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Need help with arduino sampling voltage and current

  1. Jan 22, 2013 #1
    Hi, I built a electrolytic cell that uses electricity to break water into hydrogen and oxygen. I am testing efficiency and need a way of calculating the average current draw and voltage drop over a period of time for the cell. I have some experience using Arduinos in projects but not much. I know I will have to take samples then use a function to calculate the average voltage and current. By the way the current is measured using a shunt so 1mv = 1amp. The voltage drop averages around 40 volts. I have researched some but am still very confused on adding memory to the arduino and outputting data via serial cable to a laptop. Any help would be much appreciated. Thanks in advance.
     
  2. jcsd
  3. Jan 23, 2013 #2
    Sounds like you want to do some analog input sampling. Remember the Ardunio can only measure inputs between 0-5V, so you want to design a circuit with a voltage divider and some diodes to ensure that the input to the Arduino never exceeds the value it can take (trust me, you'll fry the thing if you don't).

    Have a look at this one:
    http://fritzing.org/projects/voltage-divider/



    As for the actual analog signal sampling, the Arduino is very useful and userfriendly. Have a look at the analogRead() function:
    http://blog.littlebirdelectronics.com/tutorial-arduino-and-the-aref-pin [Broken]
    http://arduino.cc/en/Reference/analogRead
     
    Last edited by a moderator: May 6, 2017
  4. Jan 23, 2013 #3
    Thanks for the reply, I now understand how to read the voltages with the arduino, but I don't totally understand the serial functions that are used to output the data that is recorded. I understand that I can use the Arduino environment to process this serial data input but I was wondering if you know a good way to maybe make a graph out of the data. Again thanks for all of your help.
     
    Last edited: Jan 23, 2013
  5. Jan 24, 2013 #4
    No worries!
    Well, what serial functions are you using at the moment?

    An easy, but slow, method that I sometimes use when I need to graph data is to use the Serial.println( ); function, and then simply graph the data I get versus time in some other software (Excel)
     
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