Force Gauge

cjkogan111

Hello,
I work for a high altitude ballooning group - we are interested in measuring the force between the payload and the balloon (maybe 5-10 times a second) for the duration of a flight using the basic stamp & then some type of data storage such as some EEPROMs. Has anyone come across any writeups in the completed projects forum, or anywhere else that has relevant information. I would be interested to hear what instruments/gadgets other people have used to measure force, and how they have hooked them up to the basic stamp & collected data.
Thanks!
-cjkogan111

Phil Pilgrim (PhiPi)

Look up "tension load cell" on Google.

-Phil

cjkogan111

Hi Phil,
Tension load cells tend to be a bit pricey - $500+
I was looking for something under $100.

Also, if anyone has ideas about the data acquisition options, I would be interested.
Thanks!
-cjkogan111

ellizard

HI cjkogan111,

have a look here: www.parallax.com/detail.asp?product_id=30056

Just a suggestion

Stefano

LSB

Or, use an accelerometer and interpolate from a known module weight...

Phil Pilgrim (PhiPi)

Perhaps you could hack a cheap digital fish scale: www.berkley-fishing.com/prod.php?k=50540&sk=0&p=PURFS30

-Phil

Martin Hebel

DigiKey has a number of load cells under $100, I've used a number in my courses. Most take a 5V supply and have a very linear output. You'll need an ADC to read them. The 'figure 4' on this page would meet your need best as it can be used to measure pulling force - $55, in a variety of ranges.
http://dkc3.digikey.com/PDF/T072/P2119.pdf

-Martin

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StampPlot - GUI and Plotting, and XBee Wireless Adapters
Southern Illinois University Carbondale, Electronic Systems Technologies

Post Edited (Martin Hebel) : 5/29/2007 6:34:05 PM GMT

cjkogan111

Thanks guys,

Stefano - Is there any way to hook thing up easily so that I can measure tension with that device.

LSB - I will look into the accelerometer - thats a good idea.

Phil - Do you have any ideas about hooking the fish scale into a stamp?

Martin - Those parts look good, but do you know if they have a specs sheet? That link is just a catalog page, and it is hard to really know what you are buying until you get it.

Also, does anyone think that this strain gauge could work: http://www.vishay.com/docs/11305/500bh.pdf

Thanks again,
-cjkogan111

Martin Hebel

Goto www.digikey.com and type in the digikey part number of the one you are interested in. Follow the links they provide and it will give you the data sheets. It hard to link directly to digikey search pages.

-Martin

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StampPlot - GUI and Plotting, and XBee Wireless Adapters
Southern Illinois University Carbondale, Electronic Systems Technologies

LSB

Obviously, you'll want to check the lower temperature limit of operation and the linearity as affected by any kind of heating you may employ. My thoughts in recommending the accelerometer were the extreme environment, weight, and sheilding the sensor inside the module. Also, a 3D module would describe turbulance, radial stress (spin), and negative gravity as well.

Parallax sells a 3D-3G model (may be enough (?) as the balloon will soften shock) --completely and expertly documented. Also EEprom, of which you will likely need plenty!

Post Edited (LSB) : 5/30/2007 12:56:17 PM GMT