I've been putting off this post for too long. Following that MT-G2 group buy thread, I noticed people are catching on, so I frantically went out and took some beam shots for this post :D
OK, so we have here a Small Sun ZY-T08 from Fasttech that on it's own is a very nice light. One day I decided to put the reflector over an MT-G2 I had mounted on my test heat sink. It took me two seconds to decide to put on in there. You'll see why when you get to the beam shots. ;)
The emitter of choice; a Cree MT-G2 5000k NW from Cutter. I picked up two a while back for my UF-T90, which turned out quite nice too.
I picked a driver that I thought would work from single-cell voltage so this would be a quick and simple mod. It didn't work out exactly as planned.
We're starting with this:
First thing; swap the emitter. This is straight-forward, so no progress pics, just the result. The main issue here is centering; In this shot I haven't figured it out exactly yet, but it's no big deal. The beam looks great even if it's off a little.
On to the driver. For this, I needed to keep the original as a contact plate, so I removed only the supply diode for the circuitry. Everything else stays. This way, I can revert to original (I never will, but the option is there).
I did a resistor mod to get up to around 4.5A. This host handles heat amazingly well. At almost 30W on the emitter, the heat is very well managed. The only issue is the surface where the star is mounted is quite thin. Some added mass inside the pill could help with this. I have not addressed this yet.
All done! That's it! simple as that. Right? Wrong. It should have been that simple. Turning on the light and it's bright for about one second, then it drops to low and flashes every five seconds.... What? Low battery, that's what! This 3V to 18V Buck-Boost driver does not work on a single cell! I am disappoint. |(
OK, so now what? My 2P 18650 light needs to suddenly be 2S 18650... Time for more modding!
If I reverse one of the cells and mod the switch, I can get this done! First the switch. I do not want the cells in parallel anymore. I use an X-acto knife, you can use a Dremel if you prefer.
I also do not want the switch to connect to the body anymore. I also need to connect the now-floating spring to the other side of the switch.
OK, switch end done. Now how to get negative to connect to the right place on the contact board. I started by relying on the lip around the edge, but that's a no-go. Too flaky, was disconnecting constantly.
I ended up adding a solder blob right where the negative end will be when tightened down.
To ensure this is always the negative end, I arbitrarily picked one side as negative and marked it. I tightened it down and transferred the mark to the head. That's where I added the solder blob. I just have to put the batteries in the right way each time, so I blacked out one of the battery symbols in the tubes to indicate the negative side.
Put in the cells, screw it together (always with the switch off), turn it on, and we have light; a lot of it!
Beamshots!
I'm very happy with how smooth and buttery the beam is. A very well defined hotspot, almost no corona, and an even spill all the way to the edge.
Indoor White(ish) wall beamshots, f/8, 0.5s, ISO100 Daylight
High:
Medium:
Low:
Outdoor Wall of trees, 18mm (29mm equiv.), f/5.6 4s, ISO400, Daylight
Here I compare the colour of the MT-G2 5000k to the XM-L2 6500k. The difference is very impressive.
Mouse-out ZY-T08, Mouse-over BTU Shocker XM-L2 U2 1C
In case there's any doubt, that dead grass really is brownish, not grey.
Output:
Updated July 29: The build has been improved by using a DRY driver and putting the emitter on a Noctigon DCB star. The build is basically the same (DRY is easier driver to work with), with a decent improvement in output (previous build was 1850 lumens and 28kcd).
Before lumens (stock 2.1A): ~600
Before Throw: ~48kcd
After Lumens: 2500 lumens after 30 seconds (freshly charged Panasonic NCR18650PDs)
After Throw: ~39kcd
Not bad. I like it this way. Now it earns its name; Small Sun.
Thanks for reading! searchID8935
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