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ArcticMyst Security by Avery

A (potentially easy) $25 DIY USB Data-Logging LPM?

rhd

rhd

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This USB device was just listed on DX
USB Thermocouple Measurement Device
It claims accuracy of 2 degrees within the*0-700 degree range,*and 5 degrees within the 700 to 1,000 degree range (all in celcius).

My thinking -

Could we not simply apply the *secret proprietary black LPM coating* to the sensor, or alternately, to a small piece of copper coupled with the sensor, and create a $22 LPM?

It would need calibration of course. However, it can output to an Excel file, so once you knew the calibration constant, it would actually be remarkably easy to have two columns in each excel output (one with the data from the device, and the other with a formula that applied the calibration data).
 
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rhd

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lasersbee said:
Wow... I think you cracked the LPM market...:D

Jerry
Click to expand...

Well, not quite. We still don't know what's in the secret black sauce ;)

(although I swear to god I think it's just BBQ paint!)

In all seriousness though Jerry, I feel like you usually give my more flak ;p I don't know much about this product, so it's highly possible that my idea is flawed.
 
lasersbee

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rhd said:
Well, not quite. We still don't know what's in the secret black sauce

(although I swear to god I think it's just BBQ paint!)

In all seriousness though Jerry, I feel like you usually give my more flak ;p I don't know much about this product, so it's highly possible that my idea is flawed.
Click to expand...

It's not flak.... I just found it funny that no one ever though of
using a thermometer to make a highly accurate cheap LPM...:crackup:

Actually 2 degree accuracy would probably be ~200mW to 400mW
if not more...

That DX item is a thermometer...

It could probably be used as a rough measurement for Higher
powered Lasers in the multi watt ranges... but would still (as
you say) need to be calibrated but would still have low resolution.

I've seen old Dial type LPMs that are used for very high output
powered Lasers that seem to be Large Dial Thermometers like
you would use in the kitchen to see if your chicken is done...


Jerry
 
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Trevor

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Hmm, interesting.

I've been contemplating an open-source LPM to add a new dimension to the hobbyist LPM community. I have no interest in delivering a product, but I'd really like to see some meaningful development happen, especially in the realm of intelligence. I've just not had the time to devote to it. :(

I'd be curious to take one of these apart to see what's in it - might be of use. :D

-Trevor
 
benmwv

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Well I'm not saying this makes it capable of being an lpm, but the resolution is .25c. The accuracy is 2c but I don't think this will really matter once it is calibrated, as this probably means each one is consistently off by an amount no more than 2 degrees.

Just how I understood it at least.
 
rhd

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I suppose the implications of that 2 degree accuracy depend largely on how much temperate increase is caused by each mW.

If 100mW can only raise the temperature by 5 degrees, then the accuracy would be very poor. But if 100mW could raise the temperature by more like 30 or 40, then you'd be looking at a +/- of 5%, which isn't too bad at all. It also occurred to me that the accuracy might not be a consistent 2 degrees +/- throughout that whole 0-700 range. It might be (EDIT: "better") at the low end.

I suppose this requires some more thorough understanding of heat transfer from laser beams.
 
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L

LSRFAQ

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How about a real data logger..

Dataq's DI series. The +/- 10V input is easily modified or rescaled.

29$ and the software is excellent. Designed near my home town.

10 bits is not bad if your just trying to measure battery draw down or watch laser drift.

Data Acquisition Starter Kits

Any number of meter designs have been posted.

Steve
 
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Kmor2004

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The black box..me thinks is a serial to usb chip, some passive, and a micro, or just an ADC, and that's it, since micros are less expensive and take up less space then having to design a circuit using a bunch of active and passive components, and if you find a way o improve the systems its a simple as updating the software rather then finding parts at a good price and possibly having to redesign a PCB and re-running tests and having new boards made up.

With a lot of people (at least it seems that way) wanting to and actually making LPM's, actually making one that data-logs could actually be made for probably $50 ( dork-bot board/uC/op-amp/serial to usb chip) the biggest cost though is still a TEC, the bigger cost for the entire thing would actually be writing to software interface from the sensor to the PC or MAC.
 
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Trevor

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Kmor2004 said:
the bigger cost for the entire thing would actually be writing to software interface from the sensor to the PC or MAC.
Click to expand...

For Windows users, I can just modify Luminosity 1.5 for use with a new platform, no problem at all.

For Mac... maybe someone who knows something about Java? ><

-Trevor
 
rhd

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Does an LPM need to be MAC compatible? Aren't most MAC users accustomed to running VMWare or Parallels whenever they need to use real software?
 
Trevor

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rhd said:
Does an LPM need to be MAC compatible? Aren't most MAC users accustomed to running VMWare or Parallels whenever they need to use real software?
Click to expand...

Fair enough. Either way, you can count on software from me - firmware too if it's needed. :)

-Trevor
 
Guyfromhe

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I don't know anything about LPMs so this could be a retarded question but could you not use a photocell and a multimeter?
 
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