There are a number of companies in the universe that make PCB boards. Force load cells and torque load cells share the same measurement principle, so you only need to buy a torsional load cell, or to exploit a cantilevered shaft in order to load a force load cell from a torque. Or have I totally missed something!? A strain gauge is a component that is used to measure strain. Your choice is really good for high precision measurements since noise plays a relevant role into determining resolution (and accuracy as well). If you wire the thing in a good manner you get really accurate noiseless signal conditioning In the case I have more than one ckt, how do you suggest me to calibrate G tho be equal in each ckt? In the setup section, first, we started the serial monitor, this is just for debugging only. Just connect the analog port of the PLC to the circuit output S1. So I used 20 Ohms as gain resistor (two 10 ohm resistors in series) and suddenly the voltage, without any load applied - starts at 1.0 Volts and with 100 grams load it is at 3.8 Volts . up to 5000 The current flow generates heat in strain gages and sadly those components suffer temperature drift. My long term challenge is, that id like to dispense a set amount of powder, around say 30 grains , once the desired weight is reached the dispenser would stop. This is easily achieved by moving the wire of the INA125 from pin 14 to pin 15. HX711 module is a Load Cell Amplifier breakout board for the HX711 IC that allows you to easily read load cells to measure weight. Nov 23, 2020 Exactly, the problem was the power supply, it must be symmetric, if not, data lower 200 mV are unread. I'm glad for your appreciation! thank you. Can you please email the Gerber files to me? In fact, no matter how good your setup is, every transducer suffer from uncorrelated and correlated noise. And how i can assembly all component to make great laboratory weight scale. we used a round plastic sheet as the top smart of balance. How would you recommend building a project like this? What you have to do, if you want the circuit to behave like you said, is to provide a +5V and a -5V power supply and wire the circuit in the regular way, as shown in figure 1, page 10. Looking for an HX711 ADC alternative. My wiring is like this (but i use Arduino mini pro 3V3): Apparently it should be a full-bridge circuit where the temperature is fully compensated and … We used female headers to solder the Arduino and ADC with the circuit board, also we have used wires to connect all the pushbuttons and LEDs. The pot sets up the behaviour of our amplifier, so altering the pot means changing radically the response of the circuit. 1) select an accurate load cell (something like this ). If the answer is "yes" you'd better go further with reading this. In the circuit shown in figure 5, the gain also alters the zero level. Required fields are marked *. Another question about gain resistance of 10k ohm/10 turns Email :, Thank you Alberto for this tutorial Then upload the code to Arduino and open the serial monitor. One more thing alberto, If i need a VREF 10V I need to supply the INA125 with a symmetrical voltage source of +-15v? Article finally finished (I apologize for delays) with video too. At zero load the circuit will output 2.5 V. If the load is positive, voltage output will increase. published online and programs... Presenting the OSHap at the 10th IEEE/ASME M.E.S.A conference, Power up a full bridge strain gage load cell (the 4 wires-one), Providing the possibility to change continuously the gain within the range, 5V power supply (since current drain is really low, every supply is good. Now, we need to place the known weight on the balance, in my case, that is 194gm. Thanks, Ben. It states that this is the power supply for my load cell but I measured the "+1" output to be 2.5V. can you suggest an alternative? Nonetheless the preload strain (which is the strain caused by the classic strain gage glueing) is also a limit. If you are working with digital system, go for a FIR lowpass filter (such as mobile average) or a IIR buttherworth or chebyshev filter. In the end, you will retrieve a table similar to the following one (coming from a calibration of a 5kg Phidgets load cell): Now, we got to estimate the correct linear law that converts kilograms into voltage, in the form of: where V_0 is the output at zero load, G_S is the circuit sensitivity and W_L the load applied. ¶ Connect GND to GND , VCC to 3.3V and the other three MISO (or SO for short), CS and CLOCK (or SCK ) … I think this will work. Thanks man, nice explanation. That is, in the beginning, the display shows ARDUINO BALANCE as welcome text, and after two seconds, it will clear and display the measuring weights. for a calibration setup is it reasonable to simply place/stack this cell on top of a good electronic scale and apply forces to the cell ? It is possible to get this values with this application that you manage? Dear Rodrigo, My question is; First, we need to calibrate the load cell and store that value on EEPROM, for that, go to file > examples > HX 711_ADC, then select the calibration code. The function increasing the set value by 10gms for each press. At this point you should see the signal beating together with your finger on Test-Panels. Why is pin 5 connected to 4 and not to 3 instead? checkdown is for decreasing the set value by 10gms for each press. I've bought a 0-300 grams load cell from eBay (i want to be able to weigh max. Indeed the best option, once you have defined a good amp gain, is to replace the potentiometer with a fixed resistor. HX711 on breakout board - This microchip is specially made for amplifying the signals from load cells and reporting them to another mircocontroller. So you should not exceed it in order to operate your load cell in "safe mode". To perform linear regression you may choose between thousands of methods, you can even do it by yourself with calculator. Now if we increase the area, it will increase the resistance of a conductor. As you can see, one side is marked with ten kilograms. Let me say that they are two different things: INA125P is a mid-to-high end analog instrumentation amplifier while HX711 is a strain gage load cell digital interface IC purposely made for consumer electronic (let me say it's made to equip the standard kitchen scale or … Now the second thing you have to do is to regulate the circuit gain and reach the desired level of amplification. Hello,I have used ur circuit with 22k pot and cannot get load cell calibrated correctly.Why?? sir, Use the Analog Inputs. Shouldnt it be at the VREF voltage? How to get out of such a mess? In this case by plugging Ia_ref pin in the power supply pin you make the IC believe that the ground is 2.5V (so called pseudogrounding operation). Load cell wires hooked up to the HX711 Amplifier board Once the load cell is is hooked up to the amplifier, you can hook up VDD, VCC, DAT, CLK, and GND to a microcontroller such as a RedBoard or Arduino board. If you have run calibration the way I explained, it may be common to have a zero load output different to zero (this is due to the fact you are estimating statistically the zero load output). The core of this project is a wonderful and flexible Wheatstone bridge amplifier IC called INA 125 P made by Burr Brown - Texas Instruments. Check these out: I am using a Z. Thank you for this. Could you explain me how you got the formula (it's for my degree project, this week) Follow @lelliollo I've build your circuit on a breadboard and it works perfectly. Would it be possible to be emailed the Gerber files and the schematic of the circuit? So my question is: Why does increasing the gain resistor also increase the no-load voltage? If you are interested I will email them for free. If we stretch the strain gauge, the resistance will increase and if we compress it, the resistance will get lower. Cons: Congratulations for you amazing tutorial. You need to digitalize the data and this is not trivial. Set weight is setting with the help of the Pushbutton counter. sir which software use for simulation for this project i? I designed this circuit for bidirectional sensing. Load cell and need measurement in both directions.I have fitted a switch to reverse polarity.Switch up when air ram pushes a car shock up and down when shock extends. We place the strain gauge in the Wheatstone bridge if the bridge is balanced, the voltage in the middle point should be zero (previously we have built a project where we have described how a Wheatstone bridge works, you can check that out if you want to know more about the topic). *Excitation(recommended)=10V to 12V DC thanks a lot for such a wonderful video. I reviewed your introduction information, you are impressive. Alberto, I appreciate it. 5kg load cell - Load cells are specially shaped metal parts that have strain gauges glue to them. -every measure should be FILTERED. 4) what is the weight level of your calibration? In order to post comments, please make sure JavaScript and Cookies are enabled, and reload the page. The fore mentioned block scheme is valid for both LabView and SignalExpress. The values which I read from my arduino's analog input are fluctuating pretty strong, e.g. The HX711 chip integrates a regulated power supply, an on-chip clock oscillator, and other peripheral circuits, which have the advantages of high integration, fast response, and strong anti-interference. The dynamic range of the full load cell is reduced. The load cell is a straight bar load cell … 3) you set a low level of gain with Rg, Hi Alberto, thanks for a great tutorial. This effect has the same magnitude of changes in resistance caused by strain and so this will cause a "ghost strain" that will hide your force reading. Should I leave this extra wire floating or should I connect it to ground? My current plan is to hook-up my load cell to a stand-alone instrumentation op-amp and funnel that into the ADC of my MCU. With help of the Arduino PULL UP function, we set the pins to a logical high at normally. I used ina128p, the load cell works well, it changes linearly with charge, but when it have one charge than less to 20 lbs the cell not measured, have a constant value. Then I could repeat the process with a push of a button. All the modules work on 5V, so we have added an LM7805 voltage regulator. I have tal220 10kg load cell that I using for an automatic dog feeder. Using PLC it may interesting but not necessary to power up the INA125P with higher voltage supply (let's say V++ equal to 9V instad of 5V). Thank you for this great blog. HX711 module is a Load Cell Amplifier breakout board for the HX711 IC that allows you to easily read load cells to measure weight. This module uses 24 high precision A/D converter chip HX711. But this voltage change is still very small, so to increase that, we need to use the HX711 module. What components you prefer to use ? In any case, by choosing a proper level of amplification, you may be satisfied with that, since measuring 0.1 grams out of 100 grams is not a high precision task for an INA125P (which I used for high precision tasks such as measuring 0.1 grams out of 1 kg). Hi Alberto, is there a replacement for an INA 125p? Dear Ben, For instance, a good practice when delaing with load cells is to use ADCs with high accuracy, so that you don't need to over amplify signal to read it correctly. -for relaxation the only solution is selecting a different load cell. You get the data already digitized. from ~105 to ~115 without load. thank you so much for for one of the most advanced tutorials on load cells. Or should I proceed in another way? Then change the baud rate to 572600. I never tested the Linx binding for Arduino, hence I'm not able to say if there is any particular limitation. To acquire data using National Instruments softwares you have a bunch of options: First of all, this is a wonderful tutorial, the best by far among all those available online for load cells. Like commercial products, our weight scale will have a zero button that zeroes out the scale. Subscribe below to receive most popular news, articles and DIY projects from Circuit Digest, The CR01005 chip resistor features a three-layer termination process with a nickel barrier. Now monitor ask to take the weight, for that we need to press t and enter. thanks for having appreciated this tutorial. We will be using a PVC board for the base of our scale, for that, we first cut 20*20 cm square and four 20*5 rectangles from the PVC board. Remember, we didn't fix one side, because we need to place the pushbuttons, LEDs, and the LCD on it. 2) is the INA125P working? HX711 is a 24-bit Differential ADC, in this way, we could measure very small voltage changes. It would be nice to know your opinion about this. My e-mail address:, am final year student of electrical engineering,My project is to design CNG and petrol indecator for fuel monetering i am use loadcell for petrol (resistive strain gauge ) and also load cell use for CNG ) with the help of Arduino and LCD display value in the form of digital ,Sir simulate this project by Proteus softweare or other softweare... i am wating. Once you connected your DAQ, you can go for the block scheme: If you don't want it as portable, you can directly power the Arduino using a USB cable. Are you really annoyed by the fact that force signal transduction costs more than the full robot control? hello Alberto Lavatelli.... Don't worry, I'm not in discomfort with giving advices We did that using if conditions, we have a total of three conditions. Also, you can notice some sort of white protective glue over the load cell and four different colors of wires are coming out, will uncover the secret underneath the white protective glue and the function of these four-color wires later in the article. It is simple, but selecting the right transducer (in this case I designed the transducer) it's an hard task. If you do travel to California (Los Angeles area) and would like, you could stay with my girlfriend & me, we have a guest room. Nonetheless, this module is commonly being used to measure weight. This is 99% accurate to original measurements. My advice, in this case, is to equip the free end of your load cell with a simple carbon fiber thin plate. 2. Inside this protective glue, we will find a very thin elastic component which is called a strain gauge. or it could be at +-10v.. +/- 10 V supply won't be enough and may burst your IC. The accuracy you need can be reached with a general purpose 16bit ADC, which is way cheaper. We can do this with help of the Wheatstone bridge. I'm using an Arduino 5V supply to the INA125, and a pot to balance out my bridge. First, we displayed the welcome text using the LCD.print() function, after two seconds, we cleared the display using lcd.clear(). What do you think ? I am building a product in which I am making bi-axial strain measurement would love to have your feedback on my project. Same goes when I apply load - it also seems like the voltage of the INA drops from time to time - e.g. Thanks. INA125P is simply a rail-to-rail differential instrumentation amplifier. So, this is how the Wheatstone bridge converts resistance variations to voltage values. I'm still waiting on the delivery of my 16 bit ADC from adafruit (ADS1115), that should be more than enough for my use case, according to your helpful formula. If my strain gage has recommended excitation 5-12V should I modify this amplifier? This week I'll graduate for my masters, then I will have time to upload a tutorial on fully symmetric wiring for the INA125P, forgive me I have more questions By connecting the amplifier to your microcontroller you will be able to read the changes in the resistance of the load cell, and with some calibration, you’ll be able to get very accurate weight measurements. The Load Cell Amplifier and ADC Module is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. I also want to record a height measurement along with the spring pressure. please give me answer? Alberto. Secondly, the real big problem is how to design a proper powder receptacle for your application. Sorry, but I find it hard to understand your English. Thanks Alberto, I will try the voltage divider. 3) do not raise too much the amplification, otherwise you will get saturation and noise problems, Let me know how it's going with your project, I have a 12V regulated power supply that I bought for the load cell, should I do away with the 12V power source and use the 5V from my DAQ to power my load cell? Finally, we will be building a portable Arduino-based load scale with the HX711 Weight Sensor, which can measure weights up to 10kg. This also brings up another concern: the circuit only works at its best when the bridge is balanced, but if i balance too far and hit negative differential voltage, then the Vout blows up. Now I don´t understand really well how i can get the 10v supply from the Ina128p because a measure the present value and i don't have any voltaje. interested people may contact us. The principal problem is that the circuit is not zero-balanced, this means that your Wheatstone bridge has not a zero level. You are at the right page :) This is 5kg load cell that comes with HX711 amplifier board. I'm considering building myself a small dynamometer, for testing fractional horsepower motors and drive electronics, so probably an electrically noisy environment, where a good front end is essential. This is normal, so, what you have to do is to: 1)filter the signal in order to remove noise. your situation can be generated by 3 different problems: also, we print the set weight. You can use it with all load cells available on the market. I realize this will affect my curve and will have to re-calibrate when the final resistor is placed. The Load Cell Amplifier is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. Next, we need to display the stored value in LCD. The 2.5v becomes 0.8v and the 3.3v becomes 1.4v (based on the max output of the INA being 4.2v). The load cell amplifier is based on the IC HX711 which is 24-bit analog to digital converter specifically designed for weight measures. *Output resistance=350ohm In my circuit, the output at zero load is 2.5 V (with 0.15 V tolerance) independently from gain settings. EEPROM is the inbuilt library of Arduino ide, which is used to store values in EEPROM and the LiquidCrystal library is for the l2C LCD Module. I'm a Ph.D student on civil engineering, so I'm not very used to this area. In fact with those ICs you can have the shortest possible measurement chain, which means the shortest possible noise coming from your circuit. First thing I'll invite you to take a look and download INA 125 P datasheet, since it will be useful later. The load cell is a straight bar load cell (sometimes called a strain gauge). This marks the end of the programming part. Understanding load cells is a matter of mechanical, electrical and electronical knowledge and it takes a lot of time (in fact now my job is teaching this at the university). I have a HX711 board on the way, for anyone who is interested in details on the HX711 the website I used was k means thousands (so 60k means 60000 Ohm). Thank you for appreciation. I am quite new into this topic but could you please send me the Gerber files, and also if you don't find it too hard to explain to me what does each of the components do in this circuit and why is it placed where it is. I suggest you to take a look. This module uses 24 high precision A/D converter chip HX711. I need to 19 ina125p at the same board and connect them to 10 strain gauge bridges. There are many tutorials on how to use a INA 125 P with load cells with Arduino,  but none of them really makes much sense. Do i need to use different potentiometer or capacitor? You said you used the INA125P to measure 0.1 grams out of 1 kg - what setup did you use to solve that task? Is this circuit use to measure torque of oscillation.. 100 grams, but with an accuracy of 0.1 grams), so I thought that this one is suitable for me. After all the soldering process is finished, we have made sure that proper 5V is coming out of the LM7805. But, before this, try with 3V and a good load cell. Well, you can use in your case the wiring configuration shown at page 12, figure 5 of INA 125 P datasheet. Where would I possibly have gone wrong? Alberto, I want to design a weight balance that have the capacity of 2000kg. (Don't forget that two wires connects only when you see the blue dot connecting them!). Other good suppliers may be Zemic or Stellartech for heavy duty tasks. The input circuit can be … If you use Arduino Due, you get a 12bit ADC, so your resolution becomes about 1 mV.