Devices

The general schematic for this class.

Voltage

Separating Charges



      /*
        AnalogReadSerial

        Reads an analog input on pin 0, prints the result to the Serial Monitor.
        Graphical representation is available using Serial Plotter (Tools > Serial Plotter menu).
        Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

        This example code is in the public domain.

        https://www.arduino.cc/en/Tutorial/BuiltInExamples/AnalogReadSerial
      */

      // the setup routine runs once when you press reset:
      void setup() {
        // initialize serial communication at 9600 bits per second:
        Serial.begin(9600);
      }

      // the loop routine runs over and over again forever:
      void loop() {
        // read the input on analog pin 0:
        int sensorValue = analogRead(A0);
        // print out the value you read:
        Serial.println(sensorValue);
        delay(1);        // delay in between reads for stability
      }
    

Analog/Digital

Actually, we'll be measuring what portion of 5V is applied across the analog input.

Since it's a digital measurement (we'll come back to this), it will appear as a value between 0 and 1023.

0 means 0 V

1023 means 5 V

This is set by the 'resolution' of the system.

A microscopic view of a connected battery

The simplest circuit

The voltage divider

The Voltage Divider circuit is the easiest way to measure an unknown resistance. It has some limitations, but will essentially work for many applications $$ V_{\mathrm {out} }={\frac {R_{ref}}{R_{unknown}+R_{ref}}}\cdot V_{\mathrm {in} }$$

Measuring an unknown resistance.

Resistance

What affects resistance?