DIY Thermal LPM for under $50

Yeah I'm still working on mine too.

Hey Mario, when I finish mine could I send it to you to calibrate for me? I'd pay you for your time and the shipping round trip. Truth be told I don't have a known >100mW laser. I have an idea of where they are but only to about +-20mW. There really isn't any point for me to make this project unless I can have it properly calibrated.

-Tony

Sure I could calibrate it, hopefully in the near future I will have a very accurate source to calibrate to

i hit a speed bump (mario you already know what happened ) may get it finished tomorrow
cheers

Cool thanks buddy.

Another thing I just thought of is that the TEC will generate a voltage proportional to the difference between the two ceramic plates. So the hot side would be the side that the laser shines on and the cold side would be attached to the heat sink. So a consistent reading will also rely on the same ambient temperature of the room at the time it is calibrated. The Laserbee would also be affected by this. It might mean that the reading may shift quite a bit depending on the temp of the heatsink.

If the room was 60 deg and you got 100mW lets say, then if you test again in 80 degs with the same laser the difference would be -20 degs resulting in a reading less than 100mW. It could be significant if it was a really hot day.

-Tony

UPDATE:
Mario your LPM...............................WORKS
although it is crappy ATM i need to get a smaller tec...........
IF ANYONE SAIS I TOL YOU SO......Grrr.
i just wanted to make sure it works. i am now getting a small tec
cheers

<10-8mm would be ok soo yeah

not gunna work man...
anyone got a dead T-03 diode with the tec they dont want??
may be usefull for me

He's talking about when you get a small TEC.

It's not just the size of the TEC. You want to get a small one that has the most junction density. That way your laser will stimulate more of the tiny cells that actually make the voltage.

03111-9J30-20CA



Yeah it's expensive, but look at how small it is and how many little squares it has. those are the cells that make the voltage that is amplified by the IC. So the more resolution your TEC has the more accurate it will be overall. Also you want the TEC to have an input of at least 3v. You also must use a good voltmeter.

This project is cool but has it's flaws. The TEC resolution, the voltmeter, ambient temperature, and the paint that goes on the TEC, all effect the accuracy. It's important to try and use the best of everything to get a good meter.

-Tony

Hi, Iam going to be making one too. Thanx MarioMaster for this DIY It is awesome. I just wanted to make sure i had everything correct before ordering the stuff. I could not find 2 things i will list them below.

OK Here is what i got i hope its right:

1x LM358 IC From Here:
LM358N LM358 358 Low Power Dual Op-Amp 8 Pin DIP

1x 10K ohm multi-turn precision potentiometer:
I could not find one Can you please help and provide a link. Much Appreciation.

1x 5K ohm resistor From Here:
5W 5K ohm 5% Power Wirewound Resistor: In Stock Buy Now | West Florida Components

1x 5K ohm standard potentiometer:
I also could not find one of these can you please help with a link. Thanks

1x 1K ohm resistor From Here:
1K ohm 1/2W 5% Carbon Film Resistor pk/5 - RadioShack.com

1x 0.1uF capacitor From Here:
0.1 uF Metallized Polyester Film Capacitor - RadioShack.com

1x voltmeter I have this one Let me know if this one will work for this Project:
DT830D Digital Multimeter Meter AC DC sound Pocket Mini on eBay.ca (item 320455938201 end time 28-Jul-10 01:29:46 EDT)

1x small TEC module From Here:
03111-9J30-20CA
Now when i order this do i select under "Moisture Sealing" the unsealed or the moister sealed, witch iam 99.99% sure its the unsealed one.But just want to make sure.

1x heatsink From Here:
Digi-Key - 102-1489-ND (Manufacturer - VHS-95)

Project box:
Still looking...:undecided:


So I just need some help locating the 10K ohm multi-turn precision potentiometer and the 5K ohm standard potentiometer?

This will be my first attempt on make something like this/level of difficulty so i appreciate all the help already provide by everyone in this thread and further more. Iam so excited to make this and i cant wait to put this together.

Thanks again in advance for the couple of parts i need help finding.

lazeerer you can get almost all the parts from ElectronicGoldmine.com

LM358 amp
LM358P Dual Operation Amplifier (TI)-The Electronic Goldmine

I recommend one of these for the amp
8 pin IC Socket-The Electronic Goldmine

.1uf Cap
.1uF Disc Capacitor (Pkg of 10)-The Electronic Goldmine

5k trimmer pot
5K PC Mount Trimmer Pot (Pkg of 4)-The Electronic Goldmine

20k multi turn trimmer (Yeah I know it's supposed to be 10k but 20k will work too)
20K Multiturn Trimmer Potentiometer-The Electronic Goldmine

They also have the resistors and lots of heatsinks and boxes to choose from. If you get them all from one place you'll save on shipping. It's easy to buy all kinds of goodies from there.

You'll also need some thermal adhesive to glue the TEC to the heatsink. I'm going to get some Arctic silver adhesive but they don't have it. You can find it here:

http://www.amazon.com/Arctic-Alumin...?ie=UTF8&s=electronics&qid=1278951247&sr=8-10

I'm still not sure what kind of paint to use to coat the TEC though.

-Tony

TTerbo said:

anyone got a dead T-03 diode with the tec they dont want??
may be usefull for me

Click to expand...

Chris (heruurscience) had some of them, but actually he sell only directly ..... maybe someone that is living in the same zone can act as "distributor" ?

OK... I don;t know too much about electronic componets so could one of you smartypants p) check the stuff I picked out?
I'll have to buy a better DMM anyways and my heatsink will be an old OEM AMD CPU cooler (drilled out) with fan.
I'm planning on mounting everything to a radioshack predrilled board. Everything else can be bought @ digikey.
Guys, feel free to use my links to build your shopping cart... assuming that I chose good parts.

1X OP-AMP... LM358NFS-ND or LM358ANFS-ND or 296-1395-5-ND ($0.46) (Help me decide ??)
1X 10k multi-turn pot ... 3009Y-103LF-ND ($2.72)
1X 5k single turn pot ... CT6ER502-ND ($0.71)
5X 5k 1/2W resistor ... PPC4.99KXCT-ND ($1.09 )
5X 1k 1/2W resistor ... 1.0KH-ND ($0.31)
1X TEC Module ... 102-1672-ND ($15.18) or 03111-9J30-20CA ($38.25) (Help me decide ??)
1X 0.1uF Capacitor ... 493-1095-ND ($0.17)

TOTAL: $20.64 or $43.71 depending on the TEC you choose.
IMO, a larger 15mm TEC would be fine because you can just widen the beam diameter to 10mm-14mm.
If you wanted to measure power @ the aperture or when tightly focused (why??) then go with a smaller TEC.

Xplorer877 said:

lazeerer you can get almost all the parts from ElectronicGoldmine.com

LM358 amp
LM358P Dual Operation Amplifier (TI)-The Electronic Goldmine

I recommend one of these for the amp
8 pin IC Socket-The Electronic Goldmine

.1uf Cap
.1uF Disc Capacitor (Pkg of 10)-The Electronic Goldmine

5k trimmer pot
5K PC Mount Trimmer Pot (Pkg of 4)-The Electronic Goldmine

20k multi turn trimmer (Yeah I know it's supposed to be 10k but 20k will work too)
20K Multiturn Trimmer Potentiometer-The Electronic Goldmine

They also have the resistors and lots of heatsinks and boxes to choose from. If you get them all from one place you'll save on shipping. It's easy to buy all kinds of goodies from there.

You'll also need some thermal adhesive to glue the TEC to the heatsink. I'm going to get some Arctic silver adhesive but they don't have it. You can find it here:

Amazon.com: Arctic Alumina Thermal Adhesive (Two Tube Set): Electronics

I'm still not sure what kind of paint to use to coat the TEC though.

-Tony

Click to expand...

Man You are awesome. Thanks for taking that time to post the individual parts from the site i will get everything from there then I really appreciate it +1

I cant wait to get this going i will order everything on Thursday when i get paid.

thanks: again.

lazeerer said:

Man You are awesome. Thanks for taking that time to post the individual parts from the site i will get everything from there then I really appreciate it +1

I cant wait to get this going i will order everything on Thursday when i get paid.

thanks: again.

Click to expand...

No problem buddy.

-Tony

this may help
it sure helped me make my LPM one sided PCB



negative of the battery goes to negative of the tec.