Mod: Zoomie with MT-G2

Well, I did what I thought I’d never do, I stuck a MT-G2 in a zoomie. But in my defense this light is not for me, it’s for a fellow enthusiast for photography in dark places who want’s a wide zoomie that packs a bit of punch.

The zoomie host of my choice is this one: but someone pointed me to this one which appeared to be the same but cheaper:
They are however not the same. The FastTech light has a solid pill, the Banggood light does not. There are a few other subtle differences too, but not really worth mentioning. This mod I’m using the Banggood one because I’m out of the FastTech ones.

I build a few of these lights for others every now and then (this is the first with MT-G2 though) and have previously used Qlite drivers and stacked chips. I have managed to stack ’em but man do I hate it. As I had a trial version of the pro Eagle I got to making a four layer 20mm driver to suite my needs:

The main features:

  • MCU on the spring side, which means no more ripping pills apart to flash! Yippee! (Some of you kindly donated small Nanjg driver springs to me for this).
  • 15 x AMC7135 chips divided over four output pins of the MCU, meaning I can run any number of 1 to all 15 of them for constant current modes.
  • Single AMC7135 chip is on PB0 so I can PWM control it for lower modes.
  • Vias for all wire connections, with a through wire to the spring for spring bypass.
  • Zener ready with voltage divider resistors, zener diode and zener resistor all on the spring side so switching between zener and standard does not require dissassembling the driver from the pill.

As this Banggood light has a hollow pill I used Artic Alumina to stick some copper washers to the LED, then I filed out slots for the wires:

The plastic sleeve for the LED in this light fits over the MT-G2 perfectly! Where can I buy these? Haven’t seem them for sale anywhere.

Even though this light isn’t for me I still can’t stand the beam of the focused MT-G2 and can’t put my name next to it, so I put a ring of 18awg wire around the pill to prevent it from fully focusing (can be seen in the second driver photo). Works perfectly, keeping the LED just out of focus.

Features of the firmware are 30 second timeout for turbo (steps down two modes), 60 second timeout for high (steps down one mode) and voltage monitoring is tweaked so that when running on turbo, the voltage level for step down is the same is the critical voltage level for all other modes. I did this to compensate for the voltage sag on turbo with the 18350 cells I’m using. Running on high or lower modes is as normal, with low voltage step down and critical voltage warnings. The guy that this light is for does not want the light to shut off when critical level is reached because he might be in a situation where the need for some light outways the health of the cells, so I just put in a warning flash every 30 seconds when voltage level is critical.

15 x 380mA chips is enough for this light, it runs hot fast, and I don’t have to stack any chips! Do I need to stack if I should want more in the future? Hell no! I’ve made a purpose built slave board that fit’s right inside the pill with 16 x AMC capacity. The 20mm driver has two vias for slave board output, either on PB0 (PWM capable pin) or PB3 (which adds the chips to the string of 8 already on PB3 on the master driver).

I also replaced the switch with an Omten switch, potted the hole in the washers with thermal pads and greased the pill threads with thermal compound. The light is ready for him. It still has the plastic lens on it though. I’m looking for replacement glass lens for it and will send him one later if I find one that works nicely. Any tips on aspheric lenses that will fit? Diameter is about 28mm.

I’m happy with the result. It’s a good wide photography light that produces a good amount of light. I might make one for myself, glad to do it now that stacking chips is a thing of the past :slight_smile:

Nice mod, and thanks for the write-up :-)

Plastic lenses are usually optically better than glass lenses (in the budget sector that is). But they scratch over time, which spoils your throw eventually (flood stays fine).

wow nice mod!

Gonna make that driver available to the public? 0:) It looks soooo nice…… I love the MCU on batt side. Good job.

Props on putting in a ton of time to solve issues instead of just working around them.

I could make it available and maybe supply some firmware with it. Standard Star won’t work because I use different pins for everything. It’s also E-switch and off time cap compatible, but as I’m not a fan of E-switches and don’t need off time caps for these generic lights (using brownout method) I put that stuff on the reset pin.

I put that trial period of Eagle to good use. I’ve got more boards that I haven’t started on yet, once I’ve gone through them I could make them available if there is interest for them. Building and programming firmware for them usually makes me see things I didn’t first think off, so newer revisions are made as I go along. Although the original 20mm driver in this light works fine I have made a few changes to it for future builds. Once I’ve sorted all that stuff out I can make them available.

did you consider ahorton lens?
and more importan, are you planning on selling that great driver? (ready to install, I can’t solder into those tiny things…)
EDIT: you wrote previous post while I was looking for the link of the lens…

Cool man. You’ve only been here a year and you’re already doing super advanced stuff. The muliple channels and all that is amazing, but honestly just the mcu location has me drooling. :heart_eyes:

Ahh, thanks for the tip on the lens. Something to look into for sure! I gotta order one right away to test them out.

I could do that, pre assembled with working firmware.

Done the same thing to the 17mm driver and stuck 10 AMC chips on it, but it’s a different solution altogether with still a few things to solve. That’s my next hardware project… Still got the ATtiny85 firmware to finish… and the ATtiny24/84 based dual LED headlight I’m working on… and the etc etc… :slight_smile:

What a sweet mod. You have a very lucky mate. If you ever need another one(mate) let me know.

Nice Mod :slight_smile: Do you have any Beam shots comparing it to an XM-L Zoomie?

I didn’t take any. As I have limited the focus of the MT-G2 to be just out of focus I don’t really think it’s comparable to XM-L zoomies with focused beams. Anyone who has seen the MT-G2 fully focused in a zoomie knows why I did it, it’s horrendous! Now I have it just out of focus. The beehive lines are ever slightly visible but it’s still a solid beam. Too wide to be considered throwy though, but useful enough.

I’ll try get a white wall beam shot done with comparison shot of a XM-L2.

I've seen your work, so a picture of a white wall will be quite the reversal! :)

Why the use of Arctic Alumina instead of just soldering the copper discs together? Also, you called them copper washers. Does that mean the center is hollow?

By the way, great work on the driver board, and looks to be a great mod overall! Looking forward to seeing more board designs from you. Want something else to do? I’m wanting for someone to make a pcb to upgrade one of those cheapie 9-LED lights to XP-E2 or Nichia 119 emitters. I haven’t taken the time to learn how to use Eagle or design PCB’s or I’d do it myself.

Uhmm… yeah, that’s a good question. Didn’t think about that as I’ve never soldered pieces of metal together like that. I’ll try it next time. What works best, soldering iron or hot air? Solder paste or normal solder?

Yeap. I would have preferred a copper rod and chopped it up, or solid round disks of the right diameter, but washers where the closest I found with the right outer diameter. Washers are also usefull in triples where the wires go through the center of the MCPCB. I don’t have to drill out anything then, but on the other hand this is no triple. I’m open to any suggestions about the metal work, it’s not exactly my strongest side.

Thanks. Got more driver boards waiting to be assembled and tested, and plenty of coding to do, and tests with other components… so I have my work cut out… but can perhaps look into that PCB design later if no one else does.

I’m not sure about the little white disks that go over the emitter, but there are a couple of things that might work:

To solder a stack of copper disks/washers together, no electronics or anything, you can get them red hot with a torch — so you can use hard brazing (aka “hard solder”):

You can even assemble something using several different melting points, tho’ that’s not needed here.

Lots of silver in the solder.
It interpenetrates the copper a bit rather than just sticking to the surface. Gravity is enough, you don’t need a clamp with it that hot.
The moment the solder solidifies, drop the stack into boiling water. The flux just explodes off the metal leaving it much less likely to corrode over time.

Yep, use a torch to solder big chunks like that. Even a tiny butane torch should manage.

Stack them together with solder paste, clamp tight, then torch them. Then just clean up the outside with sand paper.

I took a crappy beam shot compared with two XM-L2 zoomies in focused beam. I didn’t bother getting my big camera out and rigging tripods and such as I had worked through the night on another project, so I just took a quicky with the phone. The two XM-L2s are both running at about 4.5A, and all lights are max focused. The beehive pattern in the MT-G2 is slightly visible so I think I’ve got the focus limiter just right. Any more and it goes downhill fast.

He wanted three or four modes so I put in four. The first lowest mode is a PWM controlled single AMC7135, mode two is one 7135 turned on, mode three is four 7135s on, and move four is all 15 7135s on. I got a 30 second timeout on highest mode, 60 second timeout on the next highest mode, voltage monitoring with a slight twist (when on highest mode, low voltage level is same is critical on all other modes). Short press next mode, long press previous mode. I’m using brown out detection for all presses, and then measuring with off time cap to detect short press.

I couldn’t decide what PWM level to set the first mode on so I made it user programmable by a simple user interface routine with presses. From PWM 4 to 160, then it starts to get too close to mode two to be of any use.

I had to do some serious byte hunting to fit it all, but managed to get the final version of firmware down to exactly 1024 bytes! I’ll be using this firmware for the rest of my ATtiny13A stash, then I want nothing more to do them.

While working on this light I find some things I wanted to improve on the driver board,so I’ve tweaked the design a little and ordered new ones from OSH Park. It’ll take a while before I have a final version of it, but hopefully I won’t need to make any more changes.

Very nice job, as usual.

I also usually don't quite focus my zoomies to 100%.

This is why I like zoomies for photography. At close I used it as a flood light, then at the far end in focused mode to “paint” the side of the carts. Taken on Saturday, not with the MT-G2 though. I wouldn’t bring a light built for someone else along on a trip like this. 80 meters of tight down-climbing rotten ladders (with backup ropes) in constant water, mud, and then wading in waste deep water for 30 minutes.

great picture!
I´ve been checking your flickr yesterday. It seems like you like abandoned places, don’t you?