DIY Thermal LPM for under $50

^^^^ Been there... Done that^^^^

It requires specialized equipment to cut the ceramic
plates BEFORE they are assembled...
Just the vibration of a cutting tool can damage the
PN semiconductor junctions... not to mention the
heat that can be generated by some high speed
cutters..


Jerry

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

Maybe I'm just awesome? I used a glass cutter and scored both sides of a 40mm x 40mm tec, pressed on the seam and snap - it broke right in half. Soldered a wire to the last junction in the series and it was up and working.

Benm said:

It is all about assumptions really. Assuming any measuring device absorbs 100% of incoming radiation is a big step, but not unreasonable unless you have information that proves otherwise.

My idea with the whole concept of using resistors as heating sources was to build something with about 10% accuracy. If you want to go further than that 10%, there are many problems to consider, even the accuracy of your voltage meter if you want to go towards 1% or so.

I still believe a 10% accurate power meter is a valuable asset to anyone experimenting with lasers though... especially since it will show a more-pwer-reads-more-response for tuning systems, regardless of actual accuracy.

Click to expand...

Times ago, i tried something similar with a 40x40mm TEC (i was not sure if i had this thing around, so i searched before post) ..... the thin wire glued (with superglue ) on the upper plate is constantane wire, that i had around ..... i used a piece of exactly 10 ohm, and used it as "thermal calibration element" ..... the reading from the thermal calibration was working good enough, but the too big plate was not good for the laser reading ..... it was needing too much time for thermal stabilization, and also not working good under 100mW, so i abandoned the idea ..... maybe reaching to do something similar with a 10x10, or 6x6 TEC. it can work better .....

But, basically, that what i meant is, the item that you use for "paint black" the absorption zone, influence a lot the reading ..... when i made these tests, calibrating it for 200mW, then reading from different known lasers (200mW IR, 120mW blue, 180mW red, 115mW green, all measured with a calibrated instrument), i had very variable readings, changing also around 35-40%, from color to color, using different "black coatings", also if the thermal calibration reading was always the same ..... so, that what i meant was, yes, the system is good for calibration, but only if we find a reliable and efficent black coating, with an absorption index that is almost flat, from IR to UV .....

MarioMaster said:

Maybe I'm just awesome? I used a glass cutter and scored both sides of a 40mm x 40mm tec, pressed on the seam and snap - it broke right in half. Soldered a wire to the last junction in the series and it was up and working.

Click to expand...

You was very lucky ..... or you have a career in the glass industry, the one that you prefer from the two

MarioMaster said:

Maybe I'm just awesome? I used a glass cutter and scored both sides of a 40mm x 40mm tec, pressed on the seam and snap - it broke right in half. Soldered a wire to the last junction in the series and it was up and working.

Click to expand...

You had better luck than I did.... So I guess your mommy was
right... You are awesome...:crackup::crackup:
J/k


Jerry

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

HIMNL9 said:

...
but only if we find a reliable and efficent black coating, with an absorption index that is almost flat, from IR to UV .....

Click to expand...

Do you think Krylon Ultra-Flat Black spraypaint would work?



Krylon Ultra Flat Black Spray Paint #1602. SHIPS BY GROUND ONLY
or
Amazon.com: Interior/Exterior Paint 12oz -Ultra Flat Black: Kitchen & Dining

should be good, you should look for flat black paint for engines that has a high heat tolerance

Ash said:

Do you think Krylon Ultra-Flat Black spraypaint would work?

Krylon Ultra Flat Black Spray Paint #1602. SHIPS BY GROUND ONLY
or
Amazon.com: Interior/Exterior Paint 12oz -Ultra Flat Black: Kitchen & Dining

Click to expand...

Don't know this one, i asked my paint shop, but they don't have it ..... i used for some experiments a paint that is used for paint exhaust tubes in motorcycles, so is marked as "high temp" ..... is the code 954 from Hasai Color, but i don't know if is possible to find the same paint brand outside Italy (i suspect that Hasai is a rebrand from Iveco, but i'm not sure about that) ..... anyway, after some experiments, i found a way for make a very opaque surface (much more than the normal paint layer itself), so it's ended in a decent absorption surface .....

It's very difficult to explain it just with words, and actually i have no way for make a video, but i try ..... i do the first layer of paint normally, then left it dry for an hour (this give a flat and matte surface, but still with a certain reflection index) ..... then i do a second light layer of paint, left it dry for some minutes (just until it become opaque), then spray some other paint in very quick shots, from more distance (like if you make "rain" the paint particles, instead spray directly over the surface) ..... this give a surface much more opaque and less reflective than the normal painting .....

I've got some of that Ultra Flat Matte Black, but haven't done any tests vs. other paints. Another thing to try is some high heat grill paint like this.

Remember, the thicker the paint, the more thermal mass you have to deal with.

hey i have all the parts to make this but i cannot start because i need to etch the PCB so Mario could you or someone please email me the printoff versin of the 2 sides.
cheers

TTerbo said:

hey i have all the parts to make this but i cannot start because i need to etch the PCB so Mario could you or someone please email me the printoff versin of the 2 sides.
cheers

Click to expand...

Rather than etching the board, you can also test it out with a breadboard/perfboard, and considering the size of the parts, you could even just connect it using wire.

i am going to use this for my 3/4 science thing. it has to be neat to get full marks. so could anyone email me the attachment to the eagle design so i can print it of to scale?
cheers

MarioMaster should be able to help you with that...
It is his DIY project...:yh:


Jerry

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

yeah i hope so, because i cant etch the pcb unless its to scale!
cheers

http://dl.dropbox.com/u/1181169/easylpm.brd

you can download the board layout file here

thanks but is that the finished design?
if so thanks

I'm going to make one. Parts are ordered, cept the TEC.

You guys seen this?

Mini TEC cooler modules

Of those what would be the best???

I'm thinking the lower wattage TEC might have better resolution that a higher wattage unit, but I'm not sure. They all have about the same temperature rating. Also the input voltage is .85v, so would that be the limit if it was to work in reverse, 850mW?

http://www.shop.customthermoelectri...moelectric-Peltier-Module-00711-5L31-04CB.htm

-Tony