strain sensor and associated electronics

Public Clarification Board

Sharing of contact details is prohibited by the Terms of Service.

Post Message

• 

  TopGunPk

  Hello Vadim.
  
  If you are going for the DAQ boards, do selet ones that support Bridge meaurments, specially fom Strain Gauges / Load cells.
  
  I had used Keithley Metrabyte's systems a few years ago, but ofcourse we didnt have LabView's products soo widespread then. I believe LabView and its associated products could give you a good head-start.
  
  In case of any problems, please feel free to ask anything.
  
  Happy testing :)
  
  Warm Regards...
  Zeeshan A. Noorwala
  Automation Engineering Solutions

  Attachment: DB1.MDB

  over 1 year ago

• 

  DonastiaIP

  Based on all of your questions, I have come to realize that the project parameters were not adequately defined for board development. I am getting several different gauges, a regulated power supply, and a daq board.
  
  Current plans are to use a full bridge with a 1.5 volt excitation voltage.
  
  I expect that I will have answers to everyone's questions before the end of the month. If you have questions you need answered to define a bid, let me know. I apologize for any inconvenience.
  
  Vadim

  over 1 year ago

• 

  TopGunPk

  Hello DonastiaIP.
  
  This is Zeeshan from Automation Enngineering Solutions. WE design custom embedded, control systems and precision Test & Measurment equipment, specifically for the Pharmaceutical and Food industries.
  
  WE have had considerable experiance with Strain gauges as well as their cousins, Load cells in some of our designs.
  
  There are several things you may need to know before you can delve into this project.
  
  First of all, your required 60Hz range is no problem from a systems designer point of view, BUT, a good practice in most data-acquisition systems is to select a measuring frequency either much less than that, OR higher than that. The reason for this is that most of the times the signals recieved have a ~60Hz noise superimposed on them from nearby electrical power cables. Hence the circuitry needs to eliminate this by adding either Low-pass or High-pass filters.
  
  Secondly, in my humble opinion, Strain gauges / Load cells are beautifull pieces of artwork rather than scientific elements, and hence need a lot of care, both during designing as well as during use.
  Sice i am concerened with designing initially, i'd like to know certain parameters so i can formulate a design.
  
  The mV/V is a fancy term meaning that the maximum output of the gauge (at max. pressure applied) will be this mV/V value X total input voltage.
  
  For Example, if the mV/V = 3mV, and you excite your load cell with say 9V, then at the maximum range of pressure applied, the output from the load cell will be 3mV X 9V = 18mV total.
  
  This gives us the upper limit to measure, and hence design the circuitry according to it.
  
  As far as your 2-digit display is cocnerned, my colleague Stefan is absolutely right, there is no way you can display all that data on 2 digit. However, you may make an arbitrary scale for your application, and the contorller can convert the readings from the gauge into these units and display on your 2-digits.
  
  For example, lets say we have a Load cell that has a measuring range of 0 to 15 KG. You can convert this to a cale of 0 to 45 and the firmware running in the controller will be able to give u the display in your scale units.
  
  We can design on Constant Current (CC) as well as Constant Voltage, it depends on the application and useage of the gauge.
  
  The excitation voltage limit varies with manufacturer to manufacturer, as well as with differt models and ranges, but for your application, i believe the strain gauge can handle upto about 10V. Yes you can go to minimum 1.5V also (as per Omega tech support) but we will select the best possible value once we get down to the designing.
  
  WEll.. i believe the strain gauge you are getting has a wire / cable attached to it, so that will be your preffered method of attachment. But we'd liek to know how many wires there are, 4 or 6 (or 8)?
  
  I am not bidding on this project just now. Once all the figures are confirmed, then we may make a suitable bid.
  
  If you are interseted in developig the system at your end, then we can provide the following services :
  
  a) Strain gauge Signal conditioner design,
  b) microcontroller system design,
  c) Firmware design and functional testing (on a prototype we build),
  d) Schematics, PCB layout and BOM,
  e) all Electrical, QC and functional checks.
  
  If you want finished prototypes / systems, do let us know and we can offer our prices.
  
  Warm regards...
  Zeeshan A. Noorwala
  Automation Engineering Solutions
  
  
  
  SGD-3/350-RY13

  over 1 year ago

• 

  DonastiaIP

  Stefan,
  Thank you for your response. As you can tell, I have had limited contact with strain gauges. The application here is to put the strain gauge onto a tuning fork to quantify the amplitude of its oscillations. The goal here is to create a portable electronic device. Please see below for specific responses to your inquiries.
  
  C:For your needs you have to get a strain gauge calibrator which uses instrumental amplifier with half bridge input.
  --> is this required because of the temperature problems with strain gauges, or for another reason??
  
  Q:Which is your resistance and mV/V sensibility interval which you expect?
  --> I have no idea.
  --> the strain gauges I would like to use are Omega Supply part no. sgd-3-350-ly13
  
  C:The device will work with CC excitation voltage.
  --> what do you mean by CC??
  
  Q:Which is the excitation voltage limit which you expect this strain gauge to work?
  --> when I spoke to the techinician at Omega, he said that he has seen applications where 1.5 volts is sufficient for these gauges. Does your -->experience tell you otherwise?
  
  C:Regarding to a small volume of the device,it can't be done because you need a step-up converter to generate the excitation voltage and extract high quality selection parameters of the gauge.
  The 2 digits aren't enough to display the data.
  --> I am not looking for absolute strain data. I would like to display the measured strains on a scale of 1-50 on the screen.
  
  Q:Regarding the connecting way of the gauges,which is your suggestion?(by wire/direct connection...).
  
  --> by wire.
  If you are interested only in direct gauge resistance,this parameter is not edifying for selecting.There are ASTM procedures used for this kind of tests.
  
  Please see my work at w w w (dot) jsindustries (dot) ro, in the Software Design/SplitMonitor section you will find a kind of project regarding your request.
  
  Regards,
  Stefan

  over 1 year ago

• 

  jsidev

  Mr Vadim,
  My name is Stefan and I have degree in physics and electronics and I worked more than 15 years
  in thermo-mechanical research and simulation.I am working on many projects with strain gauge and
  specialized equipment for strain gauge bridge measurements.
  Related to your project requirements I have a few questions and comments:
  
  C:For your needs you have to get a strain gauge calibrator which uses instrumental amplifier with half bridge input.
  
  Q:Which is your resistance and mV/V sensibility interval which you expect?
  
  C:The device will work with CC excitation voltage.
  
  Q:Which is the excitation voltage limit which you expect this strain gauge to work?
  
  C:Regarding to a small volume of the device,it can't be done because you need a step-up converter to generate the excitation voltage and extract high quality selection parameters of the gauge.
  The 2 digits aren't enough to display the data.
  
  Q:Regarding the connecting way of the gauges,which is your suggestion?(by wire/direct connection...).
  If you are interested only in direct gauge resistance,this parameter is not edifying for selecting.There are ASTM procedures used for this kind of tests.
  
  Please see my work at w w w (dot) jsindustries (dot) ro, in the Software Design/SplitMonitor section you will find a kind of project regarding your request.
  
  Regards,
  Stefan

  over 1 year ago

• 

  amitj9

  Hi,
  Please find attached my CV
  Thanks

  Attachment: amt_reslatest_cons.doc

  over 1 year ago

Show more messages