#31 Load Cell project (part 1) Arduino Micro problems plus postman deliveries

[@jvernice]

Excellent tutorial on load cells. I have used them with a Raspberry Pi years ago to rebuild a packager with burned out electronics. The packager would count to X number of items from a conveyor using the load cell. When X was reached it would then trigger opening a chute flap (solenoid) into a box below. It was a simple, semi-automatic packager.

[@RalphBacon]

Very cool! My rather simple coffee reminder still works and is still being used! It taught me a lot about load cells, for sure. 😉

[@ruftime]

Thank you! Making a chassis dynomometer for RC cars, a replica of the full size DynoDynamics dyno I had in my race shop for 15 years. Now retired and teaching a stem class for kids based on everything RC😎

[@RalphBacon]

You sound very busy! Nice that you are disseminating your knowledge in that way, keep at it!

[@Roy_Tellason]

Re: static sensitive parts, they all are to some exent. I got an Uno and a nano from banggood not too long ago. The uno was in your typical sealed static bag, no issues there. The nano was in one of those bags that's foil on one side, with the other side transparent, and they had affixed one of those yellow warning stickers to it saying "CAUTION: Static Sensitive Devices". But once I opened it I found that they'd stuck the part into a chunk of styrofoam just barely big enough to fit between the pins, presumably to prevent the pins from getting all buggered up. Styrofoam! And not that pink anti-static stuff either. Re: Load cells. I did some work some years back to repair a box that was used to test big steel cable harnesses. Like the sort of thing you'd use to pick up a space shuttle or similar. The box (and the operator position) was behind a serious barrier, just in case one of those assemblies snapped while being tested...

[@RalphBacon]

Once a µC has been assembled (eg such as a Nano) I think it is probably pretty safe with minimal protection - but I would not use styrofoam! I plug my static sensitive components (eg MOSFETs) into carbon foam (very low resistance, albeit a little brittle). Interesting about the large cable tests - but probably all the same principle!

[@vonries]

I love how you define "practical."

[@RalphBacon]

It's all subjective, right Steven?! One person's practical is another's person's totally over-engineered solution. Ha ha! That said. I am STILL using this coffee cup coaster right here in my workshop (yes, I am amazed too).

[@vonries]

@@RalphBacon I'm just jealous, you have such a vivid imagination. I would have made the postage scale, even though I almost never mail anything.

[@subishkanna6326]

Hy Ralph s bacon......I live in India.....and your video is very useful for my project ..... Hope to see more useful videos from u...

[@RalphBacon]

Nice to hear from you Subish, and I'm glad the videos are useful for your project.

[@subishkanna6326]

Ralph S Bacon ...wanna contact u for doubts....your mail ID please

[@RalphBacon]

Just post your questions here, Subish, then others can jump in too.

[@DTCxPredator]

Hi Ralph, could you help me please. I'm trying to use the HX711 with a KeeYees Pro Micro but can't figure out what pins to use. I have found loads of stuff for other boards just not this one

[@RalphBacon]

The Pro Micro (whatever brand) is an 32U4 processor board (just like the Arduino Leonardo) so will be a bit different to the UNO. However, it will work pretty much the same as the Uno; you can use pretty much any of the GPIO pins and then change the sketch to those pins. That all said, you should really get this going with a standard Uno first so you know you have it working - _then_ transfer it to the Pro Micro, otherwise you are making it very difficult for yourself!

[@koktungthong9012]

Hi Ralph S Bacon thanks for sharing us you work. I also doing a load cell project but may I know why I keep on obtain fluctuate reading? Is it because I using a 200 kg load cell for measuring 40 kg compression?

[@RalphBacon]

You might get a *tiny* drift, Kok, of less than 1g for a 200Kg Load Cell but it should be pretty stable if you have connected the wires from the Load Cell to the HX711 correctly. I'd double check that these are all connected up correctly and that you have done the calibration correctly too.

[@wowcoolm860]

Ralph, There appears to be 2 main designs of HX711 amplifier - a red board and green board. Do you know if there are any performance differences between them?

[@RalphBacon]

The board colour is, I'm pretty sure, just branding. Sparkfun, for example, love to use red boards in their design just so that they are recognisable. The HX711 chip is the same for both boards though. Unless anyone else knows different...

[@pathakarchana01]

this is a basic question but what are those black connectors connected to each end of HX711? is the same connected at the end of load cell sensor as well?

[@RalphBacon]

Hello Archana! Those black connectors are called "header sockets" which as they name implies, accept a plug, called a header pin. Sometimes you get "header pins" onto which you must attach a socket. The Arduino that I use in that video has both header pins *and* sockets to give it the maximum flexibility whilst developing solutions. The cables that are pre-made and which come with either/or pins or sockets at either end are called "Dupont Cables" and come in strips of 40, very cheap if ordered from the Far East on eBay. The connector at the end of the Load Cell is indeed a set of Header Pins but I connected these up myself (the Load Cell just comes with bare wires). You may find my videos #3 and #4 useful as they describe some of the fundamental hardware you need when playing about with Arduinos (and for that matter, Pi boards too). Great to hear from you, I hope you find the other videos useful too!

[@2ndmileproductions]

At work, we fill bottles with product and we use a load cell to measure the weight of the product in the bottle. Our load cell has gone bad and that is why I am learning Arduino. The microcontroller in our machines is so old that no one knows how to make it work with a new load cell. Instead of buying a new $20K machine, I want to refurb our machine using less than $100 in Arduino parts.

[@RalphBacon]

You could built a pretty good scale using a Load Cell and an Arduino. MIght not be of the same precision as a $20K device but how accurate does the bottle filling need to be? If it's 0.1g then I reckon the Arduino will do it.

[@2ndmileproductions]

@@RalphBacon Our current machine is only accurate to 1g. I will let you know how it goes.

[@billfield8300]

Could you not use this device to measure the pressure being exerted during the use of a gripper or perhaps on the fingertips of a prosthetic?

[@RalphBacon]

Hi Bill! Interesting question. It will measure gripper pressure in the sense that it will correctly detect force (in one direction) but it is (relatively speaking) a physically large device so I'm not sure how you would incorporate that into a prosthetic to be honest. Moreover, it must be mounted so that the area you exert force on is 'floating' with the other end secured. Have you considered conductive foam that varies its resistance depending on how much pressure is exerted onto it? They're used in burglar alarm door-mats that get triggered when a human walks on them but they don't react to your domestic kitty walking over them. Just suggestin' ! Thanks for a great question, you never know, others may chip in here with suggestions too.

[@Drew_Summerfield]

Hey Bill, I posted a response to this question a couple comments up that may be of interest to you.

[@billfield8300]

Thanks Drew, I checked out the link and some of these seem reasonably feasible. Thanks for the intel.

[@Drew_Summerfield]

Absolutely, the gauges in the link are the type I work with at work, its a good representation of the different styles out there, I'm sure there are much more cost effective hobbyist gauges available.

[@sidibejefferson7926]

hi ralph , your video is really helpfull but i've got some questions about your code, where did you get your "arduino.h" , and "hx711.h" library since i'm not able to find these libraries i can't try it on my arduino, may i have some help

[@RalphBacon]

Hello Sidibe! I've added in a link to (what I think is) the library I used (I will double-check tonight), it's now in the video description. You won't need the "Arduino.h" library if you're using the Arduino IDE as it is automatically included for you behind the scenes. I only show it because I sometimes use a different IDE. But this library is part of the standard Arduino code so if you so include it no harm is done (and you don't need to download it). Good luck with trying this out and get a Load Cell capacity (the weight it will measure) appropriate to your project's needs (ie don't get a 10 Kg Load Cell and expect it to measure down to the last gram - for that you need a more sensitive Load Cell like the one I was using with a 500g max capacity).

[@sidibejefferson7926]

hello , Ralph thank you Ralph for the quick answer, i'm using the arduino IDE with a 5kg load cell, but i can not find the link in the video description would you mind showing it to me. best regards

[@RalphBacon]

Sure, I hid it underneath the sketch link: The library can be found here: github.com/bogde/HX711

[@sidibejefferson7926]

thank you very much ralph you are of great help thanks for sharing your knowledge , and i'm looking forward for new videos and projects that you will make. best regards

[@sidibejefferson7926]

hello ralph , well i have tried step by step to implement your code , can you please tell me where does calibration_factor=-2680 comes from because i do not have the right weight values, i do not know , why, furthermore i have checked the load cell wires everything seem to be ok

[@RalphBacon]

Hello Sidibe! I've updated the video description, look for the new DropBox link that mentions seed and calibration sketches (they are used in the demo and are really small). Run those and you will be able to get that magic calibration_factor (which could be ANY value, mine just happens to be a negative number but yours might be very different). Additionally, as Eric Gibbs has mentioned below "A £2 UK coin weighs 12.0gm and the new £1 coin weighs 8.75gm." If you are not in the UK perhaps you can find out what your coins weigh and use those instead of the tiny weights I used?

[@اختراعاتوابتكارات-ج3ع]

I want to connect the weight loading unit with the Arduino and when it reaches 1 kg, the LED works on one of the Arduino ports

[@RalphBacon]

Yes, you can do that once you get it working, it's quite accurate.

[@JenniferEliseAtchiso]

So... could a load cell be used in the 'hand' of a robot arm to control grip pressure? (I'm a beginner so be patient if you have already answered)

[@RalphBacon]

I'VE ALREADY ANSWERED THIS DAMMIT... oh, sorry, didn't read to the end of your post! Heh, heh, just kidding Jennifer, we were all beginners once (and I still am, as far as I am concerned). Benny is the guru, not me. Now... Now, the Load Cell is quite chunky as the video shows. It must be mounted so the "weighing end" is free floating. Absolutely nothing much touch it (no covering, for example). If all these requirements can be built into a robot hand then it would definitely measure grip (well, the pressure exerted upon it, in grams). If you can't physically fit the device into a finger/hand then how about conductive foam? That too changes resistance depending on pressure, although I don't know how durable it will be. Just suggestin'! Thanks for your question, Jennifer, and I wish you luck in your project!

[@Drew_Summerfield]

Jennifer, You can use this to measure pressure, the device under the glue in the load cell (The actual resistor network) is called a strain gauge, they come in various sizes from very very tiny to quite big. The sensitivity of the measurement they make is directly affected by the gauge chosen and the flexibility of the thing being bent. (Thats why there are holes in that bar, to make it more sensitive, without the holes it would still work, but would not read the very small weights) Here are some examples of strain gauges: www.digikey.com/products/en/sensors-transducers/strain-gauges/559?k=strain%20gages These can be wired to the same HX711 Ralph uses. Regards, Drew Read more

[@BLachance75]

Question for you if you don't mind. Is it possible to set it up so that the scale doesn't have to calibrate every time. What I'm trying to do is build something that will sit under a box that I can power up from an external battery that will display the weight of the box. The boxes are heavy and stationary and my ultimate goal is to have something that I can walk up to, plug in a little external box with a screen that will power the Arduino nano that is in the base the box sits on and display the weight. I can calibrate it and tare it out before putting the box on but after the box is set on it I don't want it to calibrate again, I just want the weight of the box and its contents.

[@RalphBacon]

That's exactly how my Coffee Cup Coaster works. Once it's been set (tared to zero) it will continue to work until I switch it off. Once I switch it back on (every few months) I just tare it (with my empty coffee cup on it) to zero and that's it. The calibration phase only occurs whilst you are building the code, as every sensor has a different 'magic number' as my demo shows, which could be anything from -32768 to + 32767. But once you have (accurately) established that using the calibration sketches, that number remains immutable for the life of the sensor. Pretty much. I notice this comment is under video #31, have you watched #32, it might make it clearer (I can't remember what I put in each one, sorry, my age etc).

[@BLachance75]

I just watched the second video and it did help. However once I set my box on top of the load cell I won't be able to lift it again to tare it. So when I do a monthly power up to check the weight I won't be able to tare it as the box will already be on the load cell. So I guess my question is do you think I can get it to work by calibrating it after I build a base, then tare it and put my box on and power it off. Then when I go out next month and power it on it will display the weight without having been tared again.

[@RalphBacon]

I see what you mean (I think). If we think of a kitchen scale, you are leaving the mixing bowl on the scale, setting it to zero, using it to measure the ingredients, then switching it off. The next day you just want to continue measuring ingredients without lifting the bowl off first. I think this is what you mean. So... Yes, you can do this. In my second video I use a small tilt switch to act as the zero/tare switch for when I switch on (or at any time) place my current coffee cup on the coaster and tilt it so it starts the zeroing/taring process. So if that were a proper (external) switch you would switch the device on (with the box on the Load Cell), press this switch and at that point it would zero-ise correctly taking into account the box already on it. You are using a 200Kg Load Cell; remember this is the total weight it can take, including the box already on it, so make sure you have accounted for this. Sounds like a nice project. You connecting it up to an LCD or something similar for displaying the actual weight?

[@BLachance75]

You have it right with the kitchen scale analogy. What I'd like to build is build a base with a load cell that a beehive will sit on. I will then calibrate the base then tare it with an empty hive. Then I will build a small box with a power supply, the Arduino and a LCD display and plug the load cell into it so I can monitor the weight of the hive in the winter. I would build a base with a load cell for each hive then go from hive to hive and plug in the load cell to get the weight to display on the lcd display. I don't need super accuracy, within a few pounds would be sufficient.I'll have to play around with it this winter and try to figure out the coding then implement it next spring. I don't have any issues dealing with the building of the bases or electronics it is the code that I will have to figure out. If I figure it out I may try to expand on my idea and add thermistors inside the hive so that I can check the temperature as well.They have commercial products that do what I want but they are very expensive. I'd like to try to figure out a more economical option for other backyard beekeepers like myself.

[@RalphBacon]

That all sounds feasible, just remember that each Load Cell will have a different calibration value, so you would either have to enter the calibration value as part of your sketch for each hive (as you move around weighing them) or store the values (in EEPROM, for example) and select hive 1,2,3... etc so that you were correctly measuring the weight for each Load Cell. But it sounds very do-able, so good luck with this.

[@TheAppleFanBoyAppleArchivesUS]

Hello, I work with this HX711 amplifier, for a communicating mailbox project, when there is a letter / parcel, it sends a notification to a phone: D, I would like to know how many bytes are transferred per second , moreover I do not know how are connected the pins CLOCK AND DAT.Thanks !

[@RalphBacon]

Hello AppleFanBoy! The Sparkfun datasheet for this device states that you can select either 10SPS or 80SPS. The CLOCK is driven by the microcontroller and the DATA OUT is read by the µController. Your best best is to read in some detail this document(cdn.sparkfun.com/datasheets/Sensors/ForceFlex/hx711_english.pdf) or buy a module like I use in the demo (so much simpler, IMHO). Have fun with this!

[@TheAppleFanBoyAppleArchivesUS]

Thanks :D

[@rksystemrajesh]

sir,very good work,and expline...u r a best teacher....

[@RalphBacon]

Thanks and welcome!

[@chipfriday8166]

What does bricks itself mean?

[@RalphBacon]

The term "bricking" refers to what happens when your turn a useful piece of electronics into something as useful as a brick. In other words, not very useful at all. So if you apply too much power to an Arduino, for example, you will "brick it". It can also apply to computers and smartphones when flashing new firmware; if you are unsuccessful you will have "bricked" your phone or computer because they no longer function and now resemble a brick in terms of usefulness! Hope this helps. Good question!

[@jamesearlcruz1206]

Hi! Im a student and has a project regarding these but planning to use it for weighing person, can I use a 50kg load cell to measure higher loads? Maybe callibration ?

[@RalphBacon]

Yes, you can use a higher capacity Load Cell, James, but for measuring people (or other heavy objects, like elephants) you would normally use a slightly different setup. In that case, you would use 2 or 4 50kg Load Cells configured in a half bridge fashion with three wires per sensor; when you connect 2 or 4 of these sensors up they make up a full bridge. The sensors should be closely matched for impedance (the seller will state if they do that). The HX711 supports 2 Load Cells but I'm not sure about 4. You'll need to read up a bit about this. What can I say? This is more complex (=typical British understatement) so I'd get the simple demo version working correctly 100% before moving onto something like this if you value your sanity (and spare time).

[@menagahsaravanabavan6959]

hi! I'm a student also and i'm using 2 load cells(50kg)+hx711.When i upload the coding in arduino(arduino uno) it shows 0kg at serial monitor no mater how much i pressed it...i think there's a problem at calibration factor...can i know how much calibration factor do I have to put in order to get a accurate reading.....

[@SharaafAhamed]

Great video. Sir I am doing a project based on load cell. I flowed your video.. But the problem is my load cell is not giving the correct measurement. for ex. 140g is shown as 79.5g. if the weight goes up it shows less weight than the original weight.. What is the actual problem here. what should I need to do to solve this

[@RalphBacon]

I'm going to paste in the same reply I gave another subscriber as this seems a bit of a sticking point! --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- It’s important that one end of the load cell is securely screwed down onto a piece of wood (or something) so that it cannot move about, just like in my first video #31. This enables the other end (that is now free-floating) to move a millimetre or so when weight is put upon that end. Important: fix the end of the load cell to a support which does NOT have the weight sticker on it. Secondly, I notice from your pictures that you have a 5kg load cell (I used a 100g load cell, quite a difference in sensitivity). It MIGHT be that your load cell cannot accurately measure small weights like 50g and perhaps you should use an exact 0.25kg weight to start with and see if you can get a proper, repeatable reading. You may have to hang the weight from the load cell over the edge of a table otherwise it will not be easy to do. During the calibration phase it does not matter if the final calibration factor is negative or positive but it should be stable. So, check the following: 1. Have you have wired up the load cell correctly to the HX711? The four colour-coded wires from the load cell are very specific (two +/- pairs, not interchangeable), see the data sheet 2. Have you mounted it correctly on a board in the same way I did so that the correct end is secured and the other end can move without hindrance? 3. Have you got a weight large enough so it registers in the calibration stage the same weight, repeatedly? That’s all I can suggest at the moment, but if you follow the same steps I took it most certainly will work, so good luck. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- That's it, I hope it helps!

[@SharaafAhamed]

U have used this green colored HX711 module img.dxcdn.com/productimages/sku_308904_1.jpg We are using this red colored one. cdn.shopify.com/s/files/1/0672/9409/products/weight_ADC_large_faba79ae-ae57-4d30-8550-e4f0d7885dba_1024x1024.jpg?v=1438621867 what is the difference between these two modules???

[@RalphBacon]

As long as the E+/E- is not used then both boards are (probably) the same. They both have the HX711 chip on board and there's only so many way you can connect that chip so I suspect they are the same. My board might allow other weighing sensors to connect to those E+/E- pins but I haven't really investigated that option as I'm trying to keep it simple here. My board was purchased from Banggood here: www.banggood.com/5Pcs-24-Bit-AD-HX711-Weighing-Pressure-Sensor-Module-For-Arduino-p-953336.html and they are still selling these $5.28 as I write this; not exactly cheap but mine has performed flawlessly since I built it into that coffee cup coaster. Edit: that was $5.28 for FIVE pieces so in that case they are VERY cheap individually!

[@eliasbrow]

Hello. In my project my cell load with hax711, read weight negatives, help me please. tks.

[@RalphBacon]

It means you did not follow all the steps properly, I'm afraid. Or you have wired up the load cell wrongly. It's always one or the other. Recheck your work and do _exactly_ what the demo shows (and the video following this one), then it will just work.

[@CarAndMechanical]

Hi Ralph, great video very in depth. Do you know or have any thoughts about running these in series the achieve a higher max weighing potential (on ebay I'm seeing max 50kg before prices skyrocket)

[@RalphBacon]

What normally happens is that you 'bridge' more than one sensor - your bathroom scales has two or four of the 50kg sensors, for example. The HX711 can have two connected in that mode (but you will have to research the wiring, I'm afraid) or there may be 'kits' that have four sensors and a different chip to detect the weight. I hope this helps.

[@CarAndMechanical]

Hi Ralph thanks for the quick response. I'll get a few ordered and have a play with regular scales before ramping up.

[@RalphBacon]

Absolutely, get it working 100% using a single unit then move on to the advanced stages. Good luck with this.

[@CarAndMechanical]

Spoke to my friend about this and he's said to me this project is fine but use the 50/100kg set up but with levers so that'll make it inetersting to achieve the higher weights.

[@RalphBacon]

With levers? You need to get your friend to explain what he means by that. What is their purpose?

[@LucioVazquez]

Thanks for posting this video! I am working on a project and found this really useful.

[@RalphBacon]

You're most welcome and thanks for posting the fact you found it useful. I use my Coffee Cup Coaster daily at work but have yet to make another for home use. If you'd like to share what you are using a Load Cell for that would be useful not just to me but others reading this message.

[@gauravpatil4035]

i wanted to make a PROTOTYPE system in moving train of kids toys. now if the weight will overcome 50 gram in first coach the door of next coach will open automatically.(resulting into saving electricity & reducing wear & tear of wheels pf train since until the coach is closed people wont be there inside the coach -considering the original or real situation of trains now a days) I have tested the engine of this toy can only carry 200 grams upto maximum limit . Now it is necessary to put the microcontroller & motor & one other circuit on that train which might weigh 80 grams for door opening is there any load cell that weighs 50-80 grams & can detect 20-50 grams or should i use any other component & one more thing where to find the PROGRAM for such projcts or my project

[@RalphBacon]

I'm not sure I understand how you are going to weigh the train if the module you are using is ON that train. Surely the easier way would be to have the equivalent of a train weigh-station so that as the train pulls up at the station, the train(or some of it) is being weighed (by a Load Cell, for example, on which the tracks are laid in the usual way). Effectively it becomes a floating length of track but as the actual vertical deviation is tiny it would probably just be part of the standard track. I would suggest that you experiment with the same Load Cell as in my videos; once you have that working I think you will have a better idea of what would work and what would not. Just suggestin'!

[@miraclelau4640]

I enjoy your video a lot. This project is cool and I want to try one too. Could you tell me which wire of the load cell connect to which pin of the HX711? Also which pin from the HX711 to which pin in the Arduino Thank you so much

[@RalphBacon]

Well now, Miracle (love that name), the HX711 boards are normally colour coded with names like "RED, BLK, GRN" etc marked on the board and which correspond directly to the Load Cell wires. If your HX711 board does not have this, then it probably has "A+, A-" and the like. In this case, Red is E+, Black is E-, Green is A+, White/Grey is A-. NOTE: The A+ and A- wires may need to be switched but try it this way first). The seller has this documentation: Wiring Red: Power + Black: Power - Green: Signal +, White: signal - On the other side (the wiring to the Arduino) you have the standard 5v power and GND connections and the centre two pins are the DATA and CLK lines - see the sketch to see which pins are expecting this information. Don't connect anything to the "B+" or "B-" terminals (if you have them) as they are for a dual/bridged load cell. Let me know if this does not work for you.

[@miraclelau4640]

Thank you so much for your response. I enjoy your weight scale video

[@gauravpatil4035]

hello i have not even a bit of idea about automation.but i want to make project on " automatic door open & close system based on weight sensing (that will detect the weight in grams) im pretty much sure i can do it with aurdino m/c but what should i use as weight sensing (that should be very light in weight as i have to put it on toy) load cell, pressure sensor or strain gauge or any other component plz help me..& plz rply

[@RalphBacon]

Hello Gaurav! Yes a Load Cell is ideal for sensing weight as my videos #31 and #32 demonstrate. And they are very light and sensitive (especially if you get a 500g Load Cell like mine, it can detect down to 0.5g). So it should be OK for your toy set up. If you give me more details on what you are trying to do I might be able to suggest more. Thanks for posting, good to hear from you.

[@Mustafakhan-lq1pz]

hello sir., i am working on my project... i am using arduino mega board 2560.. but i have to use 4 load cells each of capacity 40 kg.. what kind of amplifier should i use to connect them all.. and what changes are needed in the code/sketch you have given above... and what about the connection with mega board means how to connect with mega board... i would be thankful if u replied to this comment... thanks

[@RalphBacon]

When you say you are using four load cells, Mustafa, are you using them _independently_ or as a single weighing unit that can weigh (up to) 160Kg? I've not done a video on using more than one Load Cell, although most HX711 boards will allow two to be connected up as a bridge. You will have to Google the answer for using four connected cells, I'm afraid. Using a Mega 2560 is no different, really, to using an Uno. The code is the same, although some of the pins might change, but as you have this board you presumably know the pin numbers and what they are used for? You might want to consider building the sample project "as-is" so you get some experience of using a simple, single Load Cell first and then progress to your four-unit project?

[@Mustafakhan-lq1pz]

Thanks for replying sir......i'm using them as a unit . the four load cells are combine through a "Load cell combinator" by the same wheatstone bridge principle and then the four wires are connected to a Load cell amplifier and then the next to arduino board.. but this thing is not giving me a reading.. i dont know what to do know.. I have tried a single cell but the cell i'm using, consists of three wires, again no luck.

[@esraaltun1551]

What is hx711 slave address for I2C communication?

[@RalphBacon]

Hello, esra altun, I'm afraid the HX711 is not an I2C device and therefore does not have an I2C address. If you use the HX711 library as shown in my demo you just supply the two digital pins you have connected the DT and SCK to and then you're good to go. I hope this clarifies things!

[@miller866]

Hi Ralph - Nice video! CAn you tell me where you got the load cell?

[@RalphBacon]

+Scott Miller Hi Scott, welcome to my channel. Excellent question and I can't believe I didn't show this in the video, very remiss of me. Anyway I bought it from eBay from Far Eastern seller myfree8. Here's a link to the item in the UK (but he will doubtless sell on all variants of eBay): www.ebay.co.uk/itm/Aluminum-Electronic-Balance-Four-Wire-Weighing-Load-Cell-Sensor-YCZ-191-500g-/191598861371 Interestingly, well, sort of, the price has gone DOWN since I bought this in early April 2016. Note that this is the 500g version as I wanted to just measure a coffee cup and wanted the resolution to be high (and that coffer cup coaster is in DAILY use, gets lots of enquiries and just works so wonderfully well I should have patented it). He/She/They sell other variants from 500g to 5kg or more, get the version to suit. Thanks for the question, I shall put that link into the video description too :)

[@sahilpatel9233]

Hello I'm a High School Student and I was wondering how did you get each reading to print on the serial monitor only once? When I try it out it prints 100s in the matter of seconds. Please help

[@RalphBacon]

You're probably reading the LoadCell too often, Sahil - several dozen times a second! Try putting in a delay of about 100ms between reads. Alternatively, compare the value to the previously read value and if they are the same do not display again (until it changes).

[@Rajatkamble39]

can i use this to find impact load?

[@RalphBacon]

Not really, the load has to be steady in order for the measurement to be made, it's not meant for abrupt changes.

[@Rajatkamble39]

@@RalphBacon could you please recommend me any sensor or a device which I can use to find impact load of around 20N

[@ericgibbs301]

hi Ralph, Ref the Coffee cup load cell. A £2 UK coin weighs 12.0gm and the new £1 coin weighs 8.75gm. I use a stack of £2 UK coins for calibrating in 12.0gm steps Eric

[@RalphBacon]

Brilliant idea, Eric. Did you already build this (in some form or other, not necessarily a Coffee Cup Coaster)? Now I think of it, your idea is great bar one HUGE flaw. You say you use a stack of £2 coins to calibrate with. There's the problem. A whole STACK of £2 coins? I'm lucky to find one and a dead moth in my wallet, plus an old W H Smith receipt. :) Heh, heh, just kidding, a great suggestion and thanks for sharing as I know others have wondered how to calibrate their Load Cell without buying a set of weights like mine. Thanks for posting.

[@bissoruben]

hi Ralph, Thanks a lot for the video: but I have a worry with reading. My analogread value from the load cell sensor 40 kg is just constant even when i press the sensor there is not variation. please, I need a help!!

[@RalphBacon]

This indicates a problem with the wiring, Tjade, and I suggest you revisit that first. Look at the spec/data sheet for your particular Load Cell so that you get the correct colours connected to the A+ etc. If the wiring is 100% then you need to implement the very first sketch to calibrate your Load Cell and get the seed value. Try all this first!

[@bissoruben]

okay, thanks you!! Let me try it!!

[@bissoruben]

I try your recommendation, but the value is still steady. I supply the load cell with 9v battery, no response!! I bought 3 HX711 and two load cell sensor 40 Kg. There is no variation!! I am discouraged!! If you any idea, it is welcome!! thank you Sir Ralph!!

[@RalphBacon]

My final piece of advice would be to buy the *exact* same Load Cell (500g) that I bought (details in the video) and construct the project *exactly* as I did it in the videos, starting from step 1. We *know* that works so if you follow that, get it working then you will not be discouraged and will have renewed enthusiasm to then work out what the problem is with your *advanced* project. That is my recommendation. It will not cost much to do this (you already have the HX711 module). And use a proper USB connection and/or 9v plug in supply, not a battery. You will need to see the results from the Arduino via the Serial Monitor anyway, so use the USB port. What do you think? Thoughts?

[@bissoruben]

Thank you Sir for encouragement!! I will follow your instructions. Next time I will surely give you a positive feedback!!

[@johannessteenkamp7944]

How do I sensitize it to measure how much left in a Tod glass?

[@RalphBacon]

I'm assuming here, Johannes, you mean a tot (as in shot) glass, not Tod(d) Glass, the famous American stand-up comedian? If you use a 100g Load Cell as I did it will EASILY measure down to the last dribble in the glass, as per my coffee cup coaster does, every day. What Load Cell are you using? And what sketch? If you use both a 100g Load Cell and my Coffee Cup coaster sketch then it will be no problemo. Let me know your set up.

[@johannessteenkamp7944]

Ebay no name cheap loadcell. We can call your Todd a shot for my purpose (25ml approx) Thanks will post sketch soon.

[@RalphBacon]

The critical factor here, Johannes, is the max load of the Load Cell. A 100g cell (like mine) is very sensitive right down to the last 1/10 of a gram. If, by chance, you're using a 1 Kg Load Cell then I think you will have problems getting it sensitive enough. As you say, though, get it up and running whatever the capacity because you can always swap out one Load Cell for another and just re-run the calibration routine.

[@corbinmacphee6505]

cant find sketch on your github would really like to see it so i can try your setup please lemme know asap where to find it / send it to me

[@RalphBacon]

The main repo is here, Corbin, let me know if there is anything missing that you need: github.com/RalphBacon/Load-Cell-Part-2

[@87Edvin]

The dropBox sketch link is down? Can you plz reupload. Thanks

[@RalphBacon]

Thanks for letting me know, Edvin. I've moved all the files for this video to my Github: github.com/RalphBacon/Load-Cell-Part-1 as Dropbox no longer worked. Let me know if you have any further problems and good luck with this project.

[@87Edvin]

I've been using different sketch's, got my load cell calibrated, but struggling to stabilize it when there is no load. The lcd still prints negative even though I use if else statements to tell it to display 0.0 grams if the value goes negative. I'll try out your code, thanks!

[@RalphBacon]

Good luck with your project, Edvin and thanks for posting.

[@beatlessteve1010]

It seems as though you could accomplish the same effect with simply using a micro limit switch to activate the "cup full " alarm

[@RalphBacon]

Well, it's not the 'cup full' I need to know about, Steve, it's the half cup, quarter cup, dribble-in-the-bottom-of-cup that I want to be reminded of. Also, different cups are different weights so a µswitch would not know I've put a different cup on the coaster and would tell me there is coffee left when there isn't (or vice versa). The only way to 'intelligently' work all this out is by knowing the weight of an object - which the Load Cell excels at! And, to be honest, this was just a rather tongue-in-cheek project to demonstrate the facilities of the Load Cell - but one which turned into a rather nice coaster with lights (see video #32) and which visitors to my desk are intrigue by (at which point I mention dilithium crystal realignments just to blind them with Star Trek science, works like a dream!)

[@paulsharpe3794]

Hi how about fitting it to the bottom of your post box to let you know when you get mail

[@RalphBacon]

A brilliant idea Paul! This would work well in the United States where mail gets delivered to funny looking mail boxes at the end of the front garden (although the postman raises a flag too) - but you'd need power out there, either running up the mail box post or solar power (let's face it, post is unlikely to be delivered at night). In the UK, it's a little different, as all mail is delivered through the letter box of each house (no outside mail boxes at all) but it could sense the mail falling to the floor in the area of the letter box, as long as the mail didn't waft up the hall too far! I'm not sure how mail is delivered in the United States in cities with apartment blocks; I'm assuming the mail goes into mail boxes for each apartment in a communal area, which could make it tricky too. My parents' mail is delivered to an external mailbox outside their apartment building but there is no way the landlord would let them start running power to those (shared) mailboxes - nor can they drill holes to provide power by using solar power. So for many people it would work, and for many it would not. But it's a great piece of lateral thinking and perhaps someone reading this will think "Yes! I'll do this" so thanks a bunch for posting (obviously I don't know where you are located in the world, so I covered a few bases here for the benefit of anyone reading this not familiar with the way post is delivered in some parts of the world). Good to hear from you Paul.

[@paulsharpe3794]

Ralph S Bacon hi I live in the UK and have a postbox fitted to the inside of the front door to stop the dog playing with the post

[@RalphBacon]

In which case your idea should work 100% - fantastic!

[@michaelhenderson5098]

In my neighborhood (Houston,Texas), our mail is delivered to a gang (cluster) box which is on the next block about 150 feet from my front door. :( Now a box for Amazon deliveries by the front door would be a great candidate for this project!

[@davidrichardson376]

How about weighing a flowering planter pot when it's dry and again when it's watered (and has drained the excess). Next time you could give the plant exactly the amount of water it needs ! (lol)

[@RalphBacon]

Not as silly as you might think! Sounds ideal. Let me know how it goes. Blooming marvellous.

[@markzeidan9713]

Have you tried creating this project with the esp8266?

[@RalphBacon]

+Mark Zeidan I can't say I've tried that, Mark, but as you only need the one analog pin (all you get on an ESP8266) it should be OK... I think (without actually doing it that's all I can say). Then you can wirelessly send out a message or allow your ESP8266 to be interrogated. I (and others reading this) will probably be interested in what you might use this combination for as we're always eager for new ideas. Thanks for posting and enjoy the other videos too!

[@MuhammadRizkyEkaArlin]

Very amazing video. I saw that your 500g load cell has the precision of 0.1g. So is correct if I assume the precision for 1kg load cell is 0.2g?

[@RalphBacon]

Hi Muhammad! I'm not sure it works like that as the manufacturer could put whatever precision on the Load Cell they please. The only definitive way of knowing the precision is to read the Data Sheet (if you can get it for the Load Cell you're interested in). Failing that, the only other way is to actually try it! But it's a fun, inexpensive project, that's for sure! And I'm using my Coffee Cup Coaster *every day* at work, and it tells me whether I still have coffee in my cup or not. Thanks for posting, now go and experiment with Load Cells!

[@MuhammadRizkyEkaArlin]

thank you for the suggestion. I'll definitely do it. And... I'm going to subscribe your channels :D

[@mevalia]

Up to 50kg... I work in a compagny wich sometimes makes load cells over few MN (with another design).

[@RalphBacon]

Well, I suppose the weigh-stations that measure laden trucks with many tons must use a similar method so I'm not surprised that there are some "industrial" versions of this! Good to know and thanks for posting.

[@martinkeatings7126]

Just a wee suggestion. I always used to use a whiteboard for designing and planning stuff. Then I went a bit more high tech and started using a sheet of perpex (clear) and a liquid chalk pen. Sounds daft but bare with me. What I did with the perspex was to stick EL strip / LED strip (like this image.ec21.com/image/gtwelight/oimg_GC04337740/EL_Strip%252FLED_Strip.jpg) around the outer edge of the perspex. Then I put over the top of that, edging (like this www.woolies-trim.co.uk/p-1578-chrome-edge.aspx) over the edge and around the perimeter of the sheet of perspex. On the inside of the edging (before putting it on I put some chrome paint so the inside of it was reflective. The edging, apart from being nice to look at and hides the LED, also stops the led light from escaping outwards. The chrome paint on the inside bounces the LED light back towards the edge of the perspex and because the perspex is clear the light transmits through it and my board lights up like a beacon. Of course with the liquid chalk it goes florescent - really cool. If you did this with your coaster, you wouldnt have your led showing and the entire coaster would light up. Even cooler, if you put say red along one edge, blue across another and amber on another and fit your coaster with a temperature sensor. You could have the red come on when its hot, orange when its meeeeh, blue when its cold. So you if you look down and its blue you can go....bugger! coffee is cold! Then it stops you having that take a swig - BLLAAAH moment with cold coffee.

[@RalphBacon]

Amazing lateral thinking here and it does sound cool (or hot - no pun intended). I've yet to build my coaster for home use (this time using smoked perspex) so I'll consider this and other suggestions I've received on how to make it look (even) better! The main issue I have is (lack of) time, it just takes several hours to build stuff - several hours I never seem to have. Thanks for your post, I found it very interesting, as will others too - appreciated.

[@martinkeatings7126]

If you are using smoked perspex this might not work. Ive only ever seen it done with clear perspex because of the refraction and polarisation index of the perspex

[@davidrichardson376]

Be careful not to exceed the maximum rated load. Once the linear "spring" range is exceeded the device becomes useless.

[@RalphBacon]

I expect the bar would become deformed and never work again.

[@kaylrabanzo8425]

Hello :) how to know how much is the calibration factor of 200kg? Please notice me :

[@RalphBacon]

It's not a known amount, Kayl, you must follow the instructions in the video for your particular Load Cell. They are all different. Unless and until you have the Load Cell you will not be able to determine the calibration factor. I hope this helps you.

[@kaylrabanzo8425]

Ralph S Bacon thank you sir. Sorry sir me and my groupmates are also begginner can i email you sir for some questions?

[@RalphBacon]

Put your questions right here, Kayl, and I'll see what I can do - but remember that I won't do your homework or school project for you! I need evidence that you've given some thought to whatever problem you are facing and that you have tried things already. OK?

[@kaylrabanzo8425]

yes sir :)

[@jaimecalderon1189]

I just view your video regarding Arduino and Loading Cell. You might want to monitor weight loss over time. For example, the loss of weight of a beverage (carbonated pop) as CO2 is escaping the glass. Thanks...!!!

[@RalphBacon]

You could indeed monitor that Jaime, but the weight of CO2 is tiny compared to the liquid, I wonder if it would even register? According to my school boy chemistry one litre of CO2 gas would weigh just under 2.0 grams. That's *one litre* of gas. How much in a can of cola though? Interesting post, good to hear from you!

[@AndreLuiz-dz1qk]

Hello, first off all I want to congratulate you on the videos, them help me a lot about load cell and arduino. But I'm a freshman with arduino. I'm from Brazil and I'm a Master's Degree student. I will develop a load cell with arduino's suport, but I don't know what arduino's board to buy. So, I'm in doubt about 3 models: Arduino Uno R3; Arduino Uno R3 Mega328p Ch340g (it seems to me that it is not original Arduino but supplies what I need) or Arduino Nano V3.0 Microcontroller Atmega328p. The last one is the cheapest and as it is a university work is more attractive , but I am afraid of her not to fulfill my purpose. Sorry for my bad english. Thanks for all your help.

[@RalphBacon]

Ola, Andre! Você fala Inglês muito bem. Unfortunately you speak English better than I speak Portuguese these days so we'll continue in English! If you are starting off with the Arduino you need an Uno R3 (clone). They might be described as Uno V3 or Uno v3 CH340G. The "mega328p" is the name of the actual microcontroller chip on the board, and they all have this, even the original ones! The difference in design between a real Uno R3 and a clone is that a clone has a different chip for the USB to serial conversion (it's a CH340G), because it is cheaper. From the Far East you can get an Uno R3 clone for US$4 or less. However, for better flexibility you can get a Nano Development Board like this one: www.aliexpress.com/item/Smart-Electronics-for-arduino-Multi-Function-UNOR3-UNO-R3-Nano-3-0-Shield-Expansion-Development-Board/32684416839.html into which you plug in a Nano R3 Atmel 328p (not an Atmel 168, that's a different chip with less capacity), like this: www.aliexpress.com/item/1PCS-Promotion-Funduino-Nano-3-0-Atmega328-Controller-Compatible-Board-for-Arduino-Module-PCB-Development-Board/32832925868.html I also recommend you watch my videos #3 and #4 which give you some basic hardware recommendations too. Tudo bem?

[@AndreLuiz-dz1qk]

Hello!! Your portuguese is very well (the google translate always support me when I finish writing). Thanks for your advices. The prices from the Far East are so attractive, but here in Brazil we have a problem with the deadlines, the products take from 2 to 3 months to arrive, I don`t have much time to start my project. If I can a lit more abusive, If I buy only the Nano and the Hx711 Can I have good results? Like at the end of this video. By the way, it's the model this I wish to buy (We have a site like ebay, it`s called mercadolivre): produto.mercadolivre.com.br/MLB-842983643-arduino-nano-v30-microcontrolador-atmega328p-ebook-_JM or this: produto.mercadolivre.com.br/MLB-767538993-arduino-uno-r3-mega328p-ch340g-cabo-usb-e-tutorial-_JM I will watch the videos right now.

[@RalphBacon]

Ola, otra vez! (Or am I now speaking Spanish?). Anyway, either of those two modules will be OK. If you get the Nano with the header pins NOT already soldered in place then you can solder them the other way up (so they are pointing upwards not downwards). It's easier to attach Dupont cables to them in that way. If the header pins point downwards then it is easier to plug into a breadboard but I don't think it is the best format for that module. The UNO is fine as it is. Either one of these modules with the HX711 will work. If you are only doing this for a project then get the 500g Load Cell in my video so that you replicate it exactly, including all the wiring. Then you can be assured of success! Boa sorte com seu projeto.

[@AndreLuiz-dz1qk]

Hello, almost portuguese. You missed one letter of word "oUtra" but is fine. I bought the UNO and the HX711. However I still have to buy the strain gauges and machining the load cell. When I start the work I come back here. Thanks a lot.

[@stoodyburner1]

Load cells can be made to handle over 1 million pounds. Research this. Used to read rocket thrust. Amazing technology.

[@RalphBacon]

Amazing technology it is, I agree Kenny. And the fact that they can, on the one hand measure 1 million pounds of rocket thrust and yet on the other hand measure 1/4 of a teaspoon of (cold) coffee in my coffee cup is proof! Great to hear from you, Kenny.

[@j1952d]

Project idea: auto cat food dispenser. Don't feed cat if cat too heavy!

[@RalphBacon]

Ha ha! That would have meant that Benny would never have got any food.

[@martinkeatings7126]

You mentioned you can get them up to 50KG - I just bought one for a project im doing and it goes up to 500KG :-)

[@RalphBacon]

OMG what are you weighing, a truck? An entire rugby team? A hippopotamus (perhaps you work in a zoo?) :) But seriously, thanks for letting me (and everyone else reading this) know that larger sizes are available as I'm sure there is a market for weighing bigger items. Did you want to share what you are using yours for, or is is confidential?

[@martinkeatings7126]

Actually I have been trying to measure volume of a liquid in a 100L drum. Flow meters are just too imprecise so I decided to use load cells instead. The density of any substance is the mass (in kg) of the substance posessed by unit volume( 1 cubic meter) of the substance. The Density of Water is approximately 1000Kg/m3. Hence converted in litre, density of water becomes 1 Kg/Litre. hence mass of 1 L of water is 1 kg. For me I am using several different types of liquid so all I did was weighed 1L of the particular liquid on scales, that gives me the weight of that particular liquid, from there it is just maths. So in otherwords, to measure out 100L of a particular liquid, I work out its density. For the first liquid I use I calculated that it weighed 940g per litre. So I put the empty drum on the measuring platform with the load cells in it and zero it. I then get it to switch on the pump and when it gets to exactly 94KG in weight, I know I have exactly 100L and switch the pump off For water I would zero the empty drum on the load cell, start the pump, then when I hit 100KG, I know I have 100L.

[@martinkeatings7126]

I can tell you what im doing for that particular part of what I am doing - just not the overall plan for world domination. LOL

[@drbizzarow]

Excellent !!! regards from Pakistan :)

[@RalphBacon]

You are most welcome drbizzarow, I'm glad you like the video. Nice to hear from you.

[@hasnulaidit]

hi, i am a student, i using 10kg load cell, when i put load on load cell, the reading is always 0kg? why is it? can you help me please

[@hasnulaidit]

btw i using arduino uno

[@RalphBacon]

Did you follow *all* the steps in both videos, including the calibration? You would already have discovered that you would be getting readings if you had, so I suspect your wiring. Double check all wiring and follow all steps in the demos and you will have success.

[@hasnulaidit]

Can i know how to make the reading really stable?

[@hasnulaidit]

How to make the reading not fluctuating , how u remove the noises? By software and hardware?

[@MB-lh5kw]

I have my load cell under my gas bottle on my bbq so I k ow how much gas I have left

[@RalphBacon]

A good Real World example of a Load Cell application, thanks for sharing Mark.

[@michaelhenderson5098]

Great project idea. Especially since I just bought a 36 inch Blackstone griddle! :)

[@ayugustiarapasha2816]

thanks sir^^

[@RalphBacon]

Thanks for your post, Ayu Gustiara Pasha.

[@ayugustiarapasha2816]

Ralph S Bacon sir, i want to ask. in ur coding "#define RST 4" . from pin 4 i must to connect where? thankyou

[@RalphBacon]

This is the "zeroise" or "tare" function of the weigh function - it goes to an external switch (I use a small tilt switch but a standard push-to-make switch would work too). When pressed it tells the sketch to "zeroise" the weight on the coffee cup Load Cell (eg with an empty cup on it, so the weight of an empty cup is considered to be zero weight - only the contents then are measured). Understood?

[@ayugustiarapasha2816]

Ralph S Bacon thankyouu so muchh sir, now i understand^^ . ur video are helpful for my final project.

[@RalphBacon]

Thanks for letting me know, Ayu, and good luck with your project. And do tell everyone about this channel!

[@SkipFlem]

Gee...don't I miss windows(not)!

[@RalphBacon]

Oh don't say that, I'm just about to upgrade to Windows 11. 😲

[@MPElectronique]

Its a funny project :)

[@RalphBacon]

Funny ha ha, or funny peculiar, Marc? It works very well though in measuring things, and I _still_ have my coffee cup coaster on my workbench next to me!

[@Jimbojenkins]

what is "capativie"? is it more of "arduino" speak?

[@RalphBacon]

Probably more likely more of my mumble-speak, Jimbo! Where in the video does this strange word appear?

[@buckstarchaser2376]

Enough of this unwashed, digital coffee scale horde thinking. Join the laser, retro-reflectometry coffee level master race.

[@RalphBacon]

That is some sentence, Buck, I had to read it a few times. My coffee cup Load Cell is STILL working just fine in my workshop and the beauty of it is that it is simple. It "just works".

[@buckstarchaser2376]

@@RalphBacon Moving it to another place once it's empty would "just work". Putting one of those "blind spot mirrors" from an auto-parts store on the underside of the cupboard above the cup would work also, since you could see the bottom of the cup. But... Imagine, if you will... A glorious strip of laser beam that points to a hand-drawn scale that ranges between "E" and "F". The direct - and illuminated - approximation of vessel fullness (or emptiness, at your sole preference) would announce to all weary office wanderers, who's domain they're in - and more importantly - the level of His Majesty's coffee.

[@RalphBacon]

I could cheat and use an IR distance detector but also one (or more) of those "cat toy" type lasers you can get for Arduinos and use that to display the level using a stepper motor to change the direction of the beam. Sounds like something you'd find at a Geek Fair. In other words, fascinating but ultimately a little over the top. (Even more so than my Load Cell). I like the Blue Sky thinking, though.

[@buckstarchaser2376]

@@RalphBacon Point the laser at the coffee surface from above, but at an angle. The current volume will determine where the laser light falls, and just calibrate that area. If you want it overly complex, modulate the laser, use a cheap green one but filter out the green, leaving the IR that was used to create it. When the coffee level reaches "low", the reflected, modulated, IR laser turns on the coffee maker.

[@hongcheong5294]

香港头像

[@RalphBacon]

+Hong Cheong 您好香港头像。我希望你喜欢的视频。 Hello Hong Kong Avatar, I hope you enjoyed the video. (courtesy Google Translate!).