The design is not yet final but here are some stuff that I have finished.

I started with a heatsink from FT (link) and machined it to accept a 12mm stubby module from DTR.


I like this new module (haven't seen it before) It makes good contact to the back part of the 9mm diode for better heatsinking.


The heatsink does seem "a little" small for the job but this will be fan cooled so the large surface area with the fins will help. I won't know until I get this all arranged and powered up.

Once the module was in, I had to test it. First light!!! (fan behind the heatsink for cooling)


2.9W at 2.3A with a G2 lens.


Machining makes a bit of aluminum dust


Planned arrangement of the parts


Heatsink and driver will be placed inside the PVC tube to make a wind tunnel for more efficient cooling.

Since I got an average efficiency diode, I'll probably be underdriving this at around 2.2A for less heat. 2.5W should still be plenty for burning stuff. Hopefully, I get to complete this before the new year so that I can use it to light fireworks.

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Love to see how this turns out but slightly worried about the size of the heat sink. IMO its not large enough to handle a 9mm for more than 30sec on 60 off. Yes the area of the heatsink might be large but there isn't much material there.

Yeah, I'm thinking about it too. But once I get to test it I'll change it if necessary to handle the heat of the 9mm.

Worst case, it'll end up as a labby with a larger fan haha

Since it's actively cooled the heat shouldn't build up too much that when passively cooled. Well, at least in theory.

Why don't you entirely drill out the heatsink so that more of the module contacts the heatsink.

That's all the depth my micro mill could drill into. I don't have a lathe in my workshop. I think it shouldn't be a problem since most of the thermal connection of the diode is at the back (aluminum back cover) so I made sure it sits flat with the heatsink with heat transfer compound all over.

if you could get that copper module all the way in i think that heat sink will be plenty.

It's the deepest I could drill using my micro mill. I would risk breaking the bit by going deeper and if I use a drill, the bottom surface won't be flat which won't get good thermal contact to the back of the module. We'll find out soon once I can do some more tests

A little update on the electronics side. (For those that don't care about how the circuit will work, just scroll down for the pics )

We start with an off the shelf driver. We take two of [this] and modify it.

The circuit is basically what's in the LTC1700 datasheet. Even the part numberings on the PCB are the same!

So this "driver" is basically a 4.2V to 5.18V step up DC to DC converter with a 1 ohm current limiting resistor. Much like you'd add a resistor in series with an LED to be able to operate it in higher voltages. It works but isn't very efficient and a small change in the diode Vf changes the output current and we don't want that.

The solution? I used a ZXCT1009 inserted in the circuit feedback path and a few parts changes to make it a constant current supply. So we set one at around 1.1A, the other at 1.4A and then parallel them. Add switches and connect them to the RUN/SS pin of the LTC1700 and you can control the output much like a TTL control

I used two in parallel since I'd need over 2 amps for the 9mm diode and I've tested that one could push up to only 1.8A.

The advantage would be by using two buttons, pressing only one gives either 1.1A or 1.4A current, then by pressing both at the same time, you get full power!

This is getting too long. On with the test setup pics.

Modified drivers wired in parallel



I changed the inductors since the original one cracked from too much fiddling. I didn't have the right value on hand so I used the nearest one.


Test setup. Large string of 3A diodes and amp meter test load. Power source is 2x Panny 3400 cells in parallel.


Both drivers ON. Sorry it's fuzzy, camera couldn't focus on the display


I might drop the maximum current by a few notches but I didn't have the right resistor value so I'll be rummaging through the scrap boards but it's getting late so it'll have to wait.

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A little more work done tonight.

I decided 2.5amps might be a little too hot so I put both drivers back to 1.1A. Then I was able to make a small bracket/heatsink that mounts behind the diode heatsink.

The white rubbery thing in between the drivers and the heatsink in the middle is thermally conductive silicone pad.





Here it is powered up and the drivers in standby mode


I used only one button for now and when you push it...

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Today's progress:

I made a bracket/sled type thingy to hold the batteries, switch and everything else together.


I also added a battery gas gauge so I know when the batteries need charging. This thing draws about 3-4amps from the batteries since I used two boost drivers.


I was supposed to go to the farm on Wednesday to use the lathe there but I couldn't wait so off to my micro mill again.

I let it go as deep as I could and used the shortest lenght of PVC that can hold the heatsink in place so it would fit in my mill.


Seems to ave worked. Here it is assembled and in standby mode.


Toggle switch is the main power switch. Pressing the button opposite the toggle switch turns the laser to full power


3.1Watts of blue! Sorry about the blurry pics. My hands were a little more shaky than usual at the moment.

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Even after a year since giving up facebook (new years resolution 2013) I find myself looking for the "like" button on this post. I've kept an eye on this build. Nice job. What color of spray paint are you going to finish it off with? Merry Christmas!

Thanks, I'm not really sure yet. The PVC tube is sort of temporary and I also need to make a cover for the electronics part. I think I also need to make a guard for the fan. My finger touched the blades a few times while playing with it haha

I wonder if a black plastic stand-up extension tube for a shop vac would be the right size for the external sleeve?

Questions, can you hear the fan? I know it might sound a little silly, but I've been thinking about some sort of sound effect when the rig fires up.

Blue and orange might look cool.....

My other issue would be that I think paint has a hard time sticking to PVC. I'll try and keep a lookout for a nicer tube.

The fan is a little noisy since it is not the best quality but it does the job

One thing I noticed, I powered this on side by side with my 1.7W and this one is a lighter blue. I'm guessing it's a shorter wavelength. 445nm? 440nm? Let's see if the camera can pick it up...

Lighter blue? It should be higher than 445nm then.

You have a lot of interesting builds lately. Keep us posted.

Rep when I can.

Haha sorry my mistake. I was typing in a hurry and mixed them up.

It's christmas vacation so I have a bit of spare time to work on laser stuff

Here are some pics I took just now.

I think I'll keep the PVC. Having the heatsink protrude just a bit allows me to touch it and see if it's getting hot


LPM reading


Scorch marks


Everyone's favorite... Top: 1.7W laser Bottom: 3W laser

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