Hello, guys!
This is my first time to write a question. I apologize if I made a mistake.
I am working to make a loadcell-based weight monitoring system controlled by Arduino. In the beginning, I used a YZC-1B loadcell, an AD620 instrumentation amplifier supplied by a 9V and -9V battery, a first order passive low-pass filter, Arduino Uno R3 with 16x2 LCD display, and all supplied by LM317T regulated at 10V from a 19V 60W Toshiba laptop charger. The reasons why I chose 10V were, first, that value is recommended to supply the sensor as stated in the datasheet, second, since the maximum of LM317T's current is 1.5A, I thought it might work if I power the Arduino with that and, last, I needed to choose components as cheap as possible and easy to find with regard to the performance. It went well for the first time until I found some reasonable problems, such as:
- The ADC value still went up and down.
- Even though I have connected all of the reference nodes, different values of the reference will occur. I mean if I measure the output voltage of LM317T with respect to its reference (ground) node, it will give different values if I measure it with respect to the other references, such as the ground node of Arduino.
- Sometimes the output value of the sensor goes up and down for the same load and if I am lucky, it goes back to the start.
I have troubleshooted the first problem using a combination of exponential digital filter and moving average algorithm, and also have separated the supply between Arduino and the sensor using another LM317T, but the problem was just minimized. Sometimes the ADC value will change with AD620's output still remains. Fyi, this work is for charity. Accuracy is not my concern, but I just want this system stable.
Do you have any suggestions?
Thank you in advance.