My Emisar D4 is a “touch” light?

ZED · 2018-12-20T04:06:05.000Z

I put a link a few posts up. I put a video on my YouTube channel. If you watch you can see how the pressure of my hand (surface area of my hand on the light) affects the light output. Still it’s all less than a lumen I would say almost certainly.

ZED · 2018-12-20T04:09:05.000Z

And I have to say, normally something like this would bug me like a speck of dust in my reflector—which btw using your tongue really is the best method for cleaning one—it’s actually kind of cool as long as it’s safe. I guess time will tell if it’s safe.

moderator007 · 2018-12-20T04:21:24.000Z

I kind of think there is something touch in the tail cap. And it maybe very small with no more light than its making.
When you stuck your finger on the battery and the tube should be the same as you holding the cap and touch the head.
I just pulled my D4 out to look this over, the tail is always connected.

moderator007 · 2018-12-20T04:24:37.000Z

I’m trying to figure this one out but that’s just strange it acts that way.
Maybe you are just are a good conductor. Too much salt .

Lexel · 2018-12-20T04:27:37.000Z

I have seen this issue before

The only explanation I can give is that the LED- on MCPCB has a grounding or low resiastance(conductive acid flux) to the head part, easily to check with DMM
But the D4S has insulated driver and Tube usually, so there cant be a current flow bypassing the driver
seen on Lights like Convoy L6 going instantly to Turbo when you turn on on Tail switch

so you act as cinductor between head and Tube bypassing the driver

ZED · 2018-12-20T04:27:49.000Z

Yeah but think about it. When the batter is in and the cap tightened, the flashlight is energized ready to go. When it’s slightly unscrewed it isn’t, even if the threads were bare aluminum, the negative part of the battery is touching the spring and pcb it’s connected to, nothing else. So it needs to be energized, i.e. have potential, for this to work. I mean I don’t think there’s really anything in the tail spring to go wrong or act anomalously. I don’t know but it’s really freaky doing the two person thing and lighting it up upon touching someone else’s hand.

chadvone · 2018-12-20T04:28:38.000Z

just watched the video. You should sell that broken D4 to me…

Lexel · 2018-12-20T04:30:22.000Z

ZED:

Yeah but think about it. When the batter is in and the cap tightened, the flashlight is energized ready to go. When it’s slightly unscrewed it isn’t, even if the threads were bare aluminum, the negative part of the battery is touching the spring and pcb it’s connected to, nothing else. So it needs to be energized, i.e. have potential, for this to work. I mean I don’t think there’s really anything in the tail spring to go wrong or act anomalously. I don’t know but it’s really freaky doing the two person thing and lighting it up upon touching someone else’s hand.

read my post and think about it
even with unscrewed tail cap you touching the bare battery bottom it will light up

ZED · 2018-12-20T04:35:26.000Z

Sorry lexel I was respondeing to moderator007. That makes sense and without the knowledge of specifics is kind of what I was thinking. I bet you my ground (black) wire is touching the MCPCB. cause for alarm or is it fine?

Lexel · 2018-12-20T04:38:12.000Z

ZED:

Sorry lexel I was respondeing to moderator007. That makes sense and without the knowledge of specifics is kind of what I was thinking. I bet you my ground (black) wire is touching the MCPCB. cause for alarm or is it fine?

if its a dead short with worn anodisation on threrad it leads to DD turbo light if tail cap gets twisted on
if its just some conductive residue light will constantly light up at a low level

moderator007 · 2018-12-20T04:40:13.000Z

It looks like you have had this light for awhile. Did you recently mod anything or take it apart?

everydaysurvivalgear · 2018-12-20T04:45:00.000Z

Looks fairly normal to me the part of the bezel you are touching has no anodizing left on it? So you have current leaking into the MCPCB from some where.

NWoodsman · 2018-12-20T04:59:24.000Z

I swear this just came up elsewhere. The FET has no bottom limit on the voltage it senses. It acts like a gate, and the human body voltage is opening the FET allowing a high enough voltage to leak off the battery and glow the emitters.

Lexel · 2018-12-20T04:55:06.000Z

NWoodsman:

I swear this just came up elsewhere. The FET has no bottom limit on the voltage it senses. It acts like a gate, and the human body voltage is opening the FET allowing a higher voltage to leak off the battery.

wrong the FETs gate is grounded with 100k and the MCU pin at ground too so there is no way you can activate the FET in any way

chadvone · 2018-12-20T04:59:45.000Z

Lexel:

so you act as cinductor between head and Tube bypassing the driver

I didn’t think the head threads of the D4 were anodized, but I just looked and they are on mine. I tried to duplicate this with a led some wire and and a 18650. I couldn’t get any light no matter the combination I held them in other then just wiring it up.

I would guess there is some power bleeding through the driver/head contact. But that is just a guess.

Lexel · 2018-12-20T05:15:06.000Z

chadvone:

Lexel:

so you act as cinductor between head and Tube bypassing the driver

I didn’t think the head threads of the D4 were anodized, but I just looked and they are on mine. I tried to duplicate this with a led some wire and and a 18650. I couldn’t get any light no matter the combination I held them in other then just wiring it up.

I would guess there is some power bleeding through the driver/head contact. But that is just a guess.

the conductive connection does not need to be on the MCPCB can be on driver as well

I thimnk there are different versions of D4 lights very old had blank machined MCPCB shelf while others were anodized

NWoodsman · 2018-12-20T05:32:36.000Z

I still rule out ground short. The wear in the anodization is the clue, his body is essentially a battery and his touching the head and tail means he is applying a reverse voltage to the deanodized ground which is backtracking across something. If not the FET than maybe directly across the emitters. Do you live in an extra dry place with static electricity? A 4000v static charge can overcome a 100k resistor.

Edit to add: the more surface area he grips the light with, the brighter it gets. Something is turning his body’s milivolts into a nice smooth boost up to at least around 2.3v.

Lexel · 2018-12-20T05:32:21.000Z

NWoodsman:

I still rule out ground short. The wear in the anodization is the clue, his body is essentially a battery and his touching the head and tail means he is applying a reverse voltage to the deanodized ground which is backtracking across something. If not the FET than maybe directly across the emitters. Do you live in an extra dry place with static electricity? A 4000v static charge can overcome a 100k resistor.

there is no way you overcome the MCU dead ground to FET gate and its totally insulated from the body, I mean there are ate least 2mm space between the driver rim and those resistors and heads driver rim is anodized
the LED- has connection to the head part of the flashlight which is insulated from driver and tube, touching now tube and head makes a connection,
touching tube and head with a copper wiore may lead to turbo if there is really a short between LED- and head

NWoodsman · 2018-12-20T05:57:02.000Z

In the video, he grips the tail and lightly taps the rim of the bezel. His one hand is not directly touching head and tube. There is no way he is completing the li-ion circuit across his torso from one hand to another enough to put 2v across the LEDs.

That doesn’t change the fact that his gentle touch is somehow causing 2v to appear from nowhere.

EDIT: Ok nevermind. My new theory is that he is in a room with a lot of RF signal. His body is acting like a crystal radio and attenuating the atmospheric voltage straight across the leds.

g_damian · 2018-12-20T07:51:54.000Z

What if during reflow led negative was shorted to the MCPCB?

That could explain why touching tail (negative) and head bypasses the driver and turns on leds.