TK's Emisar D4 review

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Cpeng
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Pöbel wrote:
the finish before ano determines the surface after ano. A polished raw light stays polished and vice versa.

This makes sense as the inside of the tube is smooth anodized so its probably media blasted before anodize.

Cpeng
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Firelight2 wrote:
Cpeng wrote:
Has anyone ever figured out what the “grainy” finish is on the D4 and D1S lights? Its very unique and I can find no explanation of it anywhere, I have the white D4 and the grey D1S. I guess I want to know out of curiosity.

It’s just anodizing like on pretty much every aluminum light. However, there are different ways of doing anodizing, and the anodizing finish chosen on these lights results in a grainy unpolished finish, rather than the much more common smooth finish.

I have a few lights with a grainy finish like this:

  • White Emisar D4 (quite grainy)
  • Blue Emisar D4 (grainy, but not so much as the white)
  • Sunwayman T26C with tan finish (quite grainy)
  • Yellow Fireflies E07 (quite grainy).
  • Olight S10 Ti bead blasted. It’s not grainy anodizing like the others but has that same grainy chalky feel as the other lights.

Overall, I’m not a fan of the grainy finishes. Feels like I’m holding a stick of chalk. The texture just doesn’t feel good in the hands even though it does noticeably increase grip. I’d much rather have smooth anodizing with knurling for increased grip.

I didn’t realize that other brands were using that finish. It does make sense that it would be annodized, especially seeing that the inside of the battery tube is smooth anodize. I’m kind of with you, it looks nice but it’s not nice to feel with dry hands. If my hands are greasy/oily like with lotion or actual grease/oil it feels a lot better, but dry hands it feels chalky. If it is anno over media blast then it seems both together make it chalky.

Cpeng
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djozz wrote:
As others have suggested before, It would be so nice if Hank invested in developing a current regulated driver with the D4 user interface. Instead of making these 219C and SST-20 D4’s just hot and inefficient, they could be run in a much more efficient regime, with not that much lower output. With more and more emitters with extreme low voltages, such regulated driver (perhaps even buck- ) would be an asset for the Emisar brand flashlights.

This would be cool, but isn’t the FET more efficient on turbo then any buck/boost driver because in those all that current would have to pass through the inductor unless there was a bypass. I don’t know why the FET isn’t run in the transistion zone as a voltage controlled resistor which is essentially what the 7135 chip is. Obviously the FET would be using power so it needs to be cooled, and you probably would need a current sense resistor to keep the light regulated. This isn’t the most efficient but it could be more efficient in the 300-2000 lumen range then current PWM. I don’t find myself burning through 18650s like I was burning through single rcr123a and AA lights so maximum efficiency isn’t that important to me as the overall size of the light.

Pavlo
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I would think that FET is most efficient if compared to a different driver pushing current at an equivalent value. Problem with FET is that the LED is running at a very inneficient point on it’s watt to lumen ratio. The other problem with FET is that it’s not regulated so output will steadily drop as battery voltage diminishes.

For those interested in sustained regulated outputs at various levels, buck or boost drivers are able to deliver the constant current and also drive the LED at a much more efficient level. It will also benefit from the low VF LED unlike a linear driver.

If peak output at turn on is your thing, FET makes total sense.

If you want to run the light at a constant 1000 lumen level (heat dissipation and PID aside) buck and boost drivers are fantastic. I love being able to turn on my dqg tiny 7 × 219c at medium or high and know I can rely on a consistent output over a very long duration of time without worrying if my battery is full enough.

I think FET lights are successful in the emisar lights because of the peak lumens and genius pwm programming of the driver.

I think if Hank releases another line not focused on winning the lumen war but on efficiency more similar to Zebralight, he will have another wave of success… Fingers crossed.

Cpeng
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Pavlo wrote:
I would think that FET is most efficient if compared to a different driver pushing current at an equivalent value. Problem with FET is that the LED is running at a very inneficient point on it’s watt to lumen ratio. The other problem with FET is that it’s not regulated so output will steadily drop as battery voltage diminishes.

For those interested in sustained regulated outputs at various levels, buck or boost drivers are able to deliver the constant current and also drive the LED at a much more efficient level. It will also benefit from the low VF LED unlike a linear driver.

If peak output at turn on is your thing, FET makes total sense.

If you want to run the light at a constant 1000 lumen level (heat dissipation and PID aside) buck and boost drivers are fantastic. I love being able to turn on my dqg tiny 7 × 219c at medium or high and know I can rely on a consistent output over a very long duration of time without worrying if my battery is full enough.

I think FET lights are successful in the emisar lights because of the peak lumens and genius pwm programming of the driver.

I think if Hank releases another line not focused on winning the lumen war but on efficiency more similar to Zebralight, he will have another wave of success… Fingers crossed.

A FET can be run as a regulator instead of PWM, that’s basically what is inside a 7135. You could drive the LED at a constant current and therefore the LED would be high eff but theoretical downside is you are burning voltage with the FET. Basically a FET run this way would be the same as infinityx7135 lights.

Pöbel
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The aim of the D4 (and Meteor) was to cram as much power in a comparably tiny package. Buck or Boost with drivers (with similar power) which require an inductor would inevitably increase the total size of the light or require significantly more complex machining (like creating a recess in the Emitter shelf to accommodate the taller components of the driver.

The FET solution is slim, cheap and gets the job done. Yes, there are drawbacks, but each other technology would have drawbacks as well, just different ones.

Pavlo
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Pöbel wrote:
The aim of the D4 (and Meteor) was to cram as much power in a comparably tiny package. Buck or Boost with drivers (with similar power) which require an inductor would inevitably increase the total size of the light or require significantly more complex machining (like creating a recess in the Emitter shelf to accommodate the taller components of the driver.

The FET solution is slim, cheap and gets the job done. Yes, there are drawbacks, but each other technology would have drawbacks as well, just different ones.

I completely agree with you. There will be compromise on both ends.
So now that the more affordable, compact, peak lumen D4 and D4S are available, it would be a great complement if Hank released a slightly longer, more expensive, regulated efficient version with the same emitter options. The driver on a buck boost is indeed larger and more complex, but Hank was able to make the smallest pop can light in the M43 that is still relevant today, so I have no doubt that he can reproduce his magic on a single cell version.

I think thats one of the things that makes Emisar’s so successful, its the fact that you have so many great emitter choices. As far as I am aware, there are no options like that for an efficient regulated light via buck/boost with the exception of the Noctigon Meteor M43 and quite possibly the Zebralights (not quite as customizable as the Emisar in emitter options).

If people are owning multiple Emisars of the same model in different colors and emitter options, I think these same people will also buy a regulated buck/boost version.

The opportunity for Hank is there and I think the demand is as well Smile

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While HWang is taking djozz’s suggestion regarding regulated D4 permutations into consideration, Nichia E21a/Optisolis versions, perhaps even mules could be offered.
A current regulated aspheric D4 with 4+ emitters of the category, and 18350 tube would be tempting.

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I’m hoping that a single emitter D4 (D1/4th?) will be created. I love my D4 with Nichias but it doesn’t get as much pocket time as I thought it would because of the extreme power and the possibility of accidentally turning on. I keep it in a Convoy holster but that keeps it from being an EDC light.

Less power, but still small and having a great UI would be a welcome addition. Maybe with an XHP35 HD or HI?

I also hope that they try to revive their 7 emitter design, but not with a trio of 18650s like they had planned, but with the capability of using a high drain 21700 like the 30T.

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True dat. A single emitter, wide OP/TIR D4 non-hotrod would be a real Convoy S2+ killer.

A Nichia E21A D4 would be glorious.

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I swapped in a Lexel TA 3 channel driver for my D3W1R. With the fet off its regulated around 550 lemons.

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Cpeng wrote:
I don’t know why the FET isn’t run in the transistion zone as a voltage controlled resistor…

Linear FET drivers like that exist. For example, led4power makes some. They’re typically more efficient than a PWM FET driver, and slightly more efficient than a FET+N+1 driver… but less efficient than a boost or buck at most levels. Because instead of burning off extra voltage as heat, a buck driver converts the extra voltage into usable power.

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what is so interesting on sst20 led? if we compare it with xpl…..my another dilema which one to choose:)thanks

EDC- Jetbeam E40R,Emisar D4V2 XPLHI

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The SST-20 has more throw/lumen than the XP-L HI.

In lights like the D4, more throw is useful since you do not need to lessen battery life pushing + power to see far away.

And you can get the SST-20 in 95+CRI, which is nice.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

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thank you very much…bluesword…so now we can mix sst20 and floody optic…is it the best combination what do you think?

EDC- Jetbeam E40R,Emisar D4V2 XPLHI

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PBWilson wrote:
I’m hoping that a single emitter D4 (D1/4th?) will be created. I love my D4 with Nichias but it doesn’t get as much pocket time as I thought it would because of the extreme power and the possibility of accidentally turning on. I keep it in a Convoy holster but that keeps it from being an EDC light.

Less power, but still small and having a great UI would be a welcome addition. Maybe with an XHP35 HD or HI?


I agree.
Cpeng
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ToyKeeper wrote:
Cpeng wrote:
I don’t know why the FET isn’t run in the transistion zone as a voltage controlled resistor…

Linear FET drivers like that exist. For example, led4power makes some. They’re typically more efficient than a PWM FET driver, and slightly more efficient than a FET+N+1 driver… but less efficient than a boost or buck at most levels. Because instead of burning off extra voltage as heat, a buck driver converts the extra voltage into usable power.

At direct drive the FET isn’t burning off any voltage, you really can’t get any more efficient then that (at the same current level) with a buck boost because now you have an inductor in series with the LED in addition to a FET, (unless you have a bypass FET). I would like a buck boost, but peak power is kind of the selling point of an Emisar D4. My use case doesn’t require longer run time and I’ll take my zebra if I do require it. I’m not going to say that its worthless to develop a buck boost D4, and I would probably buy one, but I wonder what I would have to give up in size, brightness, etc.

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The D4 driver is very flat and fits in a very shallow cavity in the D4. A buck/boost driver would certainly add at least 4mm to the length of the D4.

A single emitter D4 would also be longer because of the deeper optic. But there are a few exotic single emitter optics that are very shallow.

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Cpeng wrote:
At direct drive the FET isn’t burning off any voltage, you really can’t get any more efficient then that (at the same current level) with a buck boost …

Yes, but at virtually every other output level, a buck/boost tends to be more efficient. And there’s no reason a buck driver couldn’t also have a FET for turbo. It could use whichever power channel is most appropriate for each level. The main drawback would be an inability to ramp smoothly all the way to turbo. Instead, it would have a gap in the ramp when it switches from the top of the buck circuit to the FET.

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While trying to reassemble my D4 (after flashing Anduril) one of the e-switch solder pads got ripped off the driver Facepalm . Is this repairable or do I need a new driver?

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hodor wrote:
While trying to reassemble my D4 (after flashing Anduril) one of the e-switch solder pads got ripped off the driver Facepalm . Is this repairable or do I need a new driver?

I did this on Lexel TA driver. With advice I hooked up E-switch to pin 2.

I am sure someone in the KNOW can tell you where to hook the E-switch.

Can you tell if its the one to MCU or ground?

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chadvone wrote:
Can you tell if its the one to MCU or ground?

Umm… Closest to pin 2 of the Attiny chip.

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Looking at the photo of the driver in the 1st post of this thread, It sure looks like the switch goes to pin 2 on the MCU. You might be able to see the trace between the pad and the switch pin.

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I can confirm the pad labeled SW+ is connected to pin 2 of the ATTiny85. The other goes to ground, which pin 4 is a convenient point to connect to ground. Or the adjacent pad of the closest resistor R?.

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Thanks chadvone and sbslider, I soldered it to pin 2 and all’s good Big Smile

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good news! Beer

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Cpeng wrote:
At direct drive the FET isn’t burning off any voltage, you really can’t get any more efficient then that (at the same current level) with a buck boost because now you have an inductor in series with the LED in addition to a FET, (unless you have a bypass FET). I would like a buck boost, but peak power is kind of the selling point of an Emisar D4. My use case doesn’t require longer run time and I’ll take my zebra if I do require it. I’m not going to say that its worthless to develop a buck boost D4, and I would probably buy one, but I wonder what I would have to give up in size, brightness, etc.

I’m not an electrical engineer, but I would think eliminating the forward voltage of the FET would provide a significant improvement efficiency. For the D4, I see the number “09NE2LS5” on the FET. From the datasheet I found on that, it looks like it is 0.78V at 30A. This one, like most FETs, shows only minimal improvement in that Vf at lower currents – roughly 0.7V at 4A.

I’ve found the efficiency of the D4 generally fine for my needs though. I wouldn’t view improving further as a high priority.

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iamlucky13 wrote:
Cpeng wrote:
At direct drive the FET isn’t burning off any voltage, you really can’t get any more efficient then that (at the same current level) with a buck boost because now you have an inductor in series with the LED in addition to a FET, (unless you have a bypass FET). I would like a buck boost, but peak power is kind of the selling point of an Emisar D4. My use case doesn’t require longer run time and I’ll take my zebra if I do require it. I’m not going to say that its worthless to develop a buck boost D4, and I would probably buy one, but I wonder what I would have to give up in size, brightness, etc.

I’m not an electrical engineer, but I would think eliminating the forward voltage of the FET would provide a significant improvement efficiency. For the D4, I see the number “09NE2LS5” on the FET. From the datasheet I found on that, it looks like it is 0.78V at 30A. This one, like most FETs, shows only minimal improvement in that Vf at lower currents – roughly 0.7V at 4A.

I’ve found the efficiency of the D4 generally fine for my needs though. I wouldn’t view improving further as a high priority.


Eliminating the forward voltage of the FET would definitely improve the efficiency, but the FET is the controlling element for lower light levels also.

A quick web search showed me a FET with 12milli ohm, 50A rating in the package used on the D4. FETs are like voltage controlled resistors, but once they are “on”, they are a fixed resistance. So 0.012V * 30A is 0.36V, and 0.012*4A is 0.048V. Not sure where the measurements above are measuring, but it seems like there is a fixed resistance in series with the FET being measured which is why the voltage does not change linearly with the current. Or, somehow at lower currents the FET is not being fully turned on at the 4A current. If the measurements include PWM and are being done with a digital volt meter, then all bets are off as to the accuracy of the voltage measurement.

Oh, and I am an electrical engineer, but I don’t get to play that role much these days, more of a project lead now. It’s fun to go back and frolic in the math now and then. Big Smile

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The white “grainy” one got really smooth within a week in my pocket. I could experience this again when I started using the short tube. But after 6 or 8 weeks of use, the D4 is just as smooth as my other lights. Just use and carry them.

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lightboks wrote:
The white “grainy” one got really smooth within a week in my pocket. I could experience this again when I started using the short tube. But after 6 or 8 weeks of use, the D4 is just as smooth as my other lights. Just use and carry them.

For speedier results, pass the light back and forth rapidly on somewhat abrasive cloth covering a cushioned surface.

The edge of a felt covered sofa worked for me when needing to smooth the sharp edges of a Jetbeam TCE-1 purchased new at a third the price. Going Gear sold fifty of the titanium lights at 80 bucks each, purchased cheap from Jetbeam due to complaints about the grabby diamond pattered knurling on the tubes.

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