@harashri You can use the Load Cell Shield with the Arduino UNO and two load cells for example to measure the weight of the luggage. You can also use a Bluetooth Shield stacked on top of the Load Cell Shield which will send the weight measurements to your Android device via Bluetooth.
Hi there, Iām using a Novatech loadcell that can be excited with a 10 V - 20 V range, which Iām presuming is beyond what the Arduino/RB-Onl-38 can provide, if I use a 12 V dc power supply and connect the ground pin to the Arduino board, will I still be able to use the RB-Onl-38 boards? Thanks
@Sean Yes you can supply power to your load cell separately from the RB-Onl-38 by connecting the red wire of your load cell to Vcc (+12V) and black wire to GND of the Arduino/RB-Onl-38
Thank you Brahim, now I apologise and I realise this must be a rather stupid question but I am rather new to Arduino and programming. You include an zip file with example codes, but what ones do I open exactly and which parts do I need to change for the calibration and finally how do I integrate the code into my existing code.
Hi Brahim, is there perhaps a way to contact you directlyā¦?
In answer to my earlier question I found the sample code on the purchasing website, where you apply 2 loads and interpolate between them,
Just when I run this code I get a 0 output, my strain gauge is 2.5 kN, with a bridge resistance of 700 ohm, my question then is this compatible as usually you have to balance the bridge.
@Sean We unfortunately donāt offer consulting services. You can post your question on the RobotShop Forum to have the RobotShopās community input or contact us on the Support Center if you encounter a technical issue with the Shield. This being said, an Arduino Library is available for this Shield with comments to understand how the code works and how the calibration is done. This is a great article that explains how to wire a Wheatstone Quarter Bridge for your Strain Gauge.
I am using a 100g load cell to measure about 30g and want to increase the sensitivity around that point to get the best resolution to small changes around that point. I changed the reference voltage but it seemed to just raise the increase the no-load reading. The documentation references an external gain resistor. How is this connected? I want to use a potentiometer at lesast initially. What would you suggest?
@Steve The default gain on the Load Cell Shield is 495 for each channel (Strain1 & Strain2). This is set by the resistors (100 Ohm each) next to each connector on the board. The SMD gain resistors can be replaced to increase the gain. You can take a look at the resistors gain table in the AD8426 Datasheet. You can also increase the resolution by connecting the 3.3V pin to the Aref pin on the Arduino and use the analog reference external function. Also, the Arduino boards do not include a decoupling capacitor on the AREF pin, so we suggest that you add one when you connect it to the 3.3 V DC source to ensure maximum accuracy and attenuate any high-frequency noise.
Hey! Iām working on a project titled as Coin Sorting Machine. I need help. Please tell me about how to interface a load cell(600g) to the Atmega16 IDE board.
@Akshay The ATmega16 has an 8 channel 10-bit ADC, therefore, you can use your 600g load cell interfaced with the RB-Onl-38.
Hello!! First, I would like to say great thread of questions and response, very informative. I am working on a project and itās my first time working with load cells; although not my first time interpreting resistance/voltage based sensors with analog input. I had originally planned on just using an INA125 instrumentation amplifier but as a matter of convenience I am contemplating working with the load cell amplifier shield, Iām pretty sure I already know the answer to my question however, I plan to provide voltage to the sensors externally as they operate on 10/15V DCā¦I know kind of odd, however I canāt find a data sheet I have only been provided with testing data from the sensor manufacturer. As long as I establish a common ground, do you feel I would have any issues just channeling the sense lines through the shield. In theory I donāt see an issue with this as long as amplifier, sensor voltage supply and Arduino have a common ground I just figured I would check with the experts whom have more experience with this shield than I. Thank you for taking the time to review my question and provide a response.
@Tank Thank you for reading and for the nice feedback. If your load cells are rated for 10V-15V, you can certainly power them externally by providing 10V-15V between the red and black wire. The black wire should be also connected to the GND of the shield which is also connected to the Arduino GND. The sense lines (green and white wires) will be connected to the Strain connector on the shield. However, please note that the supply pins of the amplifier on the shield is internally connected to the 3.3V from the Arduino. Therefore, even if you power your load cell with external supply (10V-15V), you still have a range of 0V to 3.3V on the output of the amplifier. The total analog voltage output from the shield will vary in a range of 1.25V within 0V-3.3V. This is due to the on-board low pass 2nd order Bassel filter.
Hi, I want to use the load cell to detect when my beer keg is getting empty :-)ā¦ But that will mean that the cell is under load all of the time. I read something in one of the comments that listed ācreepingā when under constant load. Would this be an issue for my use? Thanks,
how to connect load cell with raspberry pi3(load cell has only tx pin)
@Phil The creep is usually expressed in units of % of the full scale (capacity of the load cell) over a period of time. Therefore, the creep variation will be important (will have more effect) if you choose a load cell with a capacity near to your full load which is, in your case, a fully loaded beer keg. For example, this 5 Kg Micro Load Cell has a creep of 0.1%FS per 30 minutes. This means that after 30 minutes, this load cell will be outputting : Its rated output Ā± Error + 0.1% x its rated output = 1mV/V Ā± 0.15mV/V + 0.001mV/V = 1.001mV/VĀ± 0.15mV/V. In this case, choosing a load cell that has a capacity higher than the weight of a full loaded beer keg, will decrease the effect of creeping but not too much high as this will also lead to a loss of resolution.
When the program is running, what units are the read-outs in? And what is the best way to calibrate it to SI Units?
@LJ The actual example from the Arduino Library of RB-Onl-38 outputs the ADC Raw value and the force in grams. You can convert the RAW ADC value in the calibration to any unit you want.
@Brahim Daouas can you tell me how to calibrate two connected three wired load cells using arduino.
Thanks 
@Dixit Calibration of 3 wires load cells is the same as 4 wires. It is done in the Arduino example provided in the user manual in the documentations or in the Arduino Library. It is explained in the comments.