loading

From the minds at http://arduinotronics.blogspot.com/

Important Update!

Since so many people were having problems with the INA125P, we now have a new and improved version that uses the Hx711 24bit ADC amplifier module. http://arduinotronics.blogspot.com/2015/06/arduino-hx711-digital-scale.html


My goal was to create a programmable scale for weighing objects, parts counting, even directing product flow on a conveyor system.

I needed a load cell, a Arduino, and an amplifier.

Step 1: The Load Cell

On this load cell (from a Accuteck  W-8260-86W Postal Scale) the 4 wires coming from the load cell are:

Red: Excitation +
White: Signal +
Green: Signal -
Black: Excitation -

This matches the GSE / NCI / Sensotec wiring scheme.

http://www.controlweigh.com/loadcell_colors.htm
I disconnected the 4 wires from the control board in the scale, so they would be available for the next step.
Can u estimate from the results, what is the accurecy rate of the results? Is it possible to get grams?
<p>The HX-711 version is accurate, and outputs in grams.</p>
Thanks for your reply, can i count on it to return 50g differences?
<p>I've measured 0.05 gram differences</p>
<p>Amazing, thank you sir!</p>
<p>Can a load cell be programmed to alert when something weighs less than it did when it was first placed on the sensor?</p>
yes, you can program it to alert on any decision code you write.
<p>Thanks for the quick response. Would there be any instructions that come with the product on how to do this or is it something that only a tech savvy person knows?</p>
<p>The companies that make the parts have no way of knowing how you will use them, but they do provide data sheets. You have to know what you want to do with it, and how.</p>
<p>All the hacks on internet pertaining to load cell recommends use of an amplifier to get the signal readable by any microcontroller like Atmega (arduino). That's fair. But what I always wonder is how does the lcd work without an amplifier? How is that the scale is able to work without that amplifier??!! </p>
The LCD is digital, no amplifier is needed. it works on the same 5v signalling the arduino uses.
Hello. The amplifier is needed to change the signal (in this case voltage in anaologue form) to a readable level but proportional to what a load cell uses. The lcd communicates at the same voltage level already. A load cell system built for the arduini platform is already working witht he same voltage reqyiremwnts and will not need an aditional aplifier circuit. I hope that this is helpful. The sensors built for arduino are designed to be modular and have these presets already desig ed to work together.
<p>I have made same circuit but I am getting a problem in amplifying the voltage. I have tried this with a 3 wired load sensor in which I am keeping 2 resistors on the breadboard and 2 wires (black and white) coming out of load sensor are connected to make a Wheatstone bridge and I am reading the value of voltage between red wire of load sensor and its other end in Wheatstone bridge. Now when I am applying force on load sensor then it's value are changing ( very minute change but still change I have to amplify that). Now my problem is I am able to amplify the value of the voltage but the change is so minute that it's amplification doesn't show up in comparison to the actual voltage. How should I go about it?</p>
<p>I have weight sensor(load cell) 4 wire sensor+hx711 amp,+arduino uno r3, test code what i found at net working fine.</p><p>but how i adding code weight limit alarm led ?</p><p>mean if value = X then ledpin output hight else low. i try many code but no working ?</p><p>full code need be if button1 high ledpin1 high.(run pump) then value == X limit then ledpin2 high else low(alarm stop pump). but i try many time write code and all style not working ,how thats must made ?????? </p>
<p>Hi, sir! I have a project about BMI Machine and I use the load cell as my sensor in weight. I just want to ask if how to call the output of the amplifier so I can manipulate it in the program, and use it in my actuator, which is the servo motor. Thank you so much for the response.</p>
<p>hello sir, I use the weight sensor for my final project. so, I want to ask you some question about weight sensor coding. can I use, the arduino coding in the microcontroller coding? its same or not? or in microcontroller have a other coding to make a programming? that,s all. thank you.</p>
The arduino is a microcontroller, based on the Atmel 328P. If you have a different microcontroller, you will have to modify the code and library appropriately.
Well, I posted all the code that make this project work, so you are free to change the code, but it does require some C programming savvy. I am available for custom programming. Cost would depend on the scope of the changes, but might be as little as $25
<p>I got a Taylor scale (http://www.taylorusa.com/kitchen/food-scales/glass-digital-kitchen-scale.html) and can't seem to find the manufacturer, unless they are the manufacturer in which case they're not listed on the color charts you linked. The labels seem to be misaligned as well. Is there any other way to tell which are signal and excitations?</p>
assume red and black are power and ground, and white and green are signal, if scale reads funny, reverse white and green.
<p>Hello! Can you help me very urgent I need all the code for the operation of this scale var.l&uuml;tf hx711 I am using the Layout in this project? I'm sorry for bad english.</p>
code for the hx711 is at <a href="http://arduinotronics.blogspot.com/2015/06/arduino-hx711-digital-scale.html" rel="nofollow">http://arduinotronics.blogspot.com/2015/06/arduino-hx711-digital-scale.html</a>&nbsp;make sure you download and install the library.
<p>hey i want to know can i use AD620 amplifier instead of this one in the circuit??</p>
The code would be different.
<p>can you help me with the code i am using ad620 amplifier with pic18f452<br>and output after amplifier fluctuate's alot what should i do?<br>and i generate a formula from the practicle values of load (weights) and output voltage but it did not give write answer on proteus :(</p>
<p>There's no ad620, pic18f452 or proteus in this project. I regret that I cannot help you.</p>
im new to arduino.. wat basic launguage to prog arduino for all type of arduino project.? is there possible to create own library.? and wat language to be learn for library code....
arduino code and libraries are most commonly written in C/C++ it's easy to write a library, see <a href="http://arduinotronics.blogspot.com/2014/07/creating-super-simple-library.html" rel="nofollow">http://arduinotronics.blogspot.com/2014/07/creating-super-simple-library.html</a>
<p>Hi, We are creating a PoC with the load sensor attached to the shopping cart to weigh the weight of the items in the shopping cart. Can we use this kind of a scale fixed to the shopping cart. Do you see any issues?</p>
I don't see an issue. If the cart weight is included, subtract that out of your total before displaying.
<p>can this scale be applied to a travelling bag to show its weight?</p>
you can put anything you want on the scale, assuming you pick an appropriate load cell.
<p>Hi,</p><p>What do you suggest for a good measure with the load cell ? How the load cell should be set respect to the table ? Can you show more picture of the hardware configuration ?</p>
just look inside a postal or bathroom scale, see how they are set up. I reused the existing case.
<p>I have a 100 kg single point shear beam load cell</p><p>Could anyone tell me which amplifier i should use ??</p>
if it's a 4 wire, use the HX711
<p>It's a 5 wire</p><p>Could we use the same for that too??</p>
<p>I've not seen a 5 wire. Do you have a make and model?</p>
<p>In a load cell with five wires, the extra wire is going to be the shield wire. It&rsquo;s usually yellow and connects to the ground terminal with the other wire.</p>
<p>Thank you very much for your valuable feedback.</p>
<p>Hi! I am quite new to arduino and loadcells. I am using a 10lbs (4.5kg) loadcell with arduino and the INA125. I connected it as shown however using a 1k ohm resistance and the amplification is too low and I cannot detect a change with the program. How do I determine the gain I need and thus the resistance required?</p><p>Thanks!</p>
You can get gain information from the data sheet, (6 ohm is a better fit) but I no longer recommend the INA125. The HX711 is much easier to use.
<p>Thanks for the help! I'll try a much lower resistance (after looking at the datasheet I see that 6 ohm would be a much better choice) and I will look into the HX711 as well for future projects! </p>
<p>sorry, data sheet url, http://www.ti.com/lit/ds/symlink/ina125.pdf</p>
<p>In sketches, I usually see the pin inputs. I do not see the pins that the code looks at. Am I missing something?</p>
right in the loop:<br><br>int analogValue = analogRead(0);

About This Instructable

234,258views

110favorites

License:

Bio: Professionally, I'm an IT Engineer (Executive Level) and Electronics Tech. I'm a Amateur Radio Operator (KK4HFJ). I lived off grid, with Solar (PV ... More »
More by sspence:DIY I2C LCD Display with Inputs Raspberry Pi & the Neo 6M GPS Earthquake / Vibration Sensor 
Add instructable to: