DIY Laser Power Meter Interface Module

[positron]

You guys do know you can measure millivolts with your sound card, and there is free software out there to do this AND log the result?? d'oh.

It's like, uhh, maybe i should invent a tank that runs on egg yolk, so i can drive around, cos cars sure don't exist!

can a sound card measure DC volts? maybe you have to remove a cap on the input to the soundcard for that.

 

[woop]

there are definately caps in the way. you would need to either modify the sound card or turn the signal into AC its cheaper and easier to use a small cheap all one microcontroller

 

[knimrod]

BAHAHAHA XD
this is funny1!!
...

you're not serious...

You are serious?! You actually did this??
wow. there are some dense people here.

[quote author=BlueFusion link=1203305181/60#63 date=1205060896]You guys do know you can measure millivolts with your sound card, and there is free software out there to do this AND log the result?? d'oh.

It's like, uhh, maybe i should invent a tank that runs on egg yolk, so i can drive around, cos cars sure don't exist!

can a sound card measure DC volts? maybe you have to remove a cap on the input to the soundcard for that.[/quote]

No, a typical sound card can not measure DC volts.. At least not without modifications... Sound cards use series capacitors in the signal path to specifically block any DC current.

The overt and seemingly authoritative claim that a sound card would work in this application serves as good example to the notion that a little knowledge can be a dangerous thing.  The fact that the claim was made in such a rude and demeaning manner demonstrates the maturity (or lack thereof) of the claim's author.  Blue, grow up some more and then come back.. okay?

Sometimes, when all you have is 2 cents, you should just buy a stick of gum.

 

[amkdeath]

Sometimes, when all you have is 2 cents, you should just buy a stick of gum.

;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D


since when do people sell gum in sticks?


I mean, if your REALLY badly against buying an interface module, there is always this:
http://www.drillspot.com/products/112745/Fluke_189_True_Rms_Data_Logging_Multimeter

regards,

amk

 

[MarioMaster]

;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D


since when do people sell gum in sticks?


I mean, if your REALLY badly against buying an interface module, there is always this:
http://www.drillspot.com/products/112745/Fluke_189_True_Rms_Data_Logging_Multimeter

regards,

amk

you've never heard the term "stick of gum"?

 

[amkdeath]

[quote author=amkdeath link=1203305181/60#67 date=1205082065]

;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D


since when do people sell gum in sticks?


I mean, if your REALLY badly against buying an interface module, there is always this:
http://www.drillspot.com/products/112745/Fluke_189_True_Rms_Data_Logging_Multimeter

regards,

amk

you've never heard the term "stick of gum"?

[/quote]


do you read??? I SAID, SINCE WHEN DO PPL SELL GUN IN STICKS!!!

gum is sold in packs of 5-10 sticks. show me one quickie mart who sells a stick of gum for 2c

 

[LarryQ]

Hey Knimrod.....

I got my kit....REALLY NICE!!!!!

I plan on building it tomorrow....

I did notice that you suggest dropping the diodes since the PIC has the circuit built in....

Good Catch!!!!

I was wondering....I plan on "Tapping In" at my LCD panel input for the signal.....

This will give me the LCD meter AND a PC Interface..

Is there any potential problem using the same tap point for both the LCD and PC Output?

LarryQ

 

[knimrod]

Hey Knimrod.....

I got my kit....REALLY NICE!!!!!

I plan on building it tomorrow....

I did notice that you suggest dropping the diodes since the PIC has the circuit built in....

Good Catch!!!!

I was wondering....I plan on "Tapping In" at my LCD panel input for the signal.....

This will give me the LCD meter AND a PC Interface..

Is there any potential problem using the same tap point for both the LCD and PC Output?

LarryQ

Thank you!

The diodes were something I always do with direct processor inputs but I guess I didn't do my research well enough.  I should have known since most modern microcontrollers are well protected.

You can use the amp output to drive the interface and the DPM, no problem.  That's what I did.

I also recommend installing the extra cap I included in the kit, on the amp PCB as indicated in a previous post.  

 

[knimrod]

I just put version 1.2 of the interface software up and it's available for download here.

In this version there are some changes to the congiguration settings and the addition of a basic graphing function.  It's not a live graph but rather a way to graph a previously saved log file.  Data logging to a file can store up to an  hours worth of data.  The graph can display both channels if there is valid second channel data in the log file.  In the picture below, the second channel log data was disabled by setting the gain to 0.  If it was configured for the optional current measurement, I could have set the 2nd channel units to mA with the appropriate gain value and the graph would have also displayed the current in blue and its corresponding ticks/scale on the right.

It may be a little buggy but it's been working okay for me so far.  Let me know if you encounter any problems.

 

[LarryQ]

Hey Knimrod.

It Lives!!!

At first I thought I had something wrong.

I could not get a handshake on my PC...
Easy fix....I had another program tied to Com1 that I completely forgot was running in the background.

As soon as I closed that program, your software lit right off!

I'm now in the process of stuffing everything back into the project box.

It's going to be tight...but it SHOULD all fit.

So.....what else have you got up your sleeve??

Don't let my soldering iron start feeling neglected!

LarryQ

 

[Archane]

I'm in for one of these

i'm waiting for other people to order the controller board you mapped out from the other thread so I can get that since I joined this late.

 

[dar303]

Damn! I forgot about this and missed it!
Count me in for one in the second run!

 

[Dark_Horse]

I just finished the LPM, super-cool project, thank you Knimrod, I could not have done anything like this without you and the rest of the brains on this forum, I will post pics later, but I am ready for the interface module.
If you make another run of boards/kits, I am definietly in for (1).
Thanks Again,
Dark Horse

 

[amkdeath]

ok, I really do have the money this time, count me in. I need one.

 

[jake21]

count me in to

 

[knimrod]

I've updated the third post in this thread with the group buy details and status.

Archane and Jake21: I did not add you yet because I wanted to make sure you understand that this group buy is only for the interface module kit and not the DIY Amp.  If you still want in on the interface module kit, let me know.