Measuring voltage of any material

Projects General Guidance
1

Basically I want to use Arduino UNO to measure voltage over resistors, random metals and even liquids?
How can I do it and what do I need?

2

For voltages between 0 and 5V:

Otherwise, use your multimeter.

3

The analog inputs of an Uno cannot tolerate any voltage over Vcc + 0.5V nor ground - 0.5V. The protection diodes cannot handle more than 1mA. So there must be components that keep the voltages and currents within those specifications.

The ADC (Analog to Digital Converter) is 10 bits so each bit represents Vref / 1024 Vots (0.00488V @ Vref = 5V, 0.00107V @ Vref = 1.1V). If more precision is needed an amplifier is necessary.

What is the maximum sample rate requirement? For maximum resolution each sample takes about 110us. That does not take into account saving the sample data to memory or where ever or any processing of the
data (ex. FFT).

Uno analog inputs are ground referenced and single ended so cannot, directly, measure the voltage across something that does not have one end grounded.

If you want more precise advice, ask a less ambiguous question. What voltages? What materials?

4

Like measuring the voltage of a fork, coin, wire, etc.

5

Usually zero.

6

An ADS is not needed?

7

How do those things have a voltage? Voltage is the measurement of the potential difference between 2 points. In the case of a coin, for instance, where are those points. I ask the same of the fork and wire.

I am sorry, I am having a failure of imagination. I am not being critical, I just do not understand what you are trying to do.

8

Not to measure 0-5V with Arduino.

9

I want to measure electrical conductivity of materials, I used this method https://www.instructables.com/Will-It-Conduct-Electricity-With-Arduino/, I thought it measured electrical conductivity directly, but I think it measures voltage, right?
It really doesn't say what the values are.

10

Electrical conductivity is the reciprocal of electrical resistance. Simple math.

11

What about it, how would you measure electrical resistance lol.

12

See posts #2 and #3.

13

To measure voltage over resistors, metals, and liquids with an Arduino UNO, you will need some additional components. Here are the steps to get started:

  1. Get an Arduino UNO board and a breadboard to assemble the circuit.
  2. Add a voltage divider circuit using a fixed resistor and the element (resistor, metal, or liquid) you want to measure the voltage across.
  3. Connect the voltage divider circuit to the Arduino UNO board, with the fixed resistor connected to a digital pin and the element connected to the analog input pin (A0-A5).
  4. Write a sketch (code) to read the voltage from the analog input pin and convert it to the corresponding voltage value. You can use the built-in analogRead() function to read the voltage and map() function to convert the reading into a meaningful value.

Here's an example circuit diagram and code to measure the voltage across a resistor using an Arduino UNO:

Circuit Diagram:

yamlCopy code

      +5V
       |
       R1 (10k ohm)
       |
       |
       |
       V
       |
       |
       |
      A0
       |
      GND

Code:

scssCopy code

void setup() {
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(A0);
  float voltage = sensorValue * (5.0 / 1023.0);
  Serial.print("Voltage across R1 = ");
  Serial.print(voltage);
  Serial.println(" volts");
  delay(1000);
}

In this example, we are measuring the voltage across a 10k ohm resistor connected to the analog input pin A0. The voltage reading is converted to a corresponding voltage value and printed to the serial monitor. You can modify the code to measure the voltage across different elements by changing the circuit and the analog input pin.

Measuring the voltage of a fork, coin, wire, or any conductive material can be done using an Arduino UNO board and a few additional components.

Here are the steps you can follow:

  1. Connect one end of the material you want to measure the voltage of to the analog input pin of the Arduino. Connect the other end to ground.
  2. Add a series resistor to limit the current flowing through the material. The value of the resistor will depend on the voltage you expect to measure and the resistance of the material. A good starting point is to use a 10 kΩ resistor.
  3. Write a sketch that reads the voltage on the analog input pin. To do this, use the analogRead() function to get a value between 0 and 1023 representing the voltage. Then, convert this value to a voltage using the formula: voltage = analogRead(pin) * (5.0 / 1023.0);, assuming that you are using a 5V Arduino board.
  4. To measure the voltage of liquids, you can use a pair of metal probes to immerse in the liquid. Make sure to isolate the probes from each other and connect one probe to the analog input pin of the Arduino and the other to ground.
  5. It's important to note that the voltage measured may not be accurate due to factors such as contact resistance and oxidation of the material. To improve the accuracy of the measurement, you can calibrate the system by measuring a known voltage and adjusting the calculation accordingly.
  6. Finally, you may want to add additional components, such as a filter capacitor or a voltage divider circuit, depending on the specific application and the voltage range you expect to measure.

Keep in mind that measuring the voltage of conductive materials can be dangerous, especially if you are dealing with high voltages or currents. Take appropriate precautions and use a multimeter to verify your measurements before making any decisions based on the readings.

14

Google "how does an ohm meter work".

Google "arduino resistance measuring"

The thing with your project is that the resistances measured are going to be very low, much less than 1 Ohm. That is very hard to do accurately. Look here for some pages on that subject, "measuring very low resistance".

And some pages on "measuring low resistance with Arduino".

15

If ine probe isn’t at zero, and you want to get ‘clever’, you could use two analog inputs, read them at the same time and measure the difference between them

16

To answer you need to know what range of voltage are you expecting?

Using the internal reference the lowest the UNO can go is.

0v then the next step is about 1 mv. The input cannot measure 1/2 mv.

17

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