TK's Emisar D4 review

Will need to read more up on it. The D4 is def bright. I read that my Maxa Beam does do damage to the eyes but from what I understood that was not because of the intensity but the fact that short arc creates a lot of UV light and not all are filtered out by the glass. The maxa is going to be locked in my weapons cabinet tho as it’s def not something for a kid…

I’m with toykeeper on the part about parenting. This is why I do let here play with it while I’m watching and explain that it’s dangerous to point it directly at someone and that it’s very powerful so she can not adjust it with the button. This is teaching here about the dangers but still allowing here to explore. There’s lots of things that are dangerous when not handled properly so they might as well learn instead of avoiding… But if short therm exposure of the beam can be harmful it’s not worth the risk of a kid not listening because there is no second chance with the eyes.

She has weak AA and AAA flashlights but it’s more fun to borrow mine…

Maybe I should make a separate thread instead off taking this off topic :zipper_mouth_face: ?

I don’t know if it’s allowed with links to another forum but this thread below was a good thread to rise awareness about lasers and might be somewhat relevant to powerful leds also so I’ll post it. Mods delete if it’s not allowed. This was what’s got me thinking about eye safety. It didn’t have a good outcome but it shows how fast things can go bad.

Small die laser diodes will always be more dangerous than LEDs because of their insane candela/lumen ratio compared to LEDs, especially at long distances. They can do much much much more damage at similar power levels.

Even I’m not keen on the Emisar D4. Its potential for damage, and huge heat generation means it’s not a light I’ll be carrying, ever. I prefer a regulated 1000 lumens from a quad LED setup, for very long runtimes of regulated brightness.

Eye damage? Not that I’ve heard of. I have 210 lights and the majority are heavily modified, folks around here know by now that I can’t help but modify a light for all it’s worth… never heard of anyone actually having damage from a bright flashlight. Sure, if you look right at it from up close it hurts and you look away, but it’s not lingering and causes no “damage” to my knowledge. Sure aren’t as bright as the sun day in and day out… :wink:

Hi Wight, long time no see! :slight_smile:

Adults have to use common sense, Li-ion cells and bright flashlights are not toys for children to play with. Like guns and knives, screwdrivers and wall outlets, common sense must prevail…

No, not eye damage of course.

I was writing about physical damage, like on your skin, your backpack.

And no! Actually, on very close distances, most high power flashlights actually have higher intensity than the sun. This is how I can see my modded BLF Q8 in the brightest part of the day, and when I pull it straight to my face, it gets very hot quickly.

Welcome back! (for a little bit)

The stock D4 has a standby drain of about 0.02 mA. If I recall correctly, it goes into standby about 6 seconds after turning “off”.

When the light is awake but has the main emitters off, like between blinks in beacon mode, it uses about 4.5 mA.

The stock light’s moon mode is higher than that, like maybe 7 mA or so. I forget the exact value, but the moon level is higher than I wanted.

In newer firmware, I reduced the power used while awake. To do this, I made it under-clock the MCU at low levels, and also made it go into an idle state between interrupt events. So by reflashing a stock D4 to the latest Anduril, moon mode drops to about 1.7 mA and the between-beacon-flashes power use drops to like 1.1 mA. Also, it goes into standby a lot sooner after going to “off” mode. In most cases, standby is immediate.

To reduce standby power, you can change the fuses a bit while flashing. Basically, turn off BOD and it’ll drop standby from ~0.024 mA to ~0.002 mA. This change doesn’t really affect battery life much though, and mostly just determines whether the light will reboot after changing the batteries, or if it can go without power for long enough to swap the cells.

I’m not sure what exactly was done to eliminate ringing, but if I understand correctly, it’s a resistor on the FET control pin to soften the edge of the curve a bit. It may be possible to determine how this works by looking at a recent driver from MtnElectronics or Emisar or Texas_Ace, but I don’t really know enough about circuit design to explain it.

The voltage divider can be eliminated entirely on most 4V linear-driven e-switch lights. There is no need to use pin 7 for that any more. Eliminating this reduces standby drain quite a bit compared to older designs, makes PCB layout easier, and frees up a pin for other purposes. The MCU uses VCC on pin 8 to measure voltage.

To use thermal regulation, at the moment, it needs a tiny25/45/85 MCU with a sensor built in. For running Anduril (or other FSM-based interfaces), I’d suggest tiny85. I plan to add support for tiny84/841/1634 sometime too, but I’m not sure when.

One other thing to note is, for e-switch lights, the UI development is now a lot easier than it was in the past. Take a look at the FSM UI toolkit if you have any interest in making or modifying interfaces. This allows people to define interfaces in a much more intuitive way than before, and makes it fairly easy to support a variety of different hardware.

Also, aux LEDs are a popular thing now. They’re blingy like tritium vials, except they don’t wear out and they can be turned off or turned down.

You’ve probably missed other things while you were gone too, but I’m not sure what.

There is no rule against outside links on BLF. :slight_smile:

As for lasers… I have a list of “cool toys which are too dangerous for me to own”, and high-powered lasers are on that list. I could buy or make one, and it would be glorious, but someone would probably get hurt. Many of the high-powered ones are bright enough that even just looking at the hotspot on a wall, without protective goggles, can cause eye damage.

Yes, indeed, Lasers are another story altogether! I have a 3.3Watt Blue laser that can burn a yellow jacket nest from 25-30’ away! It WILL burn a blister on your hand in less time than you can jerk away from it, so the eyes are definitely in danger from something of this power. These should be treated just like a gun, locked away from children and monitored to the same extent. Very dangerous stuff, the high powered laser.

Can’t the thermal level just be set way down so it doesn’t get hot? I really liked to have this kind of power available but it’s indeed to hot. I always unscrew the cap before I pocket it due to the heat. The D4 is also very good looking :stuck_out_tongue:

No, better not. These are not toys. A 500 lm XM-L with a 20mm head diameter is safe though, with protected batts….won’t get too scalding hot also. If you get an AA NiMH XM-L, best. About 200-300 lm.

I nearly got blinded with a HID and 55W bulb, with 75W ballast so that one was overclocked. Actually for that one wasn’t even the hotspot issue, but even the spill is sufficient to screw up your vision for a good couple of hours. The light accidentally fell on its side and my eyes directly caught the spill just some 15-30 cm away. I had a bright spot vision right in the middle of my field of vision for a few hours. Forget about the blink reflex or look away reflex, they don’t help enough.

The 55W bulb just has an arc gap of 3mm and you are doing like 5000 - 6000 lumens easy. Go calculate the surface luminosity.
eg relative to a XHP 35 is 3.5mm x 3.5mm. How many lumens is that, should you even catch the side-spill up close?
Not sure how many lux is the side spill that close though, havent measured that. Don’t get mixed up lux with surface luminosity though, i sometimes mix them up.

I also have a couple of lasers small to big weak to powerful, those are even worse as the laser lights are literally infinitely point source wrt LEDs. 5mW in certain scenarios can cause eye damage. Their low divergence means their beams stay dangerous, so forget about being 10m away from the laser, coz even the reflections might be dangerous.

That point source light would be focused onto the retina, and these point sources burn your retina the same way as a magnifying glass + sun combo.

With a real intense LED high cd hotspot, you’d get an even bigger hole in the retina wrt your eyes catching the spill, if both are pretty up-close.

One thing that also needs to be mentioned, is that laser light is coherent light. It loses very little energy or get “out of focus” (lack of a better word) after passing through the lens, a lot of energy is left to be focused on the retina. LED “non-coherent” white light behaves a bit more differently. But still get enough white light brute force candelas onto the pupils, bad things would happen still no matter how it’s badly focused onto the retina and energy transmission to the tissue cells. :slight_smile:

Oh btw, if anyone wants to know a number, once i had some free time and tried to measure my cheapest and lowest powered 50mW greenie from several tens of metres away, typical aperture size (no beam expander) and no real effort done to focus it accurately at that distance also. It’s works out to be 8 Million cp on the lux meter, seriously not very high. I’m not sure how the green light is being accurately measured by the lux meter, but well it’s just a number. If it so happens that you focused it to be around 1m (for burning purposes) and it feel from the tripod and with sheer luck the beam gets through your pupils, it’s well well above that 8 M cp. Up close, that “8 M cp” is still from an infinite point source of light that the eye lens can focus more or less nicely onto the retina, unlike a big reflector HID or BLF GT hotspot, even if we keep the lux readings on the pupil diameter to be the same for both LED and laser light sources. It’s this point source that significantly makes laser light so much more dangerous even with the same lux, coz of the way it’s focused on the retina to be a point source image.

PS. It’s actually the thermal and photochemical effects that the laser light has on retina tissues. Another issue is that green causes more damage to the retina (red) than red laser light, something like green lasers can pop red balloons and it’d take much higher powered red lasers to pop that same balloon.

Oh yeah, my youngest (5 yr old) has his own Xeno E03. A XM-L 20cm head light. When he’s alone he uses the NiMH. If i am with him outdoors, i’d pop in a protected 14500. Safe enough.

A D4 would be too bright too dangerous up close, shd the power settings be accidentally set. Young kids have short hands, really too close for comfort.

I can’t remember on the other thread, did you get the latest gen Maxabeam or the earlier ones? 12 Mcp or?

I am willing to bet that 12 M cp hotspot + pretty much point source at longer distances with that relatively small 5 inch aperture, if your eyes do get caught within that ten plus metres (not sure when the hotspot would really start to become focused though), is dangerous and has potentially enough lux/cd at that 10+ metres with that 5-inch aperture literally becoming as a point source of light, to cause permanent damage be it UV or visible in times shorter than your blink reflex. Even if not permanent, it’d take a fairly long time to heal (not hours definitely).

Generally, UV and IR radiation causes damage to the cornea/lens, while visible to NIR causes retina tissue damage.

Give these things to a normal person who always jokes around, i am also willing to bet that he or she would point it at someone’s eyes. I already had that happen with my “only” 3.8 M cp HID during a flashlight meet. Never ever hand over a laser pointer to a layman without a safety brief even outdoors where reflection risk is low.

edit - who wants to volunteer to get hit by a Mateminco MT35 Plus’ hotspot at just a few metres where it’s beginning to focus and has the highest lux. :smiley:

Similarly, the new Maxtoch L2K LEP light, with 2000 metres (not sure what is the cd for this, been several years since i did such calculations) and front aperture of just 60mm, is going to be pretty dangerous as well, even though pure cd numbers are not high relative to say a BLF GT. It’s both a function of the cd and also the aperture, that determines how it’s going to be finally focused onto the retina. It’s also possible due to LEP technology that it is already focussed into a tight beam within 1 metre! :cowboy_hat_face:

PS. Sorry i may not be very good in conveying all my thoughts and tehnicalities as English is not my first language, I hope it does not confuse more. :stuck_out_tongue:

I look at atomic blasts all the time and I don’t have a problem. I just watched 10 of them on YouTube and my eyes are fine!

Sorry, I’m trolling since I can’t go fishing today

Welcome back ! too :slight_smile: . Where have you been ?

Sorry, not enough time to tidy up this quoting but:

When we moved on from the Attiny 13 to e.g. the 85 (via the 25) it was found that they became more and more susceptible to the FET/LED current switching spikes, that messed them up.

DEL sorted this out by properly de-coupling the MCU from the main power rail. With a 5R in series, and 100 nan across the MCU.

Also added a pull-down to the FET gate drive to properly define it.

Here is a link to the schematic of the current FET+1, which might work:

No voltage divider needed now, we first bumped up the values x10, which helped a lot, but then eliminated it altogether by letting firmware do a sort-of double measurement (TK can explain). Combined with getting rid of the voltage divider, and the OTC (ugh), this means the MCU can now do all the switch timing in firmware. And learning how to use the Attiny’s power saving capabilities.

Many designs now use an e-switch rather than a clickie. But both are valid.

Quiescent current is now so low that you can even change cells without re-booting.

Moving to e-switch drove quiescent current drain development (always on).

There has been a retrograde trend to lighting up switches, tailcaps, aux-led boards etc which has wasted some of these improvements, but some seem to like this sort of flashy nonsense.

It has all become very commercial now, hardware designs are not usually shared (even though they are still mostly derived from your and Comfychair’s pioneering). Commercial contracts are at stake, and any constructive criticism is not usually well received.

Oh wow

Got my first D4 in a couple of weeks ago. Ordered from intl Aug 31, got it about three weeks. Went for a grey (green not in stock) with XP-G2 S4 5D 4000K partly for cost, but mostly since the XP-L and Nichia were only available in 5000K at the time (5000K is too cool, if I have a choice, and 3000-3599K is ideal). Also, I have no interest in pounding Nichia 219s to death when I have a nice Jaxman E2L 4000k triple (2.1A?) if I need a lot of high CRI light.

Lot of info in this thread about XP-L and Nichia, very little on the XP-G, and even less on the 5D, even though I think there was a list where it came in 3rd or 4th most popular. Bought a clamp meter that cost almost as much as the light, which makes both items a great deal. I get a bit over 11A with fresh 4.2V 30Q or HG2, and about the same with a 4.1V Sanyo NSX. Suits me. I stay under 3A per emitter, and it's still total overkill on turbo: eye searing (closed eyes), skin burning (the beam or the light), and fire starting (if the paper is a dark color). I get 11s turbo before 1st stepdown using a 49C thermal setting. 59C, but the light reads about 10C too high. The outside of the light gets to 52-59C, depending on conditions. Got 8A with a generic 2500mAh cell, 8-9A using a 20A DMM with short 10awg leads and internal 10mOhm shunt.

I'm a total Zebralight nut. SC600, mkIII HI, mkIV Plus, SC60,62,64. Not counting the AA ones, two of which are high CRI (the XM-L is the worst white-wall tint I've ever seen, so I can see why Emisar isn't using Cree for CRI). I love everything about them except for their complete disregard of my battery terminals in the SC52,53, and 64. The 63/64 really should use the D4's tail spring. I'd suggest it to ZL, but I've already complained multiple times about their battery abuse, and I have to believe they know about BeCu springs. In the meantime some 0.1mm copper foil on the abusive spring suffices.

So, I just got the D4 because it was a cheap experiment, and so many people raved about it. I'm almost embarrassed to say, like so many in this thread, that the ZLs are all on the shelf. The SC64 is a much better EDC because of the size and the clip (even if the clip does wiggle a bit), and the Plus is effectively as bright as the D4 with much better efficiency, temperature control, and moon modes. But, the D4's tint is so much nicer, and the UI is so much fun. Reminds me of my old keychain Photon Freedom, a SotA 10 lumens back in the day. I don't know if it's the tint or the UI that's more of a factor, or the feel in the hand, but I really love the D4. To throw in the iPad-size work bag, I found a LED Lenser PX20 (red/white LEDs) holster fits the D4 perfectly. Shouldn't need a tailcap lockout, but it really would melt the black nylon if turbo came on.

So, I love it, but what's a one-sided review. So...

To gripe, I'm not a fan of the well-executed but too-simple driver. ZLs efficient 12V boost driver is incredibly impressive engineering. The D4 is just, well, something that can be easily put together with off-the-shelf parts. The mechanical part of the design, especially the springs, took some ingenuity, though. Maybe as much as ZL, given the price. And the springs are flat-out superior to ZLs struggle with too-stiff springs and pogo pins. I don't know why that's given them so much trouble. The body design is basically a ZL copy made easier and cheaper to manufacture. I'm not griping about the $35-40, though. $90-100 ZLs do give me pause, $60-70 ones are worth it.

For the UI, the only real complaint for practical use, is that it memorizes turbo if you shut it off in that mode. I like the three blinks in the ramp, and really don't get the analogy with a car where the engine stutters at efficient RPM. It's not a car. It has nothing the least bit in common with a car. Even calling it a "hot rod" only makes sense to me in that it is cylindrical and if you run it long enough on high, it's like holding on to the wrong end of a torch (the flaming kind). Cars have lots of controls and indicators. This has a button and a light. And, if we're going to gripe about questionable turn-off times, the dark time to turbo after a double click while on makes a lot more sense to me. The double-click event and timeout explanations cover / justify that, though. The tactical mode is completely pointless, since a couple of flashes and it's off doing something else. I'd ditch it entirely and use 4 clicks for lockout.

I'm not planning to get another D4, but 9/25 I ordered a green D4S with 4000K XP-L. I'd have much preferred 21700 or 2x18650 to 26650, but it looks like a comfortable size. And IT HAS AUX LEDs. I wasn't even considering it 'till I saw a picture with the cyan pseudo-tritium, after that I couldn't order fast enough. I could see maybe another D4 if green or another _smooth_ color comes out, like purple, and if some other 4000k (CRI?) option comes out. Nichia is just a bad match for a linear driver, but maybe XP-L, preferably Samsung. Don't expect either, any more than I expect a 21700 tube for the D4S.

So, the light and reading all of this thread have been a ton of fun, thanks BLF.

On the subject of children: one suggestion I would make is to put a frosted lens in the light. I’m not mad keen on the idea of diffusion film, since a child might find a way to remove it.

If you have a spare lens for your light, you can frost it with fine wet-or-dry sandpaper. Just sand it until you’re comfortable with the result.

As others have said, a Convoy S2+ with one of the less powerful drivers might be a good option for children you can trust not to mess with the Li-Ion cell. Convoy sell spare lenses, so you can get an extra one to do the sandpaper frosting thing on.

Other ways to reduce beam intensity are to use a larger LED - XM-L instead of XP-L, for example - and to use an orange-peel reflector.

For small children, I’d definitely stick to low-powered lights that use AA cells, and I’d still be inclined to frost the lens for good luck.

The D4 has taken the place of my ZL SC62d for EDC. I prefer the ZL size and stock clip, but after adding an Overready clip it rides nicely in my pocket. The tailcap has a tendency to scrape the back of my hand when I reach in the pocket but negative reinforcement has changed the angle that I use when reaching in.
I’d prefer to be able to carry the ZL but I’ve got Anduril on the D4 and find it perfect for my needs.


Photo of D4 with clip?