Has anyone seen this new MJ MM led at the Sandwich SHoppe?

Is there any runtime/brightness info on this mod?


http://theledguy.chainreactionweb.com/product_info.php?cPath=48_56_83&products_id=940

I've lost my stock reflector, so this would probably be a good mod (I'm using the NIte-ize one now).

I've read about a MJ MM led swap before, but I wonder if this one is better/worse.

ALso wonder if it is any better than the (cheaper) terralux mods.

Hmmm, that sorta looks like the 4-die Cutdown SMJLED I just got from them. I wonder if its the same.

Is that smjled bright?

I don't quite get all the acronyms for these leds...

Sure looks like an SMJLED on a boost circuit puck. I would expect it to provide what the SMJLED-PR2 bulbs do, an ability to run NiMH's and low alkalines with good brightness. On fresh Alkies and lithium batteries, this LED works great without any boost, just trim the leads to 10mm, bore out the reflector and plug it in. I prefer it to the Nite-Ize module.


BUT - it may be like the SMJLED-PR2, in that when running fresh batteries, or lithiums, it will boost the current to the point that it may harm the LED. I have found the new SS single die SMJLED-PR2 bulbs will pull more from low batteries than the older 4-die bulbs. I try not to put anything in them that will deliver more than 120 ma from the batteries, which means I just use them for killing old alkies at 1.4 volts or less - and they are great for this! But even NiMH's drive most of my single die bulbs near 150 ma, and that can be tough on the LED over time. My older 4-die boosted bulbs are below 120 ma on NiMH's, though.

I would be very interested to see some test data on these, especially how much current they draw from various batteries.

Hondo

gunga, it is a 5mm LED, so it can't approach what a Luxeon can do. When driven very hard, they can get close, though. The problem is the heat at high drive currents will slowly cook them to where the light output is greatly diminished. Newbie did a torture test recently on the boosted bulb, which reinforced my suspicion that driving those with hot batteries was not a good idea. I believe early tests showed that the old single die MJLED was safe below 75 ma for lumen loss over time. That is the LED drive current, though, and what I mentioned above is current from the batteries, which I can measure easily. Since there is a boost circuit driving the LED, the LED current will be significantly lower than what the batteries are delivering, but at a higher voltage.


BTW, MJLED is an LED with the top cut off, devised by Michael Jordon (not THAT Michael Jordon!), to throw the light out to the sides so that a quality reflector can colliminate it into a tight beam with throw. The later SMJLED, or Super MJLED is the 4-die version, which was supposed to be brighter and whiter. I have found them to be bluer, actually, but to have higher Vf's, in my samples, so they tend to prefer hotter batteries. This is opposite to what they were advertised as, but I still like them for what they are, and they seem tough enough if you don't abuse them. Both are now available un-cut, with the normal dome shape for other types of projects, but I like them best in their cut form in a good reflector. I have also made some of my own direct drive "bulbs" by gutting an old PR2 bulb and soldering in one of these LED's so I can put them in non bi-pin bulb lights with fresh or lithium cells. But if you like the form factor, the MM does the best at throwing with these, I just like some of the floodier beams I can get with the faceted reflectors, and the knock-about factor of plastic lights.

Edit: I should mention that the whole beauty of these is the downright nutty long runtimes you can get with them. After dozens of hours direct drive, you can put your batteries in a light with a boost bulb in it and keep on going bright again for many, many hours. D-cell light runtimes have to be measured with a calandar, not a clock.

Hondo

Wow, thanks for all the info Hondo!

I guess I'll have to wait for more info on this actual led mod. I was wondering what the MJ and SMJ meant!

Interesting, so you think there will be more throw but less flood on this led? I can't tell from the pic what the reflector is like as well.

I just have an aging MM that I thought could use a nice, but not too costly mod. The terralux ones seem a bit costly (may as well buy a new light), and the nite-ize is a bit weak.

I'm planning on getting a cree fenix anyways, but would like to juice up the old dog...

gunga said:

Interesting, so you think there will be more throw but less flood on this led? I can't tell from the pic what the reflector is like as well.

Click to expand...

Actually, if it is done right, you should have the focussing ability of the MM back, unlike the Nite-Ize. At max focus, it should be very center focussed, but at flood, it likely will have artifacts and a hole, not smooth like your Nite-Ize.

Someone may know a good spot to get one, Lambda always had them, but you should be able to score a stock reflector, pre-drilled even, and then you could do a direct drive mod. By that time, though, you may not be cheaper that the kit you found.

The bare LED versions of the MJLED/SMJLED works from 2.8V to 3.2V. That means NiMH batteries will not work and alkalines will work only when fresh. Fresh lithiums shoulg not be used as 1.8Vx2=3.6V which is too high. The solution is to use fresh lithiums somewgere else for 5 minutes first. The advantage of adding a boost circuit is to allow regolar batteries to be used.

The Terralux TLE-10/20 produces a beam with an orangy red corona between the hotspot and spill light. I find it most annoying.

Here is the thread of the boosted SMJLED for the minimag:
SMJLED2 Minimag- New, Better, Brighter, Cheap, and Soon
http://candlepowerforums.com/vb/showthread.php?t=127907

I tried to catalog all the different versions of the MJLED/SMJLED here:
SMJLED confusion explained
http://candlepowerforums.com/vb/showthread.php?t=128865