MXDL Over 300mW! (LPM Reading Video pg. 2)

I know, sounds like 'this guy must be talking mA, not mW'. Let me tell you first that I have settled on 294mA, using the DDL driver with a 4.3 ohm resistor at the LM317 as being the 'sweet spot' for the MXDL and the Senkat diode...that is, if you have a good heatsink in there as well. This combination puts out over 200mW.

Now, since Gazoo has been having good results with his AMC7135 driver and the open can diode, I decided to try the 7135 driver in an MXDL. This involved drilling out the body of the MXDL on my lathe using a 3/4" drill bit so that it would fit an 18650 battery to run the AMC7135/350mA driver. Once again, at this current, we're talking about the open can diode that Gazoo showed me. (harvested from a Pioneer 112D DVD)

The result surprised me!!! For some reason, this batt/driver combination with the open can diode is putting out over 300mW!
I thought something was wrong because I had the same MXDL/open can running at 324mA using a DDL driver and 3.6 volt batteries x 2 - putting out only 194.5mW. (This is in harmony with Hemlock Mike's graph and I figured it's normal) Yes, fresh charged batteries and I checked the current.

All I did, was change the driver and battery. I want to tell you that I got the (how to) wiring diagram of the 7135 driver ahead of time and followed it correctly. I also checked the current before I connected the diode. I got a reading of less than 350mA and was disappointed...it was 338mA.

But when I connected the open can diode and measured the power with the LPM-1, I got a reading of 314mW peak and it stayed over 300mW! Naturally, I turned it off after about 15 seconds and started double checking everything.
First I checked the setting of the LPM and measured a known red laser as well. Then I took the MXDL apart and measured the current at the diode and got a reading of 338mA. Then I tested the power again with the LPM and got the same 300 plus readings!
At this point, it really doesn't make sense to me that this driver at 338mA can be running the open can at over 300mW. Especially when the other driver at 324mA was only getting it to 194mW?? Everything is the same except the driver and battery. As you can see from the picture, I didn't even mess with the LD. I left the silicon diode and the cap right there and just soldered the wires together with the wire leads that I put on the AMC7135 driver...
Scratching my head...but very happy!
Jay

Edit: Although this project starts out with a single 18650 battery. Later in the thread, I re-designed and went back to a custom DDL driver with 2 x 3.6 RCR123s and a different module as well. The result is an MXDL that puts out over 300mW! Read on and see how...

(nice match burn video on pg. 4 as well)

Re: MXDL Over 300mW!

Ok...I did find another variable that must be causing the difference. I checked the voltage to the LD and got a reading of 3.55 volts for the AMC7135. This is with a single 3.7 volt 18650 battery. With this combination, the open can diode is putting out over 300mW. (AixiZ acrylic lens)

This MXDL (30 minutes before) was running the open can with a DDL driver at 2.98 volts and 324mA. Using 3.6 volt batteries x 2. With this combination, the open can diode was putting out 194mW.

The other comparison I have is my Ice Box laser. It is currently running an open can diode from the same model (Pioneer 112D) DVD. The driver is a DDL driver which is set to 416mA. The other difference (besides current) is, the voltage reading at the LD is 2.98 volts. This is using a 7.4 volt lipo battery pack. With this combination, the open can diode is putting out 287mW (measured with a glass lens) . It's power was less with an AixiZ acrylic lens...247mW.

Anybody know if 3.55 volts to an open can DVD diode is ok? I know that even with the heatsink, this will be used with a short duty cycle. Just wondering about the voltage...

Gazoo, you have been using this AMC7135 driver...I can only think that the difference in power, is the voltage...
Jay

Re: MXDL Over 300mW!

you are nuts... i think the diodes will just die from catastrophic semicontuctor damage ( just plain power not heat)

Re: MXDL Over 300mW!

jayrob said:

Anybody know if 3.55 volts to an open can DVD diode is ok? I know that even with the heatsink, this will be used with a short duty cycle. Just wondering about the voltage...

Click to expand...

If the desired current results in that voltage, it should be fine. I'd think it is a bit on the high side, but U/I curves for laser diodes vary between samples.

In terms of COD you probably have a pretty good diode there, i'd expect most to quickly die from putting out that much light. I wouldn't push this diode any further, just keep it running somewhat below this power level... chances are you won't find one like it once you've blown it up

Re: MXDL Over 300mW!

check ur PMs jay

Re: MXDL Over 300mW!

is that the DX AMC7135 board with only one 7135? For the power you're getting out of it it sounds like you're running it at closer to 700mA not 350mA. Also, did you have your ND filter in front of the power meter?

Re: MXDL Over 300mW!

I thought the MXDL ran on 2 CR123's, hence the 6v MXDL... why the need for an 18650?

also, where did u get that heatsink from?

Re: MXDL Over 300mW!

amkdeath said:

I thought the MXDL ran on 2 CR123's, hence the 6v MXDL... why the need for an 18650?

also, where did u get that heatsink from?

Click to expand...

Because 6 volts is too much for this regulator. Did you read my review of it???...

http://www.laserpointerforums.com/forums/YaBB.pl?num=1191898669/0

Re: MXDL Over 300mW!

I'm very interested...but that sort of power seems strange!!!!!

More info please!!!!!!

Larry

Re: MXDL Over 300mW!

Jay,
I am scratching my head too trying to figure this out. One thing I would do is remove the silicon diode you have soldered to the laser diode and see if anything changes. It could be it is adding to the voltage drop of the laser diode and would explain the high voltage reading. Remember the 7135 is a totally different animal than the 317. I did measure the voltage going to my diode and it is exactly 2.8 volts.

But it would not explain how you are getting 300mw's out of a diode running with only 338ma's. I am totally baffled by that. Even if the regulator was putting out the full power the most you should see is around 255mw's using a glass lens. I am sure you slid the ND filter in front of the meter, and you have your meter set on the 660ND setting? From your previous measurements I am sure you do, so this doesn't make sense.

I don't recall how much current is going into my open can with this regulator, and I would have to de-solder my peltier to check. But I am using a 7135 to power a SenKat diode and it reads exactly 350ma's. Of course I have a 33 ohm resistor in parallel with the diode, so the diode is only seeing ~250ma's.

Re: MXDL Over 300mW!

Oh man...the wheels are turning!

Re: MXDL Over 300mW!

dood, leave it as is!! dont mess araound with it, u might kill it, and u may never get a laser at that power with that much input ever again!!

WHat heatsink are you using and where did u get it from?!?!?


I didnt know that 6v is too much for this circuit, that sux... I jsut bought one... so ur saying I shud drill out the tube with 3/4" drill bit and use 18650's?

thanks.

amk

Re: MXDL Over 300mW!

a_pyro_is said:

is that the DX AMC7135 board with only one 7135? For the power you're getting out of it it sounds like you're running it at closer to 700mA not 350mA. Also, did you have your ND filter in front of the power meter?

Click to expand...

Matt, yes that is the 350mA 7135. I made sure to check the readings on other lasers as well...settings are correct (660/ND), filter in place.

I thought the MXDL ran on 2 CR123's, hence the 6v MXDL... why the need for an 18650?

also, where did u get that heatsink from?

Click to expand...

amk, This MXDL has been modified by drilling out the body with a 3/4" bit, so that it fits a single 18650. The heatsink is custom machined to fit the MXDL...

I'm very interested...but that sort of power seems strange!!!!!

More info please!!!!!!

Larry

Click to expand...

Larry, yes indeed this is very strange. I have double and triple checked my measurements. The exact same diode, 30 minutes before I made the change, was running at 324mA and putting out 294.5mW (-Edit- I meant to type 194.5mW, not 294.5) with a DDL driver, which is normal. Then, I traded only the driver and the battery. The result is 314mW at 338mA?? Not normal... The one difference besides the small difference in current that I measured, is the voltage to the LD. 2.98 volts vs 3.55 with the AMC7135.

Jay,
I am scratching my head too trying to figure this out. One thing I would do is remove the silicon diode you have soldered to the laser diode and see if anything changes. It could be it is adding to the voltage drop of the laser diode and would explain the high voltage reading. Remember the 7135 is a totally different animal than the 317. I did measure the voltage going to my diode and it is exactly 2.8 volts.  

But it would not explain how you are getting 300mw's out of a diode running with only 338ma's. I am totally baffled by that. Even if the regulator was putting out the full power the most you should see is around 255mw's using a glass lens. I am sure you slid the ND filter in front of the meter, and you have your meter set on the 660ND setting? From your previous measurements I am sure you do, so this doesn't make sense.

I don't recall how much current is going into my open can with this regulator, and I would have to de-solder my peltier to check. But I am using a 7135 to power a SenKat diode and it reads exactly 350ma's. Of course I have a 33 ohm resistor in parallel with the diode, so the diode is only seeing ~250ma's.

Click to expand...

Gazoo, I guess I could cut the silicon diode off and measure the power....but I don't know if I really want to! LOL...This is awesome! I ran it for 30 seconds while monitoring the temperature on the face of the heatsink, right above the module. It only raised 1/2 a degree in 30 seconds! I still think it doesn't have anything to do with the silicon diode. (not an educated guess, just a 'common sense feeling') It makes more sense to me, that the difference in voltage to the LD is causing the difference. I have more 7135 drivers, and another open can as well. I think I would rather just build another one without the silicon diode instead of cutting the silicon diode off of this one...

I know this sounds like I am missing something like the ND filter, or the settings of the LPM. Trust me, I have triple checked everything. The beam and dot is noticeably brighter as well. And the LPM reading doesn't lie. I think I will build another one the exact same except without the silicon diode...
Jay

Re: MXDL Over 300mW!

amkdeath said:

dood, leave it as is!! dont mess araound with it, u might kill it, and u may never get a laser at that power with that much input ever again!!

WHat heatsink are you using and where did u get it from?!?!?


I didnt know that 6v is too much for this circuit, that sux... I jsut bought one... so ur saying I shud drill out the tube with 3/4" drill bit and use 18650's?

thanks.

amk

Click to expand...

amk, the AMC7135 is not for 6 volts. Check the specs on the order page and it says some suggested battery combinations. There are other things you can do with the MXDL though. (if you don't want to use 6 volts) I really like the MXDL as a flashlight as well as a laser. Check out this thread:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1194770080
Now that I know how easy this AMC driver is to fit, I have ordered some AMC7135/1050mA drivers just to run a Cree Q5 emitter in the MXDL drilled out to fit a single 18650!
Jay

Re: MXDL Over 300mW!

All I can say is I think you have a freak diode then. Because you said:

"The exact same diode, 30 minutes before I made the change, was running at 324mA and putting out 294.5mW with a DDL driver, which is normal."

And that is not normal either. ;D Running with 324ma's should only produce appx. 225mw's...so what can I say? You have a freak diode.

Re: MXDL Over 300mW!

Gazoo said:

All I can say is I think you have a freak diode then. Because you said:

"The exact same diode, 30 minutes before I made the change, was running at 324mA and putting out 294.5mW with a DDL driver, which is normal."

And that is not normal either. ;D Running with 324ma's should only produce appx. 225mw's...so what can I say? You have a freak diode.  

Click to expand...

Gazoo, correction. I meant to type 194.5 mW. It was a typo...sorry. I am going to edit a note in where I made the typo error.
Jay