Kaidomain 50mW CR2 - inital review

[knimrod]

Sounds very interesting, good for a new thread indeed!

Btw, no reply to my support request from KD so far...

I've had very poor experience with KD's customer service.. Here's the email addresses where I've had customer service correspondence with them:

"Dora" <sales@kaidomain.com>
"Kai Lam" <kaidomain@gmail.com>

The last correspondence was regarding my last KD "Edwina" laser that failed in the same fashion as yours except that it it was pretty much DOA when it got here.. Just IR coming from the exit aperture. I wrote to KD and "Kai Lam" responded asking me if I used a 3.6V rechargeable in it. I hadn't at that point and told him so. I never heard back. After a week or so, I decided to try the 3.6V CR2 and it actually lased for a few seconds before gradually dimming out, never to lase again. I then dissected it to find that the LD was kaput.

They did replace my first failed "Edwina" which had to be returned to China before they would send a new one. The replacement still works but it takes a bit to warm up and the beam is occluded by the exit aperture before it's warmed up. It draws an alarming amount of current with a 3.6V CR2 so I only run it with a 3.0V CR2.

 

[IgorT]

I heard about their lousy customer support before.

But i guess at least a few people did manage to return a KD50 or two, because i'm pretty sure i got a used one. It has some problems, which would explain why it was returned, and was glossy from handling and scratched.


DX only accepts returns, if the shipping is less than 30% of the price. With the KD50 that is impossible, which could be the reason. But they are so cheap, that if i should decide to buy more, i could really just use the bad ones as hosts for reds. Need to find an easy way of mounting modules in there.



EDIT: I just got the AMCs, so it's time to start making some drivers.

Oh, and Benm: The NewExcite store seems to have shipped my battery order. They just don't like talking to their customers obviously. They didn't even respond to the PayPal dispute untill i escalated it. Now everything would seem to be ok, so there's nothing to worry about, i think..

 

[Benm]

DX only accepts returns, if the shipping is less than 30% of the price. With the KD50 that is impossible, which could be the reason.

Possible or not, they could at least tell me one way or the other...

So far for coporate communication skills - but at least i hope we get our batteries without further problems.

I installed the "3.0v" in the dx200 red, they seem to work very well there.

As for the KD50, i might as well just order another one. The dead one i could convert into a red, but also into an IR by removing the MCA entirely. In either case i'll have to see if the focussing lens can be screwed in deep enough to allow focussing the diode directly. I'm not entirely sure that i'm comfortable making an IR though, as it seems too dangerous for the fun it'll be.

 

[bob12345]

I would think red is a bit safer. On the other hand the IR diode must only be around 300mW, I don't think that would be much of a problem after a certain distance.

How would we go about converting it into a red in any case? I'm very interested since I purposefully broke the IR LD. I do have an Aixiz module which is proving to be an utter bellend to screw apart.

 

[knimrod]

DX only accepts returns, if the shipping is less than 30% of the price. With the KD50 that is impossible, which could be the reason.

Possible or not, they could at least tell me one way or the other...

So far for coporate communication skills - but at least i hope we get our batteries without further problems.

I installed the "3.0v" in the dx200 red, they seem to work very well there.

As for the KD50, i might as well just order another one. The dead one i could convert into a red, but also into an IR by removing the MCA entirely. In either case i'll have to see if the focussing lens can be screwed in deep enough to allow focussing the diode directly. I'm not entirely sure that i'm comfortable making an IR though, as it seems too dangerous for the fun it'll be.

I could always send you the MCA out of my dead KD 50 and you could possibly resurrect it but I'm betting your LD is dead also.. I thought I might do something with this housing/parts but I'm sure it'll wind up in my junk pile with a bunch of other projects I never found the time to do.. You're welcome to it if you want it..

 

[IgorT]

How would we go about converting it into a red in any case? I'm very interested since I purposefully broke the IR LD. I do have an Aixiz module which is proving to be an utter bellend to screw apart.

I just had an idea about this, tested it, and it works!
It's ridiculously easy to convert it into a red, using an AixiZ module. Mechanically of course. The electronics will be a bigger problem.
I thought "What if the AixiZ module could screw into the top ring?". Guess what, it does.


You unscrew the lower threaded body-connecting ring, and pull the module out, to get the top ring out. Then you unscrew the top ring, take the AixiZ module appart, and screw just the top part of the AixiZ module into the upper ring.

You also have to make the apperture at the top larger, to be able to focus, without taking the laser appart. Then you can just stick the AixiZ module screwed into the KD50 ring into the head, put a tube of the correct diameter and length in after it, and screw in the lower ring to push the tube up and fix everything in place.


The electronics will be a different problem tho. You can not use a 317 with just one battery. You could use an AMC if only the module wasn't making electric contact with the body, but it is. It would require a very low dropout regulator (like the one BlueFusion is selling) or a current regulated buck or SEPIC converter, that has the load negative potential at gnd.

The only way to use an AMC would be to insulate the head from the rest of the body, by using a plastic connecting ring or something like that. But this would also reduce heatsinking. I also had another idea how to use an AMC where the module is touching the body. It would require putting the AMC between the switch and the battery, and also for another wire to go from battery + to the AMC. It wouldn't be a very clean solution tho.



EDIT: There is a possibility to use an LM317, with 1/2AA Li-Ions (14250), if the driver was made to be small enough, to fit in the head. It could be a little tight, but it should be possible. I am currently converting a 1AA flashlight into a laser this way, and it's even shorter.

I ordered 1/2AA and 1/2AAA batteries from AW on CPF Marketplace, to make very small but powerfull lasers with them.

 

[bob12345]

I think there are a lot of possibilities.

I just managed to get that stupid ring out and funnily enough I fully opened the Aixiz module for the first time; both were completely stuck. And yes as you say, they do fit quite well. I have a glass focusing lens for the Aixiz module which works quite nicely in this casing. The driver can be isolated quite easily but it would require doing a Kaidomain and floating everything on the diode legs. You can then simply hot glue everything in place permanently, assuming you got the focus to infinity correct.

I didn't think that ring even unscrewed. Blasted thing, if it slid out my KD 50 would still be alive

 

[IgorT]

The ring fits perfectly, and provides thermal contact, just where it's needed the most.


The problem with the AMC driver is not isolating the driver, but isolating the AixiZ module from the laser body.

The AMC is perfect for green lasers, that use pump diodes with the positive potential at the base of the diode.
With a red you have the negative potential at the base, so you have to turn the battery around. The AMC has to be between the LD negative potential and the battery negative, but both are contacting the body, creating a short circuit, resulting in an LD being directly connected to the battery and burning out.

To be able to use an AMC, you would have to isolate the module from the body, losing all heatsinking. The other possibility is isolating the battery from the body and using wires. This would be much better, but messy. You really don't want to waste the heatsinking this massive body is capable of providing. Isolating just the head from the rest of the body would be a good middle ground tho.

Look at the circuit in the AMC7135 datasheet, to see where the problem is: http://www.micro-bridge.com/data/ADD/AMC7135.pdf


Oh, and about the focus. I think the best thing to do would be to make the apperture at the top larger. Then you could focus from the outside. I don't like using glue to fix stuff in place, if it is possible to do otherwise. Here, all that's missing is a tube with a very thin wall to leave place for a driver in the middle. Then the lower ring would push the upper ring (holding the aixiz module) into the head, resulting in a much cleaner build and good heatsinking.

Using hot glue to fix the driver in the middle of this tube would be necessary, to relieve the stress on the LD, like you said. The tube would have to be fixed on the upper ring somehow tho, so that pulling it out wouldnt rip the diode's legs out. Altho the ring wouldn't get stuck that hard this way, as it wouldn't be completelly at the top.

 

[Benm]

I would really suggest soldering a little spring to the tailcap swich, and inserting the battery the other way around. This way you can keep the thermal contact and if you want, insert the red diode where the pump used to be - provided that you can get a focussing lens in there too.

You can't use the AMC in that setup as it requires the cathode of the diode to be floating voltage, unless you could actually build the AMC driver between the battery and body on the tailcap end (would be possible by making a 'sandwich'/pill construction that goes behind the battery, but not easy.

 

[IgorT]

You can't use the AMC in that setup as it requires the cathode of the diode to be floating voltage, unless you could actually build the AMC driver between the battery and body on the tailcap end (would be possible by making a 'sandwich'/pill construction that goes behind the battery, but not easy.

That's what i meant, when i mentioned putting the driver between the switch and the battery. But it would still require a second connection between the battery +, which would be at the LD and the AMC at the bottom.

I was thinking about a thin laminated self adhesive strip of copper, that could be glued into the body without obstructing the battery, like a wire would.
It would be quite complicated to assure a proper contact with everything, everytime you screw the tailcap on. But it might be worth it.


I've been looking for a solution for a while now, for those tiny flashlight hosts, alto not all have massive enough bodies, so i wouldn't lose much by isolating the module. I found some 1/2AA batteries, but with the 317 i would be completelly wasting one of them. An 14500 with the AMC could last twice as long, but i couldn't go higher than 350mA... I think at least one open can will be running on the smallest batteries tho, just so that i can set the current to 400mA.

 

[Benm]

I was thinking about a thin laminated self adhesive strip of copper, that could be glued into the body without obstructing the battery, like a wire would.

Perhaps something like the film/ribbon cable used in lcd display connections and such would work, if you can obtain any. Also, i think a very thin wire should fit between body and battery, and since it carries very little current you could use the thinnest wire available.

Inserting an aixiz module and isolating that from the body wouldnt be a good approach i think. Electrical isolation usually equates to thermal isolation as well, and even dispite the limited dissipation of the diode it'd still run rather hot like that.

 

[IgorT]

I realize that, that's why i'll use the smallest batteries for the most powerfull one - so that i can squeeze two in there with a 317 driver.

Some of the lights i got are much less massive, than i imagined, but will fit an additionall tube around the module, and the tube will then be isolated. This will be for my current 16x LDs, that will actually be better off that way, than they are now..


Those thin ribbon cables might be a good idea for the KD50 body. But my batteries don't even allow enough place for that. I would end up having to use 14250 batteries just to leave some place on the side, but once there I can just as well use two.


BTW, I think my batteries from UltraFire shop just came. The postman left a slip for a package from HK.
EDIT: Yep, they're here. So i guess the only problem with this shop is lack of communication. I canceled the dispute.

 

[IgorT]

Now that i got the 3.6V CR2s i also tested my KD50s with them.

It would seem, that higher current is not necessarily better. The one that likes being cold actually starts at a lower power, than on a 3V battery and starts dropping faster.
The one, that likes being hot on the other hand, starts higher and climbs faster.

Looks like i'll have to finetune the current for each one of them, before putting in the AMC.



EDIT: I think i just burnt out the crystals in the one that liked being hot. It suddenly dropped from 56 to 10mW. If the diode was dead or damaged it probably wouldn't be able to do 10, so it could be, that the pump can take this power, but the crystals can't.
Maybe that's what happened to yours, Ben? Were you using the 3.6V battery at that moment?

Well, at least i now have the first candidate for realignment. Could actually help a little, since i doubt the entire surface went puff.
I also have the perfect excuse to order another one...

 

[IgorT]

Nope, it's not the crystals, it's the diode.. It dropped in power considerably. I tried realigning it, but it went from 10mW green to zero. I can't even find 1mW of green anymore.

I measured the diode, and it only peaks to 80mW before it starts dropping and getting hot. The crystals are probably just fine. Maybe i should try aligning the used one, and if it doesn't work, take the diode out and put it together with these crystals.


When you two were turning the diode, did you have the power on, to find the brightest spot? Or did you loosen, turn, tighten and power on?

It's hard to find the alignment without turning it on, because the expander makes the crystals look so small, i don't see the diode chip through them. And i don't think removing the expander is a good idea, because it would be hard to get it perfectly centered again.


I killed my best KD50. Damn!

 

[knimrod]

Nope, it's not the crystals, it's the diode.. It dropped in power considerably. I tried realigning it, but it went from 10mW green to zero. I can't even find 1mW of green anymore.

I suspect this will be the common failure mode for these lasers.. It's exactly what happened to two of the three I've had.

 

[IgorT]

I just lost a second KD50 - the used one. I turned the diode a little, and output stayed the same, but then i turned it some more, and the green is gone.

I'm gonna leave everything as it is, and continue tomorrow very carefully. Don't want to rush anything.

I just hope i can revive one from the parts of two. How the hell did you guys manage to turn the diode without losing green? The DX200 was actualy easier than this.


I noticed the crystals are very off-center in these. Much more so, than in the DX assembly. Turning the diode could result in a fatal reflection from the brass. Damn. Trial and error is pretty much out of the question.