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MXDL 300 Laser Build
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lazd.net site admin demo - MXDL 300 Laser Build

MXDL Burning Laser Build

The diode source

I purchased these drives from Newegg.com for $23.99 each. I heard about this drive from a thread on LaserPointerFourms.com and heard the diode was quite the burner. I had to find out, as I had plans to build the MXDL burner detailed in Daedel's guide. This wasn't my first diode extraction, I extracted 2 closed cans from 8x burners easily and with success (short of getting one of them out of it's heatsink...), but these long open can diodes are completely different and quite a challenge to keep in working condition when harvesting.


The drive label

I had the AD-7190A. I never tested these drives in a computer, they went from bubble wrap to bench. Note that the AD-7191A has the diode both soldered and glued in place, whereas the AD-7190A is only glued.

Take it apart. There are a few screws, figure it out, get creative. Get the laser carriage by itself.

[ will add pictures/elaboration of taking drive apart, screw ID for needed carriage rail screw ]

The right way to extract the diode

Before you get the diode out, you should cut the ribbon cable going to it, get a pair of needle nose pliers and your soldering iron, and heat all three terminals and remove the ribbon with your pliers. All the solder will be removed except a nice tin in under 1 second of heat exposure to your diode. You could also do this afterwards with a careful hand, help, or a vice. Once you remove the ribbon, get the smallest flathead you have and a razor. Scrape the glue out of the areas around the diode and get the carriage situated in a safe way so your diode has a place to land when it comes out -- you're about to do one of the most delicate parts of the build.

[ THE PICTURE BELOW IS WRONG, POLARITY IS REVERSED! ]
Take your flathead and start gently prying out the diode. You'll of course want to work all sides of the diode a bit until you can get some leverage, but be careful and don't pry carelessly at the tempting dangerous place described above. Once you get a good anchor point on the diode, if your screwdriver is the right size you might find removing the diode quite simple by rotating the screwdriver slowly while leveraging it against the carriage. Here's an animated GIF of some shots I took reenacting the way I pulled the diode out (worked for me 3 times), although I had to go back and forth between sides with my screwdriver before I did this and had to be careful not to send the diode flying.


The diode

My poor soldering job and 24 gauge rainbow wire from RadioShack. Needless to say, soldering those tiny contacts is amazingly challenging.

[ retake the above picture, it sucks ]

The circuit

Here's the LM317 current regulating circuit I built from Daedel's guide to test on breadboard. First I used a 0-100ohm potentiometer to test current levels at various resistances (you should use a resistor in series with the pot to set your minimum resistance to ensure you don't go to 0). I then took two 1/4 watt 5.6 ohm resistors in parallel, giving me 2.8 ohms and the 1/2 amp rating required and bridged the Vout and Vadj pins with them, taking care to connect the wire going to my diode/capacitor combo to the Vadj side of the resistors. Test the circuit with rog8811's DDL test guide, you won't be sorry. I kept a 1 ohm resistor in line to monitor the current in milliamps by using the milivolt selection on my ohm meter.
[ possibly give links to where to get parts besides radioshack ]


I blew a diode up somewhere between getting my CR123s (note: 3.0v CR123, not the recommended 3.6v RCR123) and hooking it up with 2.8 ohms across the LM317. This was probably due to heat or too much current/spike from the potentiometer. Takehome: Save yourself some cash and be extra careful. Use a resistor of the minimum safest value in series with the potentiometer and be extremely patient and relaxed when you remove the diode. Don't get frustrated when you screw up (and when you do, take a break).


Getting the diode into the Aixiz module

You'll need a vice and some clever plastic pieces to get the 10mw diode out of the Aixiz module and insert your freshly harvested 300mw diode. I took a blue wire connector that fit nicely in the top of the module and a tiny slice of bubble wrap to protect the diode and closed the vice on it, loosening and rotating a few times to gently pop the old diode out. I was able to get the 10mw out with only slight bending of it's case and no damage to the glass portion -- it still worked when I tested it. I then carefully placed the new diode in the back and pressed slowly around it's edges, a little at a time on each side in an alternating triangle pattern, much in the same way you'd tighten lugnuts.
[ post pictures of vice diode removal and inserting , talk about where to get the modules ]

Building the driver circuit

After I finally got my MXDL flashlight bodies from DealExtreme, I set about creating a circuit that would fit effectively and be as completely clean as possible. I had to remove the tab from the LM317 with a grinder, and decided laying it flat would conserve space best, although this may not be ideal for heat transfer.


It fit perfectly. Keep in mind that 2.8 ohms will give you a seriously aggressive burner and may or may not negatively affect the life of your diode.


Adding the protective measures

After I built the driver, I had to find a way to get the capacitor, which protects against voltage spikes, and the 1N4001 diode, which protects against accidental polarity reversal, all inside the Aixiz module -- without shorting. My first setup immediately failed when I accidentally unscrewed the wrong part of the MXDL, then as I rebuilt it with a fresh diode, my poor electrical taping job around the cap gave way and it shorted, destroying another diode. Takehome: A foolproof heatshrink job on any components in the module is the only way. I am certain my current setup cannot short, unless the wires were twisted 10+ times. Speaking of twisting, don't unscrew the MXDL in the middle unelss you've removed the top cap, allowing your heatsink to spin -- this will twist your wires internally, and if you use stiff wires, this can blow things up.

Here's how to avoid shorts in the Aixiz module: This was my third try -- electrical tape is NOT fool proof, use heatshrink.

Putting it all together

Be careful, be patient, have a steady hand, take a break before you finish.



[ post pictures of heatsink itself, arctic silver around the module, explain heatsink creation, give source to buy via jay ]

The end result:
















Sorry, no burning pictures yet. Don't be put yourself at risk, buy goggles before you do anything that involves staring at laser light

After I got my Ultrafire LC 16340 3.6V 1000mAh Protected CR123A batteries and charger from DX, I double checked my circuit -- the output was exactly 421ma, my target. I crossed my fingers, put on my goggles, and situated some electrical tape on some wood 3 inches from the lens. I focused the beam on the tape and it smoked instantly. When I pulled the tape off, I noticed the wood had a small mark on it. Curious, I tried to burn the wood and great success was had -- i was able to draw lines and write my initials on my porch with a laser. I then situated a match directly in front of the wood I had been burning and began to turn the laser on -- before the switch released entirely into ON mode the match was in flames -- it was seriously instant.

[will add pictures of burning, more beam shots, focused beam shot with fast shutter ]

If this looks cool, but way too complicated, don't worry! I sell these lasers pre-built exactly as above with the open can diode and any resistance you desire (2.7 - 320mw estimated, to 3 ohms - 300mw estimated, to 4.5+ ohms - <200mw estimated), heatsink, Aixiz module with glass lens, 2 1000mah 4.2V protected batteries, a compact charger, and your choice of NoIR goggles for $250-$300 shipped (depending on your choice of goggles) anywhere in the U.S., contact me if you're interested.
[ I've got some hurdles to jump as far as warning labels, keys, interlocks, delays, and audio/visual power indicators before this can be sold as a hand held lab laser, give me some time! In the mean time, build your own! ]

You can also buy a laser of similar power, but made out of plastic and with no batteries, no charger, and no goggles for $529 plus shipping from Blaze Lasers, who claim "There are no better deals than this anywhere online!" I scoff at this notion and raise them 20mw.
[ BlazeLasers site is down. Who knows when they'll come alive again ]


Protecting your eyes and using your laser properly

First off, laser light can damage your eyes. 300mw of laser light can really damage your eyes. You simply must have goggles if you use this laser for anything but pointing out stars.

I should soon be a reseller for NoIR goggles and can sell you OD1.5-OD3 goggles specifically for red laser light for ~$100-$125 shipped to anywhere in the U.S., contact me if you're interested.

If you value life as you know it and your personal freedom: Do not point this laser at people. Do not play with your cat using this laser. Do not point this laser at airplanes. Do not point this laser at cars, boats, trains, heavy machinery, houses, bicycles, horse drawn carriages, reflective things, glass things, your eye, your skin, your friends, squirrels, officers of the law, anything white, anything shiny, and anything black that you would rather not see catch on fire. Takehome: Don't do anything stupid.

Cycle your laser. Don't keep it on for longer than a minute without 30 seconds or more to cool down, especially if you skimp on the heatsink.

Also -- It's not waterproof. It says it's 5w, super bright, waterproof, and made in the USA on on side of it -- none of this is true at this point. It's 300mw, brighter than the sun, quite susceptible to liquids, and was definitely manufactured in China and rebuilt wherever you are. So you might want to cover it up with a laser warning sticker or something that identifies the laser properly.

Some notes on the build:

  • As heat increases, internal resistance in the diode decreases, therefore the current drawn increases. This is part of the reason a driver is required; to keep current at a constant level.
  • LM317 will turn off at 170C
  • If using a heatsink (in addition to the laser module of your choice), smear the laser module with Arctic silver thermal paste when inserting into heatsink for maximum heat conductivity.
  • Output of LM317: i = 1.25/R
  • Quote from LaserPointerForums: "I just wanted to add that the output of my first MXDL 300 is "only" 215mw's using CR123 batteries. It is drawing around 350ma's. This is further evidence the CR123's have a rapid drop in voltage, and the 317 drops out of regulation. With RCR123's this will not be a problem. I have [3.6v CR123A protected 1000mah batteries] on the way from DW and a charger on the way from DX."
Goggles!