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ArcticMyst Security by Avery

Converting a Labby into a portable

Joined
Jul 9, 2007
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This quick tutorial will take you through the steps of converting a lab style laser into a "box" portable, like my frankenstien laser.

I will be adding pictures later when I get a nice Alu box for my frankenstien. The steps however are pretty straightforward.

Tools you will need:
Assorted screwdrivers
A multimeter
A regulated DC power supply or the battery in the parts required section
A soldering iron and solder (a 25 watt iron will be sufficient)
A set of jewelers screwdrivers

Parts you will need:
A 6 or 7.2 volt rechargeable battery - choose an nimh
A box to fit all the bits in. Choose aluminium to act as heatsink
A laser driver that will suit the current range your laser uses. I got one from meredith instruments, but ended up building my own as I was impatient waiting on the post.
A switch (I used a missile switch)
A Key switch for saftey (I used a tube type)
Assorted hardware


Now lets get to building.
First of all we are going to need to get the top off the original mains powered laser driver. We need to measure the current going to the LD. Remove the top of the laser driver, and the back end of the laser head so you can identify which wire goes to the diode. Mine were red and black to the diode, blue and yellow to the tec. They will be the thicker set of wires. You will also have 4 thin sets, two to the thermister and two for the fan.

Once you have identified which wires go to your diode, place your meter in series with the diode leads at the power supply end, set it to 10A current range and ensure the meter leads are in the correct holes for this task. My leads were attached to the driver guts via screw in terminals - so I screwed the black lead of my meter under the screw in terminal, and attached the red lead to the red wire of the head to the red lead of the meter with a thick wired crocodile clip.

Apply power to the laser and allow it to fire. Pointing the laser somewhere safe (I used a black heatsink as a beamstop), watch your meter. Give the laser a minute or two to settle, then note down the reading. Mine measured 900 ma

Switch off your lasers mains powered supply. Disconnect all the leads from the mains supply going to the head. Twist the laser diode leads together for now to prevent static damage.

If you are not going to be powering the tec, remove it from the head. This will allow heat to be transferred from the pump diode to the heatsink. An unpowered tec will simply act as a heat insulator. We dont want this. This should be pretty straightforward. I did not power my tec. Reassemble the head with or without tec.

If you are going to drive your tec, I'll leave that up to you. You can use the inbuilt thermister to run your tec at the correct temperature. I didnt run my tec so you are on your own here.

Attach screw standoffs to your LD driver for the laser diode connections. Connect the red lead of the diode to the A connection, and the black to the K connection.

Attach the key switch and switch via a red wire to the +ve connection on the driver board, and connect a length of black wire to the negative connection on the driver board. Solder a pair of screw terminals to the LD current test points, or use wires with crocodile clips. Adjust the trim pot on your laser board following the instructions, to supply minimum current.

If your laser driver is home built and has no provision for current measurement (!) you can place your meter in series with the laser diode again, like you did when getting the initial reading off the mains powered supply.

Attach a suitable connector (observing polarity) to your switch and black lead, to suit your battery pack. I used a 6 volt radio controlled airplane reciever pack, and the connectors came with it for different model recievers. I simply chose a pair, lopped the other end off, and connected those to my switch and driver. Turn on the key switch so it wont interfere with testing.

Connect the battery connector to your charged battery, or the DC power supply set to 6 volts. A 6v lantern flashlight battery will do in a pinch if your battery has not arrived yet.

Connect your multimeter to the current sense testpoints.

Slowly turn the trim pot in the directions to increase current. Point the laser at a black or nonreflective surface, and continue turning until the laser lases. You will get a negligable reading on your meter up until this point. I thought I had busted my laser until it finally lased at around 700 ma. I cranked mine up to the reading I took (900ma) and gave it 100ma more just for good measure (like a pot mod, its up to you if you wish to do this). Once you have reached your target value (in my case 900ma) you laser is ready for boxing up. Disconnect your power supply, multimeter, and the lengths of wire to the current sense test points. Attach the charging socket in parallel to the battery leads. Connect the fan of the laser head to the point after the switch, and the negative of the battery, observing polarity. For extra saftey, I connected mine to the point between the on off switch and the key, this way whenever the key is on, the fan is running regardless of wether you have the beam on.

Once boxed up, you will have a seriously powerful burning DPSS laser that you can use anywhere away from mains power. If you're like me, place a small computer fan in the laser, blowing out, and add some cooling vents. I was concerned about the lack of TEC in mine, so added a fan at the back, which drew air through holes in the side. Mine is yet to make it into an aluminium enclosure.

ISOLATE THE DRIVER BOARD FROM THE BOX. This will prevent any mishaps as the laser diode is usually grounded to the case of the laser head assembly. I simply attached a small heatsink to the driver board's transistor (it barely gets warm) and wrapped the whole board in electrical tape as insulation, excluding the heatsink. I then used zip tie bases and zip ties to secure it to the inside wall of the box. Its not going anywhere.
 





Joined
Jul 9, 2007
Messages
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Thanks Things.

now if I could just find the ms paint equivalent on my mac, I'd be able to draw up the circuit diagram for people to follow...
 




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