New DX Green MODULES

disma · Aug 23, 2009

I also ordered one of these, seeing how bad everyone else's was doing, I turned down the pot on mine to a current draw of 450ma... It still works, and has about 10 min on it, I wonder what the diode is rated at? I don't think its even a 500mw diode, more like 350 or so, but I could be wrong. :undecided: And this is supposed to be 200mw! Maybe 200mw input power? I started out at 2.2v on my lab power supply and raised the voltage untill I saw the current exceed 600ma! The pot on the board was cranked all the way up before I changed it. After I adjusted the pot, I tried turning the voltage up some more and the board started to get really hot at about 3.3v, I was trying to get it up enough to put the module into an 18650 host, so unless you add some voltage drop diodes or some other voltage limiting part in series with the 18650, it wouldnt be safe to do this.

seoguy · Aug 24, 2009

To fix the alignment issue I removed the expander lens/OC and glued it down so that the beam was more centered with the collimator lens. After I accomplished this the beam still exited the aperture at a large angle (est. 20-25 degrees from center). This makes me think that the crystals are not aligned properly, throwing off the whole optical assembly.

When I saw that the crystal holder was held "above" the surface of the module, simply sitting atop globs of glue (rather than something more accurate like a spacer), I had wondered how they managed to align it correctly. It seems like perhaps they don't!

Alignment of the lenses definitely has an effect on power.

That's good to know - Thanks! :yh:

I did not adjust the pot....

I only had it running for 5-10 seconds at a time...

I put the module in a brass heatsink for additional cooling.

OK, that eliminates several possible causes...

When my module died I was testing the alignment...

That got me to wondering. Given that the crystal holder is metal, and the diode is open-can, and it would be VERY easy to brush the back side of the crystal holder against the diode innards...
could you have accidentally killed the diode from ESD while trying to re-position the crystal holder?

Normally with dead greenies I get the "dim red glow."

...or perhaps accidentally bumped and damaged the partially mirrored end of the diode, turning a dim-looking high-power IR laser into an invisible low-power IR LED?

Did it die while it was running? Or did it just no longer work after the last crystal alignment was made?

It's possible that the driver does not regulate voltage very well and the over-voltage killed the diode...

I get zero output from the diode. This means either the driver is malfunctioning or the diode is really cooked.

disma's post seems to indicate driver failure as a good possibility. He also indicated the driver itself got very hot at 3.3V, and you were running at 3.4?

I just checked, and that output transistor does NOT have any heat sinking attached to it at all :undecided: (not even a large copper pad on the PCB where the tab connects - just a tiny cold solder joint!)

These pump devices pull a lot of current - I wonder if the driver itself just over-heated and died?

It's possible that the driver does not regulate voltage very well and the over-voltage killed the diode. If this is the case, these may not be able to be run on rechargeable lithium battery types at all without significant risk to the diode.

I have also read of some complete greenies that cannot be safely powered with rechargeables for that very reason.

If true, couldn't we use a suitable diode in series with a rechargeable battery to act as a "voltage drop", to bring it in line with what the driver wants? (Similar to how a diode can be used with a Flex Drive if the battery is a bit higher than 5.5V)

I can't test the driver at the moment as I have no dummy load (lost) and I also lost my good multimeter. Yeah... I know...

Has a LPM, but no DVM? We must live in alternative universes! LOL

I suspect the diode is either 1W and being driven at around 800mW or 500mW and being over-driven to well beyond it's rated limits.

Agreed. The first option would be safer, but not very cost-effective. Given this is a Chinese product, I fear the later option may actually be the case! :undecided:

BTW, I finally received my True 5 from them, and am in the process of writing a detailed review. There is one thing I discovered, however, that is very relevant to this conversation...

Peering down the aperture hole at high magnification, I could see the aperture piece was "THREADED" inside where it meets the end of the module. I could also see down to the lens, which was at the top of the module, was larger, and the lens nut had those two shallow dimples...

From what I could see, it appears that the module they are selling us may be the same design they are now using in their current pen lasers!

I reported visible manufacturing defects with TWO of the screw-apart pieces that make-up my module.

You have also now indicated the SAME THING - TWO faulty pieces (defective lens alignment in middle piece PLUS defective crystal alignment in base).

Almost like somebody selected two bad pieces, and screwed them together?

Given all of this, begs the question...

Is DX simply selling us the manufacturing rejects from its pen line as new modules?

seoguy · Aug 24, 2009

disma, how were you measuring current - at the diode? Or somewhere else?

I don't think its even a 500mw diode, more like 350 or so, but I could be wrong.

DPSS lasers are terribly inefficient. The crystals these appear to be using require 500mw of 808nm in, just to get 100mw of 532nm out. To get to the power levels required for the 200mw units, we're figuring at least 750-800mw of IR, which would be over-driving even a 500mw diode!

Things might be different for one of the lower-power units, of course.

Which model did you get?

untill I saw the current exceed 600ma!

From what I've been able to find on diodes in this range, that's about the right operating current for many 808nm 500mw LD's. Remember, laser diodes are not 100% efficient devices, much of the power they consume gets converted into heat (hence the need for heat sinking!

)

For example, see the specs on this one from snoctony on eBay (operating current <= 650mA) -

500mw 808nm laser diode TO-5 Package - eBay (item 140339764137 end time Sep-13-09 06:56:42 PDT)

or this one, from a vendor (operating current 600mA typical, 700mA max) -

808nm 500mW Laser Diode

How far above 600 was it?

Were you feeding it 3V at that point, or less?

Did it look like the current increased when you applied more than 3V?

The readings you got (before you changed the pot) can tell us a lot about what they are driving these things at!

I turned down the pot on mine to a current draw of 450ma...

It looks like these type of diodes may typically have a threshold of ~150-200mA, so that should work. You're just going to get significantly less green coming out.

After I adjusted the pot, I tried turning the voltage up some more and the board started to get really hot at about 3.3v

Hmm, interesting! Did this happen before you changed the pot as well? Did you happen to notice which part on it that was getting hot?

I was trying to get it up enough to put the module into an 18650 host, so unless you add some voltage drop diodes or some other voltage limiting part in series with the 18650, it wouldnt be safe to do this.

Assuming it was doing the same at factory settings, I think you are right about that. In fact, from what you have said, I am wondering if RA_pierce actually over-powered his diode, or perhaps just over-heated & killed his driver instead?

The pot on the board was cranked all the way up before I changed it.

That is VERY troubling! That big resistor is only 0.33 ohms, that could feed a LOT of current if running full-bore!

You also wouldn't want to design a driver that way - you want to be able to have some "play" either way, in order to be able to adjust it, to compensate for component differences on each laser!

This may be an indication that DX is pushing that driver / module farther than what it was designed to do? :undecided:

disma · Aug 24, 2009

I was measuring current in series with the unit, I read it from my bench supply, which isn't all that accurate, but its within 25mA or so. When I first connected it to test it to see if it worked or not, It was set at 2.8v, something on the module burned me before I knew what it was, I cut off the power because of this. Thats when I turned down the pot, it shouldn't get so hot it burns you in less than a second! I dont know exactly how far above 600 it was, it was significantly higher though, close to 700ma. IMO thats too much for a 500mw diode... The snoctony diode's are quite efficient, I have 4 of them, and they all prety much do 100mw per 100ma. I measure 1w at 1000ma on both the 1w and the 2w to3 diodes I have, so by this reasoning, the 500mw shouldn't be more than 600ma. I wouldn't run this module at anything over 3.00 volts, It's not able to handle it. I knew it was pushed way too far after seeing the pot was all the way up. This was supposed to be a 200mw module, I seriously doubt that. Maybe it was able to origionaly do 50mw. :yabbmad: Anyway, it was kinda worth 40 bucks, not really though since I could have got a better one somewhere else.

seoguy · Aug 25, 2009

Thanks for the useful data, disma! :yh:

It was set at 2.8v, something on the module burned me before I knew what it was...I dont know exactly how far above 600 it was, it was significantly higher though, close to 700ma.

You weren't even up to 3V yet, and it was already drawing close to 700ma?! :undecided:

IMO thats too much for a 500mw diode...the 500mw shouldn't be more than 600ma

You are absolutely correct! Unless this is a 1W diode, they are severely over-driving it!

This was supposed to be a 200mw module, I seriously doubt that.

Agreed. RA_pierce was able to get 154mw out, but it sounds now like that it was being severely over-driven to accomplish that! Not sure if his died from being driven too hard, or from other issues (ESD/diode die damage) during his crystal re-alignment - still waiting to here back from him on that.

Maybe it was able to origionaly do 50mw.

From what I can tell, if that's a 500mw diode, and the crystals it is using, it sounds like it was probably designed to do 100mw. Unless that's a 1W diode, any more than that would likely require over-driving the laser diode!

BTW, I suspect you can probably adjust yours to ~550-600ma, that should be about right for a 500mw, I think, and get you perhaps 70-100mw of green out, depending on how well the crystals are lined-up?

But any more than that, and you will be pushing it, I think!

And or course, only at 3V - nothing higher without drop-down diodes!

:yabbmad: Anyway, it was kinda worth 40 bucks, not really though since I could have got a better one somewhere else.

Hey, don't feel too bad - mine, the lens doesn't even line-up right!

I finally got my new True 5 pen, and it looks like DX may be using the same type of module inside. I'm trying to disassemble it to find out for sure. But like I mentioned in a previous post, I am beginning to suspect that DX may be taking the manufacturing rejects from their pen line and selling them to us as modules? :tsk:

If so, we need to call them on it! :gun:

Anyway, thanks again for your help! :yh:

BTW, charliebruce reported on the DealExtreme site that he received his, and that it was working well! He also said he was running it off of a 18650

, but only for 30 seconds. Hopefully he will stop by here shortly and give us the details!

RA_pierce, did you see my latest post to you? (#82)

daguin, styropyro, roddenberry, Dark, billg519, laserpyro, Hemlock_Mike, did you get yours and/or have a chance to test it yet?

roddenberry · Aug 26, 2009

seoguy said:
roddenberry, (...) did you get yours and/or have a chance to test it yet?

I did receive the package this morning (I got a postal pickup slip and have to get it at the mail counter this evening). I'll keep you posted on what's in the bag. Thanks for the tip, i'll try the modules with 2 fresh AA battery and 1N4004 in series to keep the juice at a reasonable level below 3v.

Carbon Tetrachloride??? Isn't using that stuff slightly hazardous to your health? Be careful!

Yup. I only use that stuff with very tenacious gunk, and only sparingly in well-ventilated areas. I know it's awfully toxic... I was surprised to see that 15-20 years ago, pure CCl4 was used as shoe polish remover and came in little glass bottles with a cotton ball applicator!!! But I'd rather use CCl4 than highly toxic and carcinogenic 1,1,1 trichlorethane which was commonly used when I used to work at Xerox. I tried to avoid using that stuff at the time. I still have a can of that stuff in my lab. :undecided:

But back to the greenies... I'll try to fiddle with these tonight but I doubt i'll even have time to because I'm finishing up a graphics work that needs to go to the printer on Friday. Anyway, when 11 PM comes around, I'm as productive as a doorstop.

Robert

billg519 · Aug 26, 2009

Glad to see a few people get these ... I ordered on Aug. 1st, still "pending", maybe by Christmas.

Didn't they use CCl4 in drycleaning years ago?

roddenberry · Aug 26, 2009

Okay so I went to the post office and retreived my paxckage. Really overworked and don't have much time to fiddle with this, but I couldn't resist opening and taking inventory. All three modules were individually wrapped in red bubble wrap. The rest of the stuff was loose in the bag.

My initial inspection shows that the modules are slightly flimsy, the driver board is not secured at all, just loose (only thing that holds it is the soldered diode pins) and the brass sections are screwed a bit loose too. Hooked-up a 3v battery on one of the modules and the thing shines brightly. Good sign.

Mhhh. Enough for now. i'll investigate further over the weekend.

Robert

yobresal · Aug 28, 2009

I received 3 more today. Awesome!!!! They all are very bright and can burn. 2 of the 3 are between 70-125mW the other is around 60. These are rough estimates I will have exact measurement tomorrow but as of now my feelings on these modules has taken a full 180. Also I would like to mention that I find it to be a benefit that the driver is not epoxied to the module like many others. It makes it much easier to remove and relocate as needed for confined builds ie pocket laser show. (spirograph)

daguin · Aug 28, 2009

I got home last night and did a quick check of my "200mW" module.

It is putting out 60mW @ 3V.

It did 130mW @ 4.5V. but apparently I am lucky it is still alive, eh?

Peace,
dave

yobresal · Aug 28, 2009

130mW isn't so bad. I'd actually consider that pretty good. I have been testing mine at 3.8V.

daguin · Aug 28, 2009

yobresal said:
130mW isn't so bad. I'd actually consider that pretty good. I have been testing mine at 3.8V.

For the price I am NOT terribly disappointed.

Yeah, but will it live at 4.5V?

Peace,
dave

nikokapo · Aug 28, 2009

daguin said:
For the price I am NOT terribly disappointed.

Yeah, but will it live at 4.5V?

Peace,
dave

I don't know, the other guys presenced their diodes' deaths too soon... did you get a freak one again

?

daguin · Aug 28, 2009

nikokapo said:
I don't know, the other guys presenced their diodes' deaths too soon... did you get a freak one again ?

I think that it is all of the rocks around me

Heck! For $40 I'm willing to push it with 4.5V. I can still use the Kryton with a diode

Peace,
dave

yobresal · Aug 28, 2009

I will try 4.2V when I get home from work. I will also have exact power measurements.

yobresal · Aug 29, 2009

4v works fine. That big resistor gets hot as he'll. I tested them but now I am away from my filter ir. Tomorrow.

New DX Green MODULES

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