DIY Thermal LPM for under $50

lasersbee said:

Nice small PCB.... But are those 10 turn pots or 1 Turn pots...:thinking:

Jerry

Click to expand...

The pads are for 4mm Bourns. Part# 3314 for 1 turn, Part# 3214 for 5 turn, and Part# 3224 for 11 turn.

You can use a one turn pot... calibration and fine tuning will simply be hellish.

LazyBeam said:

You can use a one turn pot... calibration and fine tuning will simply be hellish.

Click to expand...

Yup it'll be worse than try to set a specific current on a full range Flexdrive.

-Tony

Got the TEC and Artic Alumina Adhesive today

I've got my circuit built and painted my TEC and it works pretty well for lasers >50mW or so. But my 5mW pointers hardly register. It'll switch between 0-1mW and 473nm labby which I know is at least 10mW barely registers either.

Also I think the 5k pot is WAY overkill. I only needed about 1 ohm to get the meter to zero.

Another bummer is my 445nm is definitely not 800mW, not even half that, prolly static damage. :undecided:

-Tony

Hi, All "A little Heavy"

I just got my 8x8mm Tec in Yesterday and the new heatsink in today. Iam working on putting that together now.

I made a video showing my 5mW overspec Green laser pointer to show that my meter is Reading it fine but a Little slow to my liking, so that was the purpose of me getting the new TEC hope for it to read a little faster at lower outputs.

Hopeful tomorrow my laser comes in to calibrate it. to get an accurate reading.

@Xplorer877 I hope this video helps you little to see that My meter does read low Power lasers ok but slow. I will go out tomorrow to the dollar store for you and pick up a cheap 1$ laser that are usual the 1mW ones and see what it reads. Also is your calibrated ? and what paint did you use and how many coats did you put?


Now Pic's of the new TEC"I drilled a hole to put the wires through it for a better look"

New TEC:


Both TEC's Left is the 8x8mm Right is the 15x15mm TEC.

jib77 said:

Got the TEC and Artic Alumina Adhesive today

Click to expand...

Gee... that looks awfully similar to a LaserBee Thermopile....:evil:

Xplorer877 said:

I've got my circuit built and painted my TEC and it works pretty well for lasers >50mW or so. But my 5mW pointers hardly register. It'll switch between 0-1mW and 473nm labby which I know is at least 10mW barely registers either.

Also I think the 5k pot is WAY overkill. I only needed about 1 ohm to get the meter to zero.

Another bummer is my 445nm is definitely not 800mW, not even half that, prolly static damage.
-Tony

Click to expand...

I wouldn't put all my eggs in the same basket until you calibrated
your MM designed LPM with a real Known calibrated LPM.. it may just
be your sensor coating or a non-linearity of your input or output..


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

UPDATED: ^^POST 185^^ With new video of the 8x8mm TEC and a couple of pics.:thanks:

It works fine for me now. Mine too is pretty slow with the low powers. On average I'll wait at least 5 seconds before I get a stabilized reading. I just had to tweak the calibration a bit. I know my PGL-III-A is between 130-150mW (from when I had my laserbee I). So it should be calibrated to within 15-20mW or so and all of my other lasers, except my 445nm, are within their expected ranges.

However unless my 6x build is doing +700mW than my 445nm is definitely not 800mW. They both register about 260-280mW on my meter. Besides it never burned any better than my 6x, actually even worse because of the beam profile.

But I don't care. I'm a wavelength guy, the fact that it's blue is cool enough for me. I'll prolly replace it eventually but I'm not devastated. It's still very bright.

I'm still waiting on my volt meter but overall it works great! I'm very happy with it.

I was think about augmenting the circuit with a second calibration pot (R3) to get the meter to read 1/10ths of a mW. I could add a toggle switch to flip back and forth between the two pots. That way I could very accurately measure <20mW lasers. I'd have two ranges.

-Tony

Great you got yours up an running, but what a bummer with the 445nm reading 300mW, i seen your other thread on that

I am a 50/50 person between color and burning i like both. But i would sacrifice burning over color any day..

Hey lazeerer what TEC are you using? It's this one right?

03111-9J30-20CA

Have you measured the resistance across the R3 gain pot? Mine is 3.67k ohms, I think that's within 10mW or so of calibrated. Assuming the paint we used has about the same absorption index, I used Rustoleum Matte Black BTY, we should have roughly the same values.

-Tony

i have been reading this and waiting a bit for stuff and saw this on that site and wondered why no one is using this.
Thermoelectric-Peltier-Mini-Module
its about .25in around the same size almost as a sled optic, so its not hard to get a laser to shine in that area without burning right?
It seems with one that small you would get readings way quicker than say a .5in one right?
Also its not coated with that white stuff like the others.

That one is a bit too small actually. 8x8mm is better. A laser with an Aixiz lens focused with minimum divergence will have a beam diameter of about 6-7mm. Furthermore that one doesn't have as many junctions as the one I mentioned above. Usually the voltage rating is correlated to the number of junctions, so is the price. Don't rely on the picture either, always read the pdf if you can. They have one that has a picture of a TEC with more junctions than it actually does. Also they're not coated with white stuff, that's the ceramic plate. Either way you'll have to paint it. The paint job should be as thin as possible and very even.

The one I'm using works great, even for low powers. It does take a few seconds for the plate temp to climb but you'll have that issue, and it's really not that big of a deal if your patient, with any TEC. If my meter reads zero it will take about 8 seconds to climb up to ~250mW. It climbs quickly and then slows down as it approaches.



-Tony

Xplorer877 said:

-Tony

Click to expand...

What paint did you end up using?

Xplorer877 said:

Hey lazeerer what TEC are you using? It's this one right?

03111-9J30-20CA

Have you measured the resistance across the R3 gain pot? Mine is 3.67k ohms, I think that's within 10mW or so of calibrated. Assuming the paint we used has about the same absorption index, I used Rustoleum Matte Black BTY, we should have roughly the same values.

-Tony

Click to expand...

Hey, Tony iam using the same TEC as you 8x8mm 03111-9J30-20CA
Right now my meter is not calibrated so i tested it at:

Unit Off: Iam Getting 3.06k ohms
Unit On: Iam Getting 1.43k ohms
If i move the gain pot i get different readings

When i calibrate i will re test this and post the update for you. I should be getting my laser any day now. So if i understand correctly this would mean that if my unit is at hypothetical speaking 3.50k ohms Unit Off and 1.50k ohms Unit On that our LPM would be calibrated to give or take 10mW apart from each other?
Aug.13.2010


Aug.13.2010

Edit 2: (Early Evening) I got my laser today an I got My LPM Calibrated now WaHOO!

Tony Here are my final 2 R3 gain pot reading now that it is calibrated:
Unit Off: Iam Getting 3.25k ohms
Unit On: Iam Getting 3.12k ohms

Hope that helps.

^That's great man!!!! Thanks!!!

I'm just using the regular matte black Rustoleum paint and it's working great! I experimented a bit with some of the paints that I had on hand. I had some of that high temp stuff but the problem was that it was kinda glossy. My most powerful mw/mm2 laser is probably my 150mW green laser, since the beam at aperture is very small. All of my adjustable focus lasers have a much larger beam diameter. Anyway, I've had my laser pointed on it for over a minute straight and as you can see in the pic above, there isn't a mark on it. However, the paint can and will burn it >250mW is focused to a pin prick.

-Tony