Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

Buy Site Supporter Role (remove some ads) | LPF Donations

Links below open in new window

FrozenGate by Avery

DIY Thermal LPM for under $50

It would be good to plot out your data if you get a chance, because you can still take that information and make an op amp put out 1mV/mW if you still want to go that way.
 





I ordered parts for my soundcard DAC yesterday but I forgot about researching if I need more parts for completing my LPM. I need a reference LPM or laser in order to fully calibrate, but for now I am content with a "ballparking" LPM, and for that all I gotta do is multiply the voltage out of my TEC by -14.

Now I've got 3 types of op-amps on hand right now, left over from my LED driver experiments. I've got quite a few LM741, several MCP6004 (this is a quad) and 3x TLV274I (also a quad).

I see that in this thread folks have been using LM358. I think the reason is that LM741 cannot function without a negative voltage supply.

So what I'm wondering is these MCP6004 I have are good enough.. The specsheet says it "operates from a single supply voltage as low as 1.8V" which sounds promising. Unfortunately most datasheets go into far too much detail and don't go over enough of the basics for me to follow along.

For my soundcard DAC I ordered several TL072 which is a dual version of TL071 which I understand is a more modern (JFET) rendition of the 741... so it will still need a negative voltage so I can't use it here.

I think I'm gonna go sketch up some circuits and play around on my breadboard... please do correct anything I say that is inaccurate, it will help a lot!
 
First of all: My sincerest apologies for necrothreading to everyone.

I got two PCBs from back when jib77 ordered them and offered a few for sale and would like to build this LPM finally. I realize that the limit is 2W but I look at this as both an interesting project for a noob like me and an experience in SMD soldering.

Below is the list of components I was planning on ordering. If it is not too much to ask could I get a feedback from more knowledgeable people than I am whether the parts I have found are good and acceptable for the project. Thank you very much in advance!

LM358N

5K trimmer

10K trimmer

5K resistor

1K resistor

0.1uF capacitor

Thermal Adhesive

LCD

TEC

Spray

HeatSink
 
Last edited:
My DIY LPM is b0$$ with 16 bit delta-sigma ADC + 24 bit oversampling + 3rd. order hardware input filter/buffer. Fully USB 2.0 compliant + Data logging. :D

zallusfront.jpg
 
random person said:
My DIY LPM is b0$$ with 16 bit delta-sigma ADC + 24 bit oversampling + 3rd. order hardware input filter/buffer. Fully USB 2.0 compliant + Data logging. :D

zallusfront.jpg
Click to expand...

That is pretty boss for a DIY LPM, :beer:

How much did that cost you to make?
 
Yea, its not the same construction. To be fair, the pcbs made it cost more than 50 all together but per unit, its under 50 :)

Yea, thats one rather large problem with attempting to use some pre built volt meter. I'd avoid that and do it all from scratch. Then the 0 calibration is very easy from the micro side. In addition, these sensors don't truly have a linear response. You can then also easily implement a mW to count conversion profile based upon calibration from a high end industry meter.
 
Last edited:
random person said:
Yea, its not the same construction. To be fair, the pcbs made it cost more than 50 all together but per unit, its under 50 :)

Yea, thats one rather large problem with attempting to use some pre built volt meter. I'd avoid that and do it all from scratch. Then the 0 calibration is very easy from the micro side. In addition, these sensors don't truly have a linear response. You can then also easily implement a mW to count conversion profile based upon calibration from a high end industry meter.
Click to expand...

Would you be willing to sell that circuit? :)
 
gillza said:
Um :) so do the parts that I listed seem ok to you guys?
Click to expand...

Not sure about the TEC, but you need one with a lot of junctions within a small area. If you want tu use such a LCD panel like the one you pointed to, you will either need a separate power surce or a DC to DC converter. The trimmers should be multi turn precision trimmers.
 
honeyx said:
Not sure about the TEC, but you need one with a lot of junctions within a small area. If you want tu use such a LCD panel like the one you pointed to, you will either need a separate power surce or a DC to DC converter. The trimmers should be multi turn precision trimmers.
Click to expand...

Not sure about your paint... high heat is good and all but is that an ultra flat black paint? You ideally want as little reflection as possible.
Click to expand...

The paint will be switched to this:
High Heat 12 oz. Flat Black Automotive Spray Paint-248903 at The Home Depot

The trimmers are the ones that jib77 used for his setup.

TEC will be switched to this: 430801-504 Laird Thermal Products | 926-1023-ND | DigiKey
MM recomended these.

As for the DMM i'll either use another battery or will use my existing voltmeter from HF
 
Last edited:
random person said:
My DIY LPM is b0$$ with 16 bit delta-sigma ADC + 24 bit oversampling + 3rd. order hardware input filter/buffer. Fully USB 2.0 compliant + Data logging. :D

zallusfront.jpg
Click to expand...

Thats pretty awesome!

Are you willing to share the board files and code?
 
I don't think he will because he is trying to sell them.
Although I'd buy it from him even if the files are released to support development and because I'm a big noob when it comes to Electrical engineering :)
 
Last edited:
You must log in or register to reply here.


Back
Top