DST using 3 18650's (Finished)

Finally, every inch of this long light is contributing to projecting photons. The finished light looks completely stock on the outside, except for a dedomed xml2 and AR lens.

Distance to the pine tree is about 250 feet. The tree is about 70 feet tall. It looks close to house, but it about 150 feet behind the house from the perspective of where the picture was taken. The emitter is just a touch too far behind the reflector when the below picture as taken (was about 284kcd at the time). Pictures are slightly darker than real life. Mouse over is Stanley 1M Series Lithium Ion Spotlight (54kcd unmodded):

The build is almost finished. It holds 3 unprotected cells (18650) but can run on 1 or 2 cells too. So it can run on Li-ion, Lipo's, Ni-mh, Ni-cad, etc. 4 AA's fit without a spacer. The nice thing with 3 cells is that the individual cells don't have to work very hard to provide 7 amps. So high performance cells are not required.

One of the cells passes through the switch housing. It uses a very short tail spring. The light has about $30 in parts as follows:

I did also fry 2 xml2 emitters being careless in a rush late one night, but they are not physically part of the finished light. Right now running about 7 amps to the emitter and getting about 300kcd (has measured as high as 319kcd). Not bad for a budget light.

Tail current with 3 cells, charged to 4.15 volts resting, is:

High - 2.9 amps

Med - 1.25 amps

Low - .3 amps

It is handling the heat well. No hint of angry blue in the beam. This light handles an MT-G2 at 6+amps. So this is not a surprise.

Some Build Details:

Unfortunately, the DST pill has too narrow a driver bay and the walls are not thick enough to bore out for the Manafont 3T6 driver. So the following was done to beef up the pill's heat sinking and to accommodate the 3T6 driver:

  • Lopped off the driver tower
  • In the hollow portion of the remaining pill, pressed in 3/4" aluminum bar stock
  • Drilled a hole through the pill and bar, and pressed in a 3/8" copper bar stock
  • Counter sunk the back of the pill to add a new driver bay. Counter sink includes a 1/16" grove around the parameter to press the below 3/4" copper coupling into (overkill).
  • Cut a short piece of 3/4" copper coupling and split lengthwise to open up diameter. Also cut a copper disk to press into the split 3/4" coupling.
  • Used silver bearing solder to reflow the new driver bay to the copper bar. Also, reflowed an xml Noctigon base on the top side of the pill.

This is a pic of the pill assembly before the reflow. The copper coupling looks beat up because it is a reject from another project. Just happened to be about the right size.

A simplified version of the above could be made if one didn't want to drill, etc. I noticed some thin aluminum tent tubing fits snugly over the driver tower. The tower could be cut short and then the tent tubing would press over it. To hold the driver, a 3/4" copper coupling could be inserted in the tent tubing. Not as secure, but should do.

The split in the driver bay will allow easy adjustment current to the emitter via a trim pot. Stole this idea from RaceR86's T13 mod. The driver bay is solid and will not be going anywhere. Stress tested it several times. The driver board will break before damage to the pill happens. The switch section screws up around the lower portion of the driver bay. Covers the lower portion of the driver bay.

Here is the driver fitted be soldering and filing down to the size of the pill.

The trim pot really is accurate at dialing in current in this driver. Just don't crank it all the way up like I did and fry an emitter. I did start out lower, but got impatient adjusting. As can be expected by the specs, most of the trim pots range is not used in this application.

This driver gives rock solid current delivery with both 2 and 3 cells. I got no differences in emitter current with stock resistors and also with trim pot turned up to 7amps using 2 and 3 cells.

Also sanded of the anno in the ledge that is in the DST head that the pill screws down against. Also rapped the threads in copper tape. Really snugged up the fit. Both of these mods help facilitate heat sinking to the head and exterior fins. I copper taped all the DST threads.

Here is the preliminary quick-and-dirt "tail spring". It is equal to a very strong spring and provides a very good connection. It works real good right now because the light is currently a twistie. I think I will stick with this same design, but make a nicer version.

This blurry shot shows were the cells sit in the tube. There is no driver spring. The tail cap screws all the way down.

Switch (Sorry for the sideways pictures):

There are more switch pictures at Post 53.

can’t wait to see that baby completed :bigsmile:

+1. Lots of creative thinking going on here. Is the led on a copper star?

Wow, this is going to be awesome. :slight_smile:

LIKE! :)

MRsDNF, that is a copper star, Noctigon..

That is my super observant powers at work again. Yes you are 200% correct. Problem is it wont be the last dumb question I ask. Thanks.

Thanks guys. Added a few more pictures so that the end objective is clearer.

You could drive a 6V MT-G2 in the DST with this setup?

Ohaya wrote:

You could drive a 6V MT-G2 in the DST with this setup?

Should work. I haven't tried 3 cells with MT-G2 yet, but it works fine with 2 cells. I intend to do this to my MT-G2 DST too. I have really become attached to that light. I use it more than all of my other lights now when it comes to outside.

Great work! I like it!

-Garry

And I bought an extra Defiant 5C to do this in the future, Yours will be better!
So many leaves, so little time

+1 Super nice!

You did great! I like the way you solder the parts.

:bigsmile:

Thanks for the positive comment and encouragement guys.

I worked on it more tonight, but I ended up blowing 2 emitters. This driver can really deliver the juice. I just reflowed a new emitter and dialed back the trim pot a lot, but its late and I need to crash. Hopefully, it will be at some semi sane level of current next time as this project is starting to go from budget to not so budget now.

Got it running tonight. That trim pot is real accurate for dialing in current. Set it to about 6.75 amps. I say about because I measured current with the pill out of the light. There could be resistance in the light that brings in down. There could have been resistance with the DMM that could have under measured (doubtful though).

The hot spot is much smaller now. Measured a 237kcd. Hopefully, I can improve that. I will hopefully take some pictures this weekend.

Wow! Draw measured at the emitter? Sounds like unless that’s already perfectly focused, there could be more …

Yeah, that is amps at the emitter. Not sure if it is fully focused or not yet. Probably not far off.

I just took it for a walk last night. It's a light saber with some flood narrow faint spill. One has to be careful to not continually get dazzled by the concentrated beam/hot spot. Running it on low is about the only way to walk around with it on.

I will do this mod to my dedomed MT-G2 DST. Will only have about half the throw, but it will light up a big area. That is more my type of light for general usage. It won't run on Ni-mh, etc though.

Edit: Flood was the wrong word above.

Nice work!

Will there be some beamshots comparing it with one of your MT-G2 lights in the future?? ^^

What kind of current did you fry the emitters at?

I'll try. I still don't have the night time beam shot skill.

I don't know the current the emitters fried at. Here is what a happened. I'll admit ahead of time that I was not exercising the due care (from the emitters' perspectives). I was trying to dial in the trim pot. Started it at the mid point and got 4.3amps. That is pretty much the stock current. Expected that given the trim pot's specs. Started the process of turning a few turns and then reconnecting cells and testing current. After many iterations, I became concerned that I had a bad connection or bad trim pot. So, not wanting to unsolder the trim pot and test it, I decided to just short the trim pot, connect cells for a split second to see if current jumps. The emitter flashed the moment I connected (2 cells) and then the emitter no longer worked. No current flowed after the flash and I didn't see the current reading at the time of connection.

The second emitter. So I knew I had a good connection to the driver, but maybe the trim pot didn't work. So I turned the trim pot all the way up. Based on what I read about the lowest resistance the trimpot was capable of, I figured I was going to end up there anyway. Connected the cells and the same exact thing happened again. Flash, no longer worked, no current flowed after the flash, and didn't see the reading at the moment of connection. Probably didn't even register a reading as fast as it happened.

I know, I know. I knew better. Was tired and impatient. I need to not mod when I feel that way.

EDIT: I will add that this driver is deceptively beastly. I don't know how far the trim pot is from max, but it is further than I expected. Looking at the voltage sense resistors, they are physically large. Don't know the size spec, but they dwarf the typical sense resistor you see on drivers. I'll add this. I have a TN31 that I have to fight to get it in 6 amp territory. This driver gets there easy and is rock solid. The current doesn't fluctuate. I need to find a way to make this driver a slave to another MCU.

Thanks for the info! :)