Kaidomain 50mW CR2 - inital review

If i can find a metal tube, that would fit onto the module, between the two rings in the head, the heatsinking would be just perfect!

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If you take it apart completely, and you have only the metal components, i guess it would be possible to actually solder the tube to the ring that is part of the casing.

Still, i think the 30 mW CR2 from DX might be a better host for this project, provided things will fit. Take a look at the attached picture - it looks like the diode has proper metal contact to the body all the way. No gap like the KD, but a true fit. I ordered one o these, but havent gotten it so far, so i can confirm connection or dimensions.

KD just added a bunch of new lasers to their selection. Most interesting is a 200mW New Wish Laser that runs from a CR2 battery for $100.

That's interesting.. I wonder how it'll turn out.. If it doesn't mode hop, and behaves like the KD50, but maybe without the contact issues, it could actually be a great laser. I tried running my DX200 from the green 3V CR2 battery, and it drew around 680-730mA, so a CR2 battery is capable of powering a 200mW.

It's cheaper, than the DX200, but i don't like the way it looks. (could probably get used to it tho) They could have kept the same body as with the KD50. Maybe add some mass on the inside. If a 200mW can live in a pen host, it can thrive in the KD50 body. Unfortunatelly, i have too many green lasers at the moment, so i don't have an excuse to buy this thing.. Especially since i just got the CNI150.. I guess i'll wait for reviews.. Could be a great resale candidate tho.. A good alternative to the bad DX200.


EDIT: If the new arrivals at KD are genuine New Wish, and the KD50 is just a copy of New Wish design, the new series of lasers could actually be better. Now that would be impressive.. And the more i look at it, the more i like it. Damn! Must. Resist. Buying. Laser!

Knimrod, did you see the two wires going into the head on the other side of the circuit? This thing could have PD regulation and even an IR filter! Oh my god, what crappy timing. On the other hand, they used one and the same pic for all of them, so it doesn't necesarily mean anything.


EDIT EDIT: Couldn't resist the temptation. Had to buy the 200mW model. My excuse is, that i have a bunch of 3.6V CR2s, but hardly enough lasers to use them in.. :

Need to join laser addicts anonymous. There's something wrong with me.

Benm said:

If you take it apart completely, and you have only the metal components, i guess it would be possible to actually solder the tube to the ring that is part of the casing.

Still, i think the 30 mW CR2 from DX might be a better host for this project, provided things will fit.

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The KD50 looking DX30 could perhaps be a better host for my transplant, but only if the threaded ring (making the good contact with the body) comes off the middle module tube. If it doesn't, or if it's in one piece with the module tube, it would make a transplant impossible. All the pictures so far made me think it's one piece, which is good for the laser, but not for my plans.

On the KD50 you can remove the upper (tension adjust) ring, and the lower (body connecting) ring, and you're left with the module, that is almost identical to the module from the DX200... If you now put the two rings on the DX200 module, you can simply mount it into the KD50 head. Some additional metal (brass tube) in between the two rings will make it just perfect. Soldering the lower ring to the tube is a great idea, and would make it even better.


I will be very interested to hear how the DX version comes appart..

That 200 mW would be great if it performes up to spec - please review it when you get it! I've always found the extenal photosensor setup very odd, but we'll see how it works out.

As for the body style, i don't really like the way it looks either. Making the whole body wider would have been better, and a tad longer would have allowed a CR123 battery with higher capacity and protection. On the bright side, it does look beefy enough to handle the heat, and the connection between diode and body seems all metal.

I will be very interested to hear how the DX version comes appart..

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It's still 'waiting for supplier', so that might take a while. When i get it, i will do some side by side pics with the KD50 to point out similarities and differences.

Benm said:

That 200 mW would be great if it performes up to spec - please review it when you get it! I've always found the extenal photosensor setup very odd, but we'll see how it works out.

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Oh, absolutelly. My other excuse for getting it, is so i could test it, and tell you guys how it preforms.. : I think i have a problem...
Otherwise, this laser is very close to what i intend to achieve with my transplants, so it could actually be really good.


I remember that thread, where you discussed this type of regulation. I think it would actually be interesting, if the laser was truly regulating the green, instead of just the IR. But the pic is probably of a much lower power model, which has smaller temperature variances. A more powerfull model could easily burn the pump, as it would try to compensate for the drop in power.

It's quite likely, that the 200mW model won't have this in which case i won't feel bad about converting it to current regulation.

Seeing how the DX200 preforms, and how it could preform if it had any heatsinking at all, this new New Wish laser could theoretically even outpreform my CNI.

As for the body style, i don't really like the way it looks either. Making the whole body wider would have been better, and a tad longer would have allowed a CR123 battery with higher capacity and protection. On the bright side, it does look beefy enough to handle the heat, and the connection between diode and body seems all metal.

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It would definatelly benefit a lot from a larger battery. On the other hand i have so many CR2s, that i really don't care about the capacity.. I just want to put them to good use.

Otherwise, i was browsing the New Wish site a while ago, and this odd shape would seem to be quite common among their products.. I only found the 5mW model then, but it would seem they just used the same body for this thing. There are one or two examples of this oddity on DX as well.

knimrod said:

KD just added a bunch of new lasers to their selection. Most interesting is a 200mW New Wish Laser that runs from a CR2 battery for $100.

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This seems to suffer from the same problem as the KD50 - the driver is freely suspended and hence pressure will be placed on the diode & its legs:



Now I was going to get the torch style for an extra $35 but this looks enticing.

IgorT said:

I remember that thread, where you discussed this type of regulation. I think it would actually be interesting, if the laser was truly regulating the green, instead of just the IR. But the pic is probably of a much lower power model, which has smaller temperature variances. A more powerfull model could easily burn the pump, as it would try to compensate for the drop in power.

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I guess in good design, this is just a choice: Do you want stable output power, or the maximum that can be achieved given the circumstances. Obiously there should be a limit to how far the current is increased staying within the pump diodes specs.

One problem is that 1 amount of green can equate to two different amounts of pump power: A lower one where the pump is driven well below maximum and things stay at a nice temperature, and a higher one where the pump is driven so hard the thing heats up and the green output drops due to thermal problems. At higher ambient temperatures that can become a problem: the driver notices to little green, ramps up the pump power, heating things even more resulting in reduced output despite the increased pump current.

This effect actually does happen with some of the DX pen lasers: there actually is an optimum current, and when you go over it, green output reduces. For my DX20 the optimum is 300 mA, and it does already dim visibly when i feed it 330.

For these portable pointers i'd say the best strategy is to go for constant current - it's the easiest to achieve and will give you the most green you can get over a reasonable temperature range.

bob1122 said:

This seems to suffer from the same problem as the KD50 - the driver is freely suspended and hence pressure will be placed on the diode & its legs:

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Yeah, well they are all built like this. And it can easily be fixed, so i'm not worried.

Also, this will have a 9mm pump, mounted with a much larger nut, so it won't be affected that badly.. At least the pressure is towards the crystals. Imagine the pen lasers, where you push on the button on this unsupported driver. You bend the PCB down every single time you turn it on. This is what really bothered me with the DX200. I stuck some plastic under the PCB and it was better immediatelly. Here, some hotmelt glue will take care of it permanently. Of course i will replace the driver first. If i'm lucky, maybe even with the SEPIC, which will make the battery last much longer.


Otherwise, i would not want to buy that 150mW thing. It may look like an expensive laser, and cost more, but i trust this one just a little bit more, simply because it is NewWish, and because it reminds me of the KD50 i guess. Everything else looks much better tho. This one will not have any switch and other contact issues.

Benm said:

This effect actually does happen with some of the DX pen lasers: there actually is an optimum current, and when you go over it, green output reduces. For my DX20 the optimum is 300 mA, and it does already dim visibly when i feed it 330.

For these portable pointers i'd say the best strategy is to go for constant current - it's the easiest to achieve and will give you the most green you can get over a reasonable temperature range.

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Very nice explanation Ben!

I did notice just this behaviour a while ago and was thinking about the same thing. In the DX200 i could actually make it better with constant current, that was slightly lower. I could even put off mode hopping for a while this way.. And with the KD50, there are certain higher currents, where the output starts dropping faster. The crystals might already be saturated at that point, so the power increase is hardly worth mentioning, but the extra heat achieves the opposite of the desired effect.

So yes, i think current regulation will be the best option for this and other green lasers. And the AMC makes it a piece of cake.


Can't wait to get this fugly 200mW lazor, so that i can try to get used to it's appearance.. But on the other hand it is better, that it looks like this. At least then, i will be much more happy with my KDX200s...



EDIT: Hey, i just noticed this thing is not brass like the KD50, but alluminum! It's gonna be much lighter, and still have good heatsinking. Interesting.

Also, the first organ donor for the KDX200 project is on it's way! It survived the testing procedure i specified, so i know it will be a good one. Rain had to test six to find one, that would pass.
He said: ok, i got one for you, i have tested six units, then pick out the best one, one minutes, always bright, then 30 seconds through maganify glass, one point, no split. so this time will be ok.

I was beginning to think i would never get a good one. The other one will have to wait for the next shippment from the manufacturer, as they ran out, but he will do the same test for me.

Where/how exactly are you having these dx200's tested and returned if not up to spec?

As for the brass/aluminium thing: On the really long running times this will not matter much as both are good thermal conductors. On the short run, an aluminium one of equal size will heat up a lot faster on account of it being a lot lighter.

Benm said:

Where/how exactly are you having these dx200's tested and returned if not up to spec?

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Well, DX is actually very good when it comes to replacing or refunding broken stuff.
They probably just turn the bad laser on, see that it's bright and sell it to the next person ordering it tho. Unless of course it's really bad.

But when i got the first DX200 and it was modehopping, i filled out a RMA, but said i would not return it, but ordered another one, if they make sure it's a good one. Rain answered, and tried to be very helpfull. We talked over e-mail and in the end i described the testing procedure to him, and even stayed up till three in the morning, so he would be at work, and we could talk over Skype.

He said it was "always bright, no dark" and sent me yet another bad one.  :


After that i tried contacting him, but he wouldn't answer, so i arranged the return of the second one, and started bugging the DX staff at random about the testing i want. I said they don't have to refund me the return shipping, as long as they make sure i get a good one. In the end i decided to return the first one as well, because Rain didn't hold up his end of the deal and didn't answer my emails.

But then he suddenly answered again, said he would keep an eye on my order, and actually went through the improoved testing procedure with the magnifying glass - 1 minute on to observe brightness changes, 10 seconds off, 30 seconds on through a magnifying glass, to make sure there is no mode hopping. I even had to tell him the SKU of the magnifying glass. I figured if the laser could make it through this it should be a good one, as the best i could get from the other two was 30-45 seconds before beam splitting into four from the second one, and as little as 5-10 seconds from the first one. After they were warm, they would both do it instantly, which is why i made the test in two parts.


Today i asked him if he had PayPal, so that i could reward him, but that i would make the reward larger, if he could test the other one as well. He said yes, and now i'm waiting for the next batch of DX200s to arrive from the manufacturer. He also promised to ask who the manufacturer really is.

BTW, what would be a good reward for someone from Hong Kong?!? I really don't know what standards they have.

As for the brass/aluminium thing: On the really long running times this will not matter much as both are good thermal conductors. On the short run, an aluminium one of equal size will heat up a lot faster on account of it being a lot lighter.

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I was wondering it mass of metal has an influence on the amount of heat it can absorb.

I guess if a heatsink has fins and a fan on top, alluminum can do just as well, but here.. We shall see.. Besides, i want my KDX200s to be the best anyway..


One question.. If more mass is better for quick heatsinking, do you think i could use lead, since it would be very easy to form into a custom shaped heatsink, that would fit into a flashlight head together with a peltier? I guess it wouldn't hurt to try...

You want highest specific heat capacity and conductivity, bottom line. Lucky for us, these two properties are intricately linked. More mass is not necessarily a good thing (although more density can be). Basically, you're free to choose whatever as long as it maximises those two properties. Copper seems to be ideal - second highest thermal conductivity of available materials. Unless you're filthy rich and you can afford a pure silver heatsink (or equally, an RPL-400).

Lead, not so good - see this table: http://www.engineersedge.com/properties_of_metals.htm

I do have some "pure" silver (100g of 99.99%) in my drawer, that i bought a while ago for a project i later abandoned.

Perhaps i could hammer it into a the heatsink shape i need.. Thank you for reminding me.. Too bad i'm not fithy rich as well, but 100g should be enough for more than one heatsink.


I could even have it poured into the exact shape i need, but that would cost more, than the material did.

Nice to hear that the people at DX are doing their best to get you something good...
i think a reasonable tip shoud be around 1/3rd what you would give someone in the US or western europe for equal services - considering the cost of living in a place like HK.

As for the metals: Lead is very dense but has very poor thermal conductivity. Silver is good on both, but not that much better compared to copper. As a material for casings copper is usually superior to aluminium in terms of both electrical and thermal conductivity: Pure aluminium is very good, but most casings are made of aluminium alloys that often have far worse specs. Using alloys has major benefits for mechanical properties, but they should not be considered to be pure aluminium when looking at thermal or even electrical properties.

Machining is even more important though: 1 mm of air gap is as bad as a whole meter of copper between two components - and that applies to a micrometer of air and 1 mm of metal as well!

Perfect thermal contact is essential. I used to make my own heatsinks for "sub-"micro helicopter motors (nothing suitable available), and if i didn't shape it perfectly, only the heatsink would remain cool.. Of course the rotor does all the heat dissipation there.


About returns to DX..

Rain told me, they are doing very good business with these lasers, while someone who bought 5 said 3 of them were mode hopping. Looks like most people who buy them simply don't notice this, or don't even know what it is.  A couple of others don't bother returning, or think it would be too much fuss. So it's probably not that many people, who complain.

As long as you follow all the instructions, returns are easy. They even refund the return shipping (I ordered a tripod and a Cree LED for the shipping on one of the two, nothing on the other). You just have to explain the problem in a simple language, take some pictures, and use registered shipping once you have an RMA. You also have to include a short note in the package, stating what the problems are, the order number, SKU and so on. This is probably important for HK customs, as well as for DX, so they know who it's from and what it's about.

After that you need to upload a photo of the post office receipt to a hosting site, give them the link and explain how to track. I also include a photo of the envelope with the contents around it, and another of the envelope after sealing it.


Most people who are complaining about their lousy support must have done something wrong, because so far i always got an answer immediatelly, they were all very friendly and helpfull and i am very satisfied with the service so far.


For selling stuff this cheap, all this really is an amazing service. If i wanted to return my CNI laser, i would probably have to pay EMS shipping both ways plus chinese bank charges for transfering the shipping cost to them, in the worst case scenario.. This would cost as much as the laser did. It's driving me crazy. Need to talk to them on monday.. I wonder what they'll say.

The problem is, that it peaks at up to 178mW, remains above 170 for 20 seconds, above 160 for another 10, but then it suddenly drops to 130 and remains there for the remainder of the minute. This is if i cool it down first. If it's at ambient, all this happens a little faster. The mathematical average is still around 150, or slightly below, but i guess i expected more from it.

It would seem, that these cheap New Wish or no-name lasers are not really all that bad after all. It would also seem, that CNI sends all the best ones to Nova, which means that those really are worth the extra money..