doesn't light, turn it around 180 degrees and try again. No resistor, or regulator needed. The reflector will have to be modified, the rear part with the "fins" will have to be ground down, and the bulb hole enlarged to fit the 5 mm LED (I haven't tried a 3 mm in the AA lite). I have modded two for myself and several for friends.
Hint: don't use a Radio Shack red LED, it will become a dark-emitting diode in short order. The LEDs I use were from E-bay a few years ago, got about 600 of them for $30 at the time. The HPs are tuff enuff to take the overdrivin' and keep on shinin'. Similarly, a 3mm red LED of sufficient strength can be used in a 2AAA MiniMag. The red light is good for night vision preservation, and is bright enough for most uses.
InReTech also makes a plug 'n' play red LED (also white, blue and UV) plug-in for the 2AA. Either alkalines or NiMH AAs can be used in the light.
I also did up another mod using six HP red "oval"LEDs and a single round 5MM in the center, on a little round board. Sure, it works well, but it wasn't real easy. The seven LEDs are in parallel, I use the leads from the center one to plug into the MagLite's pinholes. It is impressively bright for a 2AA non-Luxeon or Lumiled modded light.

/ed in NH