Emisar D4, a tac light..?

LED Flashlights – General Info
21

Don’t know what happened there. I didn’t “resurrect” this thread. It was at the top of the “Recent Posts” list when I posted in it.
Someone either posted before me and then deleted their post, or some other shenanigans took place. :question:

Again, I love the D4. Great light. But it is not really best-suited for use as weapon-mounted-light. There really is no debating this. In a high-stress situation requiring IMMEDIATE action (when your fine-motor skills go to crap), you don’t want to be fiddling with an e-switch and/or trying to remember how many “clicks” it takes for something. Also, you want that light available NOW, not in 2.5 seconds, or with a “soft on” UI, etc. A good WML is also designed/constructed for hard use. While the D4 is well built, I doubt it’s been subjected to a rigorous T&E phase with impact/drop tests, etc.
I would rather use the right tool for the job, especially when it comes to something that you may have to depend on, IMO.

I don’t remember anyone mentioning remote pressure switches previously, but I am not really a fan of them either. However, a quality one that has been designed and tested for a specific light is going to be far more reliable and rugged than an a cheap e-switch. Also, the reason I mentioned a preference for a “shrouded” tail cap switch is to mitigate the possibility for accidental activation.
Even a non-shrouded tail-switch is leagues better in that regard than a fully exposed side switch.

Personally, I don’t think a shotgun is the best choice for HD either. Of course, it’s always best to use what you know and are proficient with, but at CQB distances the shot spread of a typical shotgun is still pretty small, requiring you to aim with relative accuracy to hit your target. They are also bulky, heavy, slow/awkward to load, and have a very low round capacity. Unless it’s an SBS, it’s not going to be the easiest to maneuver inside a structure either, nor easy to operate with one hand if needed. They are also LOUD. If you fire a shotgun indoors without ear pro, you WILL have immediate hearing loss/ringing, which can be very disorienting (and possibly result in permanent hearing damage). The best guys around at using/manipulating shotguns are seasoned 3-gun competitors. If you ask any of them what they would recommend for an HD gun, I doubt any of them would say “shotgun”. :wink:

A 4000 lumen light can certainly take out your OWN night-adapted vision temporarily as well. You accidently hit that switch close to a white wall, your night-adapted vision goes to crap for several seconds too, and if you keep the light on, you give away your position (hence the concept of “light discipline”). Also, a high-lumen flooder is great close in, but probably not the best tool for PID past 20 meters or so.

The preference for primary cells for use in a WML (specifically for HD) instead of secondary (rechargeable) cells is not so much a concern about the need for “prolonged power” but more about having full power when it’s needed, even if the batteries have sat for an extended period of time. Primaries have a much higher energy density, and a much longer shelf life.

There is a shooting range/club in Miami with a full-blown multi-story “tac village” with night ops that is open to the public? Where is this? What is the facility called?

Fair enough. It’s certainly better than nothing (if used properly), and I suppose there are plenty of worse options out there.

Respectfully, I have doubts on this. If by no other evidence than your choice of light mount. :stuck_out_tongue:
If true, I’d be interested to know specifically which of the “best” dedicated WMLs you have tested/compared to the D4, and how/why you concluded that all of them were inferior in that role. :beer:

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Never said dedicated wmls. But have used/owned off the shelf Klarus, Nitecore, Surefire, Zebra, Olight, Armytek, Fenix. Since joining the forum have modified many many lights and tried lots of them on different firearms. They all work well, just the ramping ui, size,durability, and brightness of the d4 makes it outstanding for in home SG defense, imo.

What would you suggest for a shotgun in home defense light and mount,.? keeping in mind, budget', and the very very if ever occasional use it might see. Not looking to spend more on a light then the gun is worth.

Just tried a club members surefire ($400) on his Remington. It replaced the complete pump stock with a plastic light holder that had a 600 lumen light with 2 modes, 200/600. It was nice, a little bulky and uncomfortable for me.

For my old eyes, lighting up a room like daylight allows my most important weapon between my ears to get all the clear data it needs to quickly make the decision if deadly force is needed. And to make sure I don't miss a second or 3rd intruder in the corner of the room that might not be illuminated with a semi spot/flood beam 600 lumen light. Make no mistake, the D4 lights up the WHOLE room completely bright, and probably semi blinds anyone its pointed at for at least a few seconds if not more.:BEER:

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The potting material will cause the thermal regulation to react much quicker. Potting will also reduce the recovery time after thermal regulation is no longer needed.

When I build a light, I add thermal insulation under the MCPCB platform and install a heat sink/spreader just above the driver. This insulation will slow down the thermal chips response time. To correct this, I add an electrically isolated copper strip to the thermistor running to the outer edge of the MCPCB platform. This gives the thermal chip a somewhat direct thermal path to the MCPCB temp without exposing the other driver components to excess heat.

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Just saw this post, a little late, sorry. Thanks for this info.

So in other words you insulate the driver from heat and add a ‘remote’ heat sensor piped directly into the chip. Very nice and good thinking.

I suggested something like that in the d4 thread. Not the way you did it with the copper strip(great idea). With the D4(and all lights constructed like it) delay/big variation in consistency in heat step down especially from a cold start to hot start, I felt a better system would be a nice upgrade. I asked about a remote heat sensor for the chip, but was told not available. Looks like you created a nice remote sensor system.

You mentioned thermistor, I don’t know much about these drivers but was told the heat regulation was on chip. Didn’t understand how the chip could ’sense heat on its own. Didn’t realize they have a separate thermistor connected to the chip.That explains a lot.

Your system must react very fast to heat changes with its dtp to the thermistor.
With a ui constructed to take advantage of this fast response time you’d think sw engineers could make a ui that will allow ramping up/down to much better correspond too the heat limits allowing the light stay as high as possible as quickly as possible. With the much better heat sensitivity, it maybe will allow close to the max junction temp safely, for a longer hi output run time…?

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Nice website, and very nice lights you make, might have to pickup 1 of your drop ins.

In the highlighted circle, is that the copper strip you're talking about..?

I

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I really mis-spoke about the separate thermistor. If a driver’s chip has the heat sensor embedded, and I say ‘run the heat pipe to the thermistor’, it mean ‘run to the MCU or wherever the thermistor or sensor is located’.
The current drivers I use that are thermally controlled use the embedded sensor. Several years ago, I use a driver that did have a SMD thermistor which I could remove and mount remotely. I would elevate just under the driver platform… this worked very well while keeping the driver cool.

How well the ‘heat pipe’ will work really depends on the thermal control logic. One of my favorite thermally controlled drivers (DrJones’ H17F/lucidrv) doesn’t perform any better with a heat pipe.
Although I can’t see his code (proprietary), I have a good idea of how the thermal logic works because I’ve tested so many of the drivers.
The lucidrv doesn’t make any thermal adjustments in the first 20-22 seconds. I’ve determined this because I can measure the current to the emitter… nothing happens until about 22 seconds. I will let the driver make considerable thermal adjustments. Then I will turn the light off and back on immediately. Even though the temperature is still high, the driver will deliver full power again for 22 seconds.
When the thermal control kicks in, it’s rate of step down appears to be the same no matter if the temp is 10C high or 50C high. The driver takes a temp reading, makes a small adjustment, another temp reading, another small adjustment and will keep doing this until it reaches its target temp. The polling time and the adjustments are always the same until it comes close to the target temp.

If the light is running in direct drive or 1/2 direct drive, it will be ready to step down after 22 seconds… with or without a heat pipe installed (if potted). If it is running in step 22 (3.04a) with a default temp setting, it doesn’t need to step down for several minutes any, so there’s plenty of time for the sensor to read and react to the temp.

When used in a triple or quad, the lucidrv thermal protection is too slow -not because it doesn’t ‘sense’ the heat, but because it waits before starting it’s adjustments, then the adjustments it makes are too small for the amount of heat generated. This will cause the thermal protection to over shoot the optimal output level for the set temperature. This will cause the ultimate output to be very low… much lower than necessary. Still, it does what it needs to… it protects the emitters. The thermal protection works perfectly with a single emitter… I’m sure that’s how he designed the logic.

I’ve just received some drivers with ToyKeepers’ Crescendo firmware. I’ve built one test unit, but haven’t determined how it works thermally yet. It may benefit with the installation of a thermal heat pipe. I could just look at the code, but it’s Greek to me.

Potting will ensure the thermal sensor (wherever it’s located) reacts quickly. The thermal bridge made by the potting material is about 40x better than air alone. I have noticed that the thermal regulation of a potted light is much faster and more importantly, much smoother with less bounce than a non-potted light.

So, the thermal bridge will probably help with the reaction time of a thermally controlled driver if it’s not potted, but without potting the light, the conductive copper strip may be difficult to install without risk of shorting something out.

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That’s good to know. That matches my H17F test results too, but I haven’t tried putting one in a smaller or higher-powered host to test if it increases the adjustment speed. It sounds like it does not, which would mean the algorithm is not proportional. In my testing, it took about 8 minutes to ramp down from full power to a stable sustainable level, but on many triples and quads, that would need to happen an order of magnitude faster.

Crescendo uses a PD algorithm. P for proportional; the adjustment speed depends on how far it is beyond the target temperature. D for derivative, meaning it tries to guess what the temperature will be in the future, and adjust based on that. Steering into the turns, basically. It would probably benefit from a heat pipe.

Some of my newer code uses a PID algorithm. The “I” term basically acts as a noise filter, and helps make the proportional response more accurate. However, I think adding up several measurements may also sometimes cause integer overflows, so I need to adjust things more to prevent that.

Anyway, about the original topic, I’m not sure a D4 is a good choice as a weapon light. Its springs don’t have enough flexibility to absorb much shock, so I’d go with something with longer bouncier springs.

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Emisar D4, a tac light…?

NO, tac lights are black.

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That is a racist insensitive comment that cannot be tolerated. LOL

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Sorry, I mint have tail switches.

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No worries, I was just having fun with it.

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Guessed that, I was thinking about all the goofy ads about tactical lights. I am tired or my response would of been more thought out.

It does have tactical momentary. But no disorienting strobe.

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Most people like no blinky modes.

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FYI the two cerakote image links you include in your replies are both 404, and Chrome has eklundconstruction.com flagged as a deceptive site and wouldn’t even load this BLF post until I bypassed the warning.

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No. It is simply not a tactical light suitable for mounting on any weapon you depend on for saving your life or the life of others. It is also not suited for offensive type military WML uses.

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Well it’s not designed as a tac light, that’s true. And the interface really isn’t suited for tactical use.

But that said, if you just want something compact to hang on your weapon that is very bright, the D4 will probably work. It does have double-springs, is compact, and very bright.

If I were using it for this purpose however, I’d probably open it up and pot all the electronics and solder bonds with Arctic Alumina for greater shock resistance.

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Those improvements would help that you mentioned, but my D4 will never see the end of any of my long guns.