Kegerator scale using the Moteino Node Network

Started by jdolsen, May 11, 2015, 06:11:46 PM

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jdolsen

May 11, 2015, 06:11:46 PM
I just completed my first project using the Moteino Node Network (https://lowpowerlab.com/forum/index.php/topic,1072.0.html)

I wanted a keg scale to keep track of how much beer is left in my kegerator.  And I wanted the scale to notify me when the keg is nearing empty (time to brew again!).  The Moteino in this project reads the voltage provided by a load cell-instrumentation amplifier circuit, converts it to a weight and sends it to the MNN host.  When the keg is nearing empty, the host sends a text to my cell phone!

  I got the load cell from Amazon (http://www.amazon.com/gp/product/B00NH9Q9LK/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1).

Circuit design, Circuit calibration, and physical assembly took about a day once I had all the parts.  The Arduino code using the MNN libraries made programming and network integration quick and easy (a few hours).  I've included photos of the result.

Now that testing is complete, I just have to paint, install, and get to work on my next project.

Felix

#2
May 12, 2015, 08:30:48 AM
Very nice, thanks for sharing, any other photos?  ;D

TomWS

#4
May 12, 2015, 05:24:36 PM
Fun!  But when do we get to sample the beer?

8)

I haven't worked with load cells before and was surprised how relatively inexpensive it was.  I'm also surprised by the measurement axis/plane.  Does it measure the compression on the two side pillars or flex of the thinner center section?

Tom

jdolsen

#5
May 12, 2015, 05:48:48 PM
That's a good question Tom.  In fact, I had the same question before I ordered it!  This style of load cell is connected at the two ends.  One end connects to the bottom plate and the other to the top.  The middle of the cell is the only thing that links the two plates so a force applied to the top plate will flex the middle of the cell.  The one I used is a resistive binocular dual beam load cell.  Have a look here for more information:

http://www.sensorland.com/HowPage005.html

This is pretty good too:
http://www.rdpe.com/ex/hiw-sglc.htm

jdolsen

#6
May 12, 2015, 05:57:29 PM
Let's never have this happen again... ;)

TomWS

#7
May 12, 2015, 07:03:26 PM
Quote from: jdolsen on May 12, 2015, 05:57:29 PM
Let's never have this happen again... ;)
It took me a while to figure out what I was looking at.  NOW I understand!  No, one should never have a tap run dry.  In the old days, I'd only have one glass of beer a night.  Of course, I'd never let that glass go empty...

Tom

jdolsen

#8
May 12, 2015, 08:47:01 PM
;).  You won't need to turn your head to view this picture:
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