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DIY Power Meter

knimrod

knimrod

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I built this thermal energy meter for less than $50.00.  It has a range of 0-1999mW and sensitive enough to register a cheap 5mW red pointer.  The thermopile head is capable of much higher power. The 1999mW limit is imposed by the digital panel meter display.

It's powered by two 9 volt batteries and the amplifier is my own design (though it's pretty straight forward).  The switch is an on/off switch and the knob is an offset/zero control.  The digital panel meter could be substituted with a generic multimeter to save even more money.  The rest of the parts are readily available.  It's easy enough to build that anyone who can proficiently solder and construct a breadboard current regulator should be able to tackle this.  If there is enough interest, I'll document the build-up for other DIY'ers.
 





i'd be very interested in this :) Power meters usually are on the expensive side....
 
I'd be interested in schematic/ circuit diagram / parts list...
I'd be VERY interested! please post asap! :) (as I have just got the same Coherent meter board / head as you have from Kenom...)
 
Yes...Please do post parts list and circuit!

THANK YOU..THANK YOU..THANK YOU!!!!

Larry
 
Okay..  I'll start a build thread in the Experiments and mods section this weekend.  Please let me reserve the first 3 posts in that thread.
 
Many thanks for doing this. :D I already know what my next project will be. [smiley=evil.gif]

This hobby is not getting too far without a meter, just can’t justified spending $200 on a meter that does one thing.

I would like to know will it have the capability for different wave length. ::)

Regards,
 
Excellent, please document how to do this!! It would be something I'd build.

My only question is how you initially calibrate it.
 
Since this power meter is a thermal energy meter, the measurement is wavelength independent.  

I'm not 100% sure yet on the calibration but I believe that the sensor itself has a calibrated output so setting the gain of the amp to a fixed level should get you pretty close.  There is a gain control trimpot in the design and presetting it to a fixed resistance will probably work.  I only have a sample of 1 to go from at this point but so far, it's been predictable.  I calibrated mine against a known good meter but that means my calibration is only as good as that meter.  After a few of you have built this, I guess we'll find out how close it is.
 
Damn if this isn't the most useful place for a laser hobbyist on the web! :D

I'd love to tackle this as well. Once we get a parts list would anyone like to start a group buy for the component package? Maybe mark each one up $10 for time & trouble? It's been so long since I soldered something I wouldn't know where the hell to go for parts now, (Radio Shack?) so I, for one would be happy to compensate somebody with better access to parts.

Thanks for a great idea Knimrod!

Cheers, CC
 
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