hi…my group idp want to create a floor mat alarm clock that using arduino uno and load cell, what type of load cell that can be use to measure the human weight and how to connect to arduino?
@Thierry: Other than the RB-Onl-38 (analog output), we have the RB-Dfr-519 (digital output, 2 wires) and the RB-Phi-107 (USB) with an app (RB-Rbo-176).
@aida: Considering the complexity of this question, we recommend that you instead post about this on our forum instead. As for the load cell selection, simply make sure that the load cell can be used in that range of weight.
hi… im anthea from malaysia… im proposing a project for my final year project. im wanna use a suitable sensor to be allocated in optimal slot in vending machine to prevent determining restock due and sold out problems. examples, im allocating this sensor on the 4th slot, when a person purchase the item, it may detecting the 4th slot is empty and it is connected to the business inventory system. and when its occur, the business may alert of restock activity or sending a notification for restocking activity. i wanna know what is the most suitable sensor should i use to detecting the presence of the beverages. so far, i decided to use load cell sensor 0-5kg… but if u may suggesting a suitable sensor, i will be pleased… thank u… 
@anthea: The load cell may not be a good solution, as it does suffer from creeping. This means that over time, if under load, the load cell will continuously report a higher value until the error is reset (unloaded and recalibrated). A simpler solution could be based on IR sensors, such as a IR range sensor or a proximity sensor (IR or physical). A simple one to use would be RB-Dfr-308 or RB-Tam-71. The use of a physical switch or an IR based one really depends on the shape of your products you wish to monitor and what space is available for the sensors themselves.
I have a torque cell that has 6 pins + EXCITATION, + EXCITATION SENSE, - EXCITATION SENSE, - EXCITATION, - SIGNAL, + SIGNAL , Can this load cell amplifier shield be used to interface the load cell to the arduino?
@chris: Cells usually come in two types of wiring, 4 or 6. The basic 4 wires are excitation + / - and signal + / -. The 6 wire ones also include sense + / -. These two extra wires allow you to check the voltage at the load cell in case there is a voltage drop between the power supply and the excitation received by the load cells. This allows you to rectify the issue by increasing the excitation voltage or amplifying the received signal to compensate. In the case of the RB-Onl-38, you will not need the sense + / - wires. Simply follow the documentation available here.
Hello, can Arduino connect the load cell and stepper motor. I need help here. Please respond… Thx
@meetMe: You cannot connect an Arduino directly to a load cell or stepper motor. To connect to a load cell, you will need a Wheatstone bridge amplifier, such as the RB-Onl-38 or the RB-Dfr-519. To connect to a stepper motor, you will at least need dual H-Bridge circuit, either from a dual channel DC motor controller or a board specifically made for stepper motor control.
Hello.
I hooked up the RB-Onl-38 with Arduino Uno with the 1kg load that came with the amp. I also has bunch of other load cells that I plan to use. Can you clarify a little bit more on how to get the maximum dynamic range out of the cell & amp? Is it possibly to get a integer 0 with zero load and integer 1023 with maximum load when reading analog input of the Arduino?
About the gain potentiometers. Should I apply half of the maximum load to a load cell and then turn the potentiometer so that it get around 511 when reading Arduino analog input?
Big Thanks in advance!
Tapio
@Tapio: For an example using a small load cell, the RB-Onl-38 and performing basic calibration, we recommend that you check out this article and the related Arduino library here (direct ZIP download). To maximize the range, we recommend that you connect your Arduino AREF pin to the 3.3 V DC pin, since the RB-Onl-38 excites the cells at 3.3 V DC, not 5 V DC. Then, in your code, change the ADC voltage to the external AREF (or internal 3.3 V, if available). You could also add a decoupling capacitor between the AREF and GND pins to reduce noise on the voltage source. For the gain, you should set the gain of your Wheatstone bridge amplifier so that an ADC value of 0 is as close as possible to no load and an ADC value of 1023 is as close as possible to your maximum load (but always a bit lower, since there will be creep if you leave it loaded for long periods of time).
I want to use the RB-Onl-38 with an arduino due which is a 3.3V based arduino (unlike the 5V uno) and can be easily damaged if a0 or a1 go above 3.3V (3.6V actually). It sounds like in the above post I shouldn’t worry too much because the 3.3V aref signal will somehow tell the RB-Onl-38 to go no higher than 3.3V? Is that right? I’m nervous using this without a schematic. Also if I leave strain2 disconnected won’t the amplifier slam to one rail (or maybe oscillate between both?) which also makes me nervous it might go over 3.3V. I’m more concerned with damaging the due by accident than anything else. So 1) Will the voltage be constrained below AREF? 2) Is there a schematic?
@George Roberts: The RB-Onl-38 actually only excites the cells at 3.3 V DC and the instrumental amplifier chip on the product is also running off 3.3 V DC. The only component that uses the 5 V DC from the Arduino board is the LED on the shield, so it may not turn on if there is no 5 V available or dimmer if it is 3.3 V. Otherwise, the entire shield runs off 3.3 V DC. As for a schematic, there is no public schematic available for this product.
Please note that the AREF pin on the Arduino board is unrelated to the shield [RB-Onl-38] and is only used for the internal ADC’s voltage comparison (ceiling).
Excellent - that’s all I need to know, thanks. Should I post a link on this blog to my instructables project some day when my project is done?
@George Roberts: We recommend that you create a post on our forum project show case category or on our project-oriented website, Let’s Make Robots.
hi do you prefer to cnnect the load sensor to the rsberry pi? or do we can just continue by cnnect the aduino to the rasberry pi?
@Muhammad Izzuddin Isa: The RB-Onl-38 is meant for Arduino only. Also, the Raspberry Pi chip does not have an on-board ADC component. A simple solution would be to connect the shield to an Arduino and then connect the Arduino to the Raspberry Pi by USB.
Hello, i want to use a loadcell + shield as described above in a neonatal incubator to help vary temperature with change in body weight of the infant, can the load cell dictate a weight change of 0.001kg? also can a single load cell be used for this setup considering the infant will be lying down and finally where can i order for this materials?? thank u
@Bubu: We strongly recommend against using hobbyist-grade electronics in such a function as they are not tested for reliability in such uses. Also, most load cells report their sensitivity on their full scale (FS) and it therefore varies with their maximum load. A typical load cell such as the RB-Phi-118 (datasheet) has a precision of 0.05% FS, which means roughly 2.5 g. Of course, the stability of the voltage source, the amplifier used and the ADC will affect the quality of the final result. Also, in most uses of load cells, 3-4 or more are used to obtain proper readings against a load. Again, please note that these devices should not be used in any situation where someone’s safety is involved. They are hobbyist-grade components and not meant for such uses.
I have a question: I want to measure wind force on a propeller, so i want to plot small, fast changes in force. How fast is the shield able to get the new value? Is it as fast as Arduino, or does it do on board averaging? I would prefer to get the raw data and do my own averaging and filters.