Easy Mini MAGLITE 2-Cell AA Mod *now includes pictures and build details*

Nice work, but a 7135 is a linear regulator and won’t work with 2AA: voltage is too low (unless using 2AA single use lithium). When battery voltage drops below LED vF (about 2.6-2.8 volts here) LED will get very dim/moonlight.
Use a boost driver or just direct drive.

The driver is a boost driver. I took out the 3-mode chip and put the 7135 right before the LED.

I get mine from Sears. I wait for Sears to send me offers like “10,000 surprise points for purchase of $10 or more.” I combine those points with the 3,000 points I get every month for being a Shop Your Way Max member.

I’ve gotten several lights and other goodies for free or almost free that way.

I uploaded the wrong picture for the driver close-up. Here it is.

I’ll fix the OP now.

Wow.
Can you give us a macro photo showing that location on the board for that 3-mode chip?

OH, you just did! thank you, I can see the 7135, so ought to be able to figure this out.

Is there something similar you (er, I) can do with a single-mode driver? (those GearBest $2 zoomies say they’re one-mode in the description, which is not always reliable)

And I recall there are some variations in the 7135 chip — anything in particular to watch for?

Nice work. Congrats on the build. So the zoomie pill threads into the head?

I take it you sand the battery tube both for electrical contact and so that it can still screw all the way down? Or did you add a spring to bridge contact from the battery tube to the pill?

Got it, I misread; didn’t realize the linear was placed after the existing boost.

I bought two AA zoomies and got different drivers and LEDs, so unfortunately this is a one-off. I just placed an order for two more of the same lights from GB. Who know what I’ll get.

I did some research before putting in the 7135 chip. The boost chip looks like an ME2180.

ME2180 datasheet

This is a DC-DC boost converter that has regulated output voltage. Because of this, I can put the 7135 after it.

Some drivers use constant-current boost chip, such as the PAM2803, where the output voltage is not regulated but the current is. With those chips, the 7135 is not needed and the sense resistor can be changed to get the desired current.

Would it be possible to power an Attiny from the boost and use it to control the 7135? An mmu might be able to fit on a layout that small.

The pill just drops in but with very little clearance. I only sanded the battery tube for electrical contact. I was lucky that the TIR and pill combined fit perfectly. It took exactly one turn of the tube to turn on the light. Yes, I added a spring to the driver to allow it to make contact with the battery.

I don’t see why not. The ME2180 is designed to power microcontroller-based devices such as a wireless mouse. The tricky part is to make everything fit. What makes it possible is that the ME2180 only requires an inductor and two caps. Other boost converters chips require a schottky diode, sense resistor, and sometimes an FET.

If your interested in working on a much needed BLF driver design you might consider collaborating with some of the people Over in this thread A really good start would be to post a schematic of the board you’ve modded with the changes you’ve made. From there a schematic which includes the Attiny 13A for 16mm drivers or the mmu for smaller pcb’s can be made. It’s a small step from there to having one of the now more numerous members familiar with Eagle design software to come up with whatever board designs a bevy of backseat drivers can imagine. They need some help getting started.

The requisite information can be found in the ME2180 datasheet that I posted a link to, so I don’t need to create a schematic. I’ll post to that thread as you suggested.

It’s an interesting project in it’s own right and definitely targets an empty nitch in the growing list of BLF drivers. I can certainly see the possibilities for a number of different sized/different output drivers depending on AA, C, or D-cell use. Often we see drivers with the power section on one pcb and control on a second stacked pcb so that might prove an easy way to test by just powering a 105C board that has just one or two chips with one of these boost drivers. The voltage divider would need to be altered to feed pin 7 the proper voltage range and jumpered directly to B+.

If you do another could you post a pic of the driver in it’s stock form?

Sure. I ordered another pair of zoomies and hopefully one of them will be same 3 mode driver.

I’m considering opening up my BLF saber 1A(older thrunite T10) and looking at that driver since it’s survived using a liion for so long but the modes are off. Moon is good but med is hardly differentiated from high.

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Please don’t expect wonders, this is an old thread from 2015, but you are right, it’s still interesting. :wink:

You are right but…I found it too just now and…I have a couplle of AA zoomie + and old 2AAMaglite sitting around, so…
Thank you very much, I will give a try! :+1: