TK's Emisar D4 review

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ven
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How about the best $40 light on the planet Smile

Agro
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finges wrote:
Agro wrote:
What’s the recommended way of adding GITD to this light?
Has anyone found a matching GITD o-ring? How about a glow paint?

Buy a sheet of gitd foil. Then you can cut two stripes around 3mm wide and stick them around the inside of the light. There are two flat walls where you can stick them to.

Thanks for the suggestion. How about heat resistance? How do I find the best quality foil available internationally without huge shipping costs?

On another topic, for the last several years I got one good light. Peak Eiger. Unlike D4, it had a springless battery tube. The existence of spring means that one has to do a lot of unscrewing to stop the battery from making contact. It seems that it’s best to unscrew the head because it has shorter threads, but that’s still a bigger job than it would be springless. Furthermore, it’s impossible to fully remove power
It impacts D4 UI in 2 ways:

  • It is a necessary step to reliably access the max-7135 mode
  • Locking the light. I used to make a long turn, make sure that battery rattles slightly and new I did good. D4 has a 6-click. It’s actually more ergonomic because I don’t have to check for rattling. But I know I will forget how many times I need to click. And fiddling with the light in the dark to be able to actually make use of it doesn’t sound like good ergonomics. And even less like fun. It may be possible to loosen the tail cap enough without separating the light into pieces, but I’m not sure how reliable it is (minimal turn make the light blink as if I just connected power) and since the washer is at the wrong end of the threading, the light stops being waterproof.

djozz
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Unscrewing the tailcap only very slightly already locks the D4 out because contact between tube and tail-pcb is broken, it is not needed to break contact between battery and spring. It works very reliably and is not even dependent on intact anodisation so when that wears out the lock-out still works.

Good enough for me Smile

Agro
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Definitely, thank you.

BeardedRaleigh
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ven wrote:
How about the best $40 light on the planet Smile

Fact.

Slow is smooth, smooth is fast.

Fuzzylogic
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The Nichia 5000K tint is a bit cooler than I expected. Compared to a few of my other “neutral whites” this feels more on the cooler side. Not a complaint just an observation. Actually when I put them side by side, the Nichia feels the most “neutral” while other “neutrals” feel slightly warmer. I’m starting to like warmer tints so I might have to pick up an XP-G2 5D next.
My only complaint it that the anodization on my 18500 tube is already scratched from inserting and removing the Convoy clip. I guess I can’t expect too much from a $5 tube. Might have to sand down the entire groove to make it look better.

RollerBoySE
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ToyKeeper wrote:
10+ fast clicks then press and hold: Thermal config mode, added in v2. Hold the button until it gets to the action you want: Blinks out current temperature limit. Release button to exit with no changes, or keep holding to continue.

Is a zero shown as something similar to half a blink?
At least I suspect that to be the case on mine.

hank
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Has anyone thought of building a flashlight with a phase change heat sink?

https://www.1-act.com/products/pcm-heat-sinks/

https://www.1-act.com/led-thermal-management/

Quote:
In most general lighting applications, the heat must be dissipated through natural convection heat sinks (where radiation may play a significant role) to meet acoustic noise restrictions. However, the thermal management requirements of emerging high intensity LED lighting products often exceed the practical limits of these passive cooling strategies. Integrating heat pipes, HiK™ plates, or vapor chambers with the heat sink can reduce the LED temperatures, and allow current heat sinks to handle higher heat fluxes.

Something that would contact the smooth outside of the light and carry heat away from it (better than your hand) would be useful.
Swords with gauntlet hilts that wrap outside of the grip area illustrate how it could work.
https://www.google.com/search?q=gauntlet+hilt+sword&source=lnms&tbm=isch...

Here are some modern-tech designs: http://www.windrosearmoury.com/zc/index.php?main_page=index&cPath=71

maukka
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RollerBoySE wrote:
Is a zero shown as something similar to half a blink? At least I suspect that to be the case on mine.

That’s what I suspect as well. Got 50 a couple of times and 51 was clearly different.

Agro
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I took D4 for a short walk (buying flashlights is good for health!), have some things to report.
1. Like said already many times, knurling is missing.
2. I noticed a quirk in the UI. If I ramp the light up to a fairly high level, wait for thermal management to restrain it an start ramping again, I expect the light to smoothly change output. It jumps to the previously set level and starts ramping from that.
3. A weird software bug:
Sometimes the light doesn’t notice that I cut off the power. It doesn’t blink on power-on and doesn’t reset mode to 350 mA. Happened twice accidentally, I couldn’t reproduce. Then after playing some I tried to do it again and it happened: there were no blinks. But then I noticed more: now I can reproduce it at will, it happens every time. I think this may be because I have not turned the light on since it happened, there’s some flash state that makes the light not notice and turning it on resets that.
4. I like the tint.
5. Very floody, but still less than I was afraid of.
6. Everybody knows it, but the output is good. Smile

hank wrote:
Has anyone thought of building a flashlight with a phase change heat sink?

https://www.1-act.com/products/pcm-heat-sinks/

https://www.1-act.com/led-thermal-management/

Quote:
In most general lighting applications, the heat must be dissipated through natural convection heat sinks (where radiation may play a significant role) to meet acoustic noise restrictions. However, the thermal management requirements of emerging high intensity LED lighting products often exceed the practical limits of these passive cooling strategies. Integrating heat pipes, HiK™ plates, or vapor chambers with the heat sink can reduce the LED temperatures, and allow current heat sinks to handle higher heat fluxes.

Something that would contact the smooth outside of the light and carry heat away from it (better than your hand) would be useful.
Swords with gauntlet hilts that wrap outside of the grip area illustrate how it could work.
https://www.google.com/search?q=gauntlet+hilt+sword&source=lnms&tbm=isch...

Here are some modern-tech designs: http://www.windrosearmoury.com/zc/index.php?main_page=index&cPath=71


I thought about that. There could be a minor LED temperature improvement by replacing solid trays with vapor chambers. Or actually large portions of head. It could also make powerful lights (D4 counts) slightly shorter. Likely too expensive to be worthwhile.
You could use heat pipes to spread heat over large heatsinks. It could make them more effective, making monster lights a bit brighter.
You could also use something like paraffin wax to increase thermal capacity and thus increase turbo duration.
saypat
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ven wrote:
How about the best $40 light on the planet Smile

wondering if anyone really only spent $40? Add batteries, spare tubes…. Wink

ven
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saypat wrote:
ven wrote:
How about the best $40 light on the planet Smile

wondering if anyone really only spent $40? Add batteries, spare tubes…. Wink

Ha ha good point! Well i spent $42 with the tracking , think I may be the only one with no 18350/18500 tube though………….for me the 18650 is compact enough and it eats through one of those fast enough Shocked

Thumbs Up
hIKARInoob
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ven wrote:
saypat wrote:
ven wrote:
How about the best $40 light on the planet Smile

wondering if anyone really only spent $40? Add batteries, spare tubes…. Wink

Ha ha good point! Well i spent $42 with the tracking , think I may be the only one with no 18350/18500 tube though………….for me the 18650 is compact enough and it eats through one of those fast enough Shocked

Thumbs Up

Same here, only standard 18650 format. But I did get all three colours though. Interestingly I like all three colours, and I’m glad I got them all.

BeardedRaleigh
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ven wrote:
saypat wrote:
ven wrote:
How about the best $40 light on the planet Smile

wondering if anyone really only spent $40? Add batteries, spare tubes…. Wink

Ha ha good point! Well i spent $42 with the tracking , think I may be the only one with no 18350/18500 tube though………….for me the 18650 is compact enough and it eats through one of those fast enough Shocked

Thumbs Up

18650 only for me as well. It does eat juice like its free. small enough to loose already!

Slow is smooth, smooth is fast.

BeardedRaleigh
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Also, we’ve got 3 reviews on MTN!!!

Yes one of them is mine…(pops collar) Wink

Slow is smooth, smooth is fast.

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Mtn was out of Green 18350 tubes last week.I hope they they get some in soon so i can try out these new aspire 18350’s i have.

hank
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Well, the heat sinks made for RC engines would clamp onto the smooth flashlight surface, with a dab of thermal goop:

https://www.google.com/search?q=model+engine+heat+sink+clamp

I wonder if there’s a way to use the waste heat — does anybody make micro- or nano-sized Stirling engines?

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djozz wrote:
hank wrote:
Well, the heat sinks made for RC engines would clamp onto the smooth flashlight surface, with a dab of thermal goop:

https://www.google.com/search?q=model+engine+heat+sink+clamp

I wonder if there’s a way to use the waste heat — does anybody make micro- or nano-sized Stirling engines?


I would sink it into my girlfriend, she’s always cold. Party

Yikes let’s keep it PG.

Slow is smooth, smooth is fast.

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Fuzzylogic wrote:
I’m not interested in large multi-cell light…for now. This D4 is actually all that I need (I tell myself repeatedly).

lol! Big Smile
winspiration
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Can this take Olight batteries?

BeardedRaleigh
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winspiration wrote:
Can this take Olight batteries?

I would stick with unprotected flat tops. Keep your springs in good shape.

Slow is smooth, smooth is fast.

Ronin42
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From OP

Maximum cell length: 67 mm
(protected cells may not fit)

Battery: One 18650, 18500, 14500, 18350, or 16340 cell (with matching tube)

From me
goofy proprietary cells designed to not work in normal lights (no)

(“It’s good that most people can’t remember their previous lives. Otherwise
things would be a lot more complicated than they already are.”
Ajaan Lee Dhammadharo)

hIKARInoob
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BeardedRaleigh wrote:
winspiration wrote:
Can this take Olight batteries?

I would stick with unprotected flat tops. Keep your springs in good shape.

Yes. I’m using button top GA now, but definitely prefer, and feels better using a flat top cell.

djozz
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BeardedRaleigh wrote:

Yikes let’s keep it PG.


LOL, ignorant me did not intend my remark that way, I will remove it!
winspiration
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BeardedRaleigh wrote:
winspiration wrote:
Can this take Olight batteries?

I would stick with unprotected flat tops. Keep your springs in good shape.

Isn’t protected safer though?

hIKARInoob
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winspiration wrote:
BeardedRaleigh wrote:
winspiration wrote:
Can this take Olight batteries?

I would stick with unprotected flat tops. Keep your springs in good shape.

Isn’t protected safer though?

Generally yes, but protected cells often don’t work in a light like the D4. There are two reasons:

1) It just doesn’t physically fit. Either it’s too thick, and/or it’s too long due to the protection circuit. The D4 probably won’t contact when tightening the tailcap.
2) 99% of protected cells are going to trip most likely due to the current that’s too high. Only recently you have 15A protected cells; those might work… if they fit… But they probably don’t fit anyway.

BeardedRaleigh
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djozz wrote:
BeardedRaleigh wrote:

Yikes let’s keep it PG.


LOL, ignorant me did not intend my remark that way, I will remove it!

Haha. I figured. I had to say it still. Lol.

Slow is smooth, smooth is fast.

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Finally, I receive 18500 tube from intl-outdoor. I like it better than 18350, Tiny size but still have enough length for nice grip! Too bad, there is no good 18500 battery on market right now Sad .

(WB 5000K): XP-G2 3D, Nichia 219c, XPL-HI 3A

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Agro wrote:
Played a bit with thermal regulation. It’s less smooth than I expected, the output stays visually stable, makes a jump, stays stable for another while, jumps again etc. Also, I noticed that if I heat it up a bit, turn it off and start at full output, the peak temperature will be much higher than originally. Also, I think it may be exceeding the level that I configured….or maybe my burnt fingers got more sensitive Wink

It can drop down in large steps. Stepping back up only goes one small step at a time though.

The step-downs could be made smoother with a bit more code, but it also has a high risk of introducing bugs. I actually tried it at one point, but the direct approach was too buggy and the indirect approach was fragile. So I went with a more robust but also more visible method.

Also, the regulation is not based on the current temperature, but on the predicted future temperature. This means it’s sensitive to the rate of change. If it’s below the target temperature but rising quickly, it will step down pretty quickly. But if it’s above the target temperature and falling quickly, it won’t step down (and may even step up a little).

When it first turns on in turbo, it will generally exceed the target temperature before it stabilizes. This is because, even with the predictive algorithm, thermal lag still delays the measurements too much to avoid the initial peak. Basically, thermal regulation is rather unpleasantly like trying to steer a fast-moving cow around a hairpin turn on an icy race track. While wearing someone else’s glasses.

hIKARInoob wrote:
Edit:

The higher the temperature increase rate (dT/dt), the bigger the difference between desired maximum temperature (what you felt), and actual max temperature value (Tmax set by D4).

Yes, it’s based on the predicted temperature, not the current temperature. This helps it compensate for thermal lag. Without that, the racing cow was slamming into each turn’s crash wall a lot harder.

Agro wrote:
2. I noticed a quirk in the UI. If I ramp the light up to a fairly high level, wait for thermal management to restrain it an start ramping again, I expect the light to smoothly change output. It jumps to the previously set level and starts ramping from that.

The light makes a distinction between the actual ramp level and the target level. The button sets the target level, while thermal regulation can change only the actual level. This allows it to step back up when the actual level is lower than the target level and the temperature is no longer too high.

To change the behavior, the ramp button code could perhaps use the actual level instead of target level, when they’re different? I doubt it would be a difficult change… and patches are welcome. Smile

Agro wrote:
3. A weird software bug: Sometimes the light doesn’t notice that I cut off the power.

If I understand correctly, this isn’t a software bug. It means the power wasn’t disconnected long enough for the driver to lose power. To make this happen, do the following:

  • Ramp to a low level.
  • Click to turn the light off.
  • Wait at least 6 seconds so the light will enter sleep mode.
  • Loosen then tighten the tailcap quickly.
  • Notice that the light doesn’t blink. Click to turn it on, and see it’s still at the last-used level.

This happens because the standby current is so low that it is able to tolerate short interruptions while it’s asleep.

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djozz wrote:
USB charging.

I wonder how hard it would be to add an inductive charging circuit in a tailcap. I really don’t like poking holes in a waterproof light for USB ports.

Not that I have an inductive charger… but it might be a nice way to do these things without incurring the usual problems associated with built-in charging.

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