24V Potentiometer

Other Hardware General Electronics
1

Hello everyone,

I have a potentiometer that can operate up to 28V. I'm attempting to use it as an extensometer. Initially, I tried using it with an Arduino Uno powered at 5V, but I realized it wasn't very accurate. Now, I'm supplying 24V to the potentiometer with a power supply and dividing it down to 5V using a voltage divider, as shown in the circuit diagram. I then connect the 5V divided output to A0 on the Arduino. However, when I measure the voltage between A0 and ground, it's approximately 8.6V. I expected to measure 5V, but it's more than that. However, in the disconnected state, the pin reads 5V as expected.

I tried adjusting the voltage from the power supply until I have 5V between A0 and ground in the connected state. However, even after doing so, I still cannot see the sensor values on the Serial Monitor.

What am I doing wrong?

POTI_CIRC
POTI_CIRC1532×671 23.1 KB

const int potPin = A0;

void setup() {
  // Starte die serielle Kommunikation mit einer Baudrate von 9600
  Serial.begin(9600);
}

void loop() {
  // Lese den Wert vom Potentiometer aus
  int sensorValue = analogRead(potPin);

  // Drucke den Wert auf der seriellen Schnittstelle
  Serial.print("Potentiometerwert: ");
  Serial.println(sensorValue);

  // Warte einen kurzen Moment, bevor der nächste Wert gelesen wird
  delay(100);
}
2

First, are your grounds connected? People often use the same ground symbol in different parts of their circuits, but IRL they end up not being connected.

3

The 8.6 may have damaged the input. Try a different analog input, if that doesn't work, try another Uno/Nano.

4

it worked thank you. But why they should be connected together? ground is ground aint it? :smiley:

5

Hello bengimehm

Take a piece of paper and calculate the values of the voltage dividers.

6

you mean that the values are not linear?

7

Haha, no. Think about it - I have two circuits in front of me with no wires connecting them.

If I call one point in one circuit "ground", and a point in the other circuit "ground", by what magic or sorcery do these two things know the least thing about each other?

In this context, ground is just… a point in a circuit that is convenient to call ground. Like the negative end of the power supply. Very handy to have a common (see?) wat to refer to that, so it can be used all over your circuit as a substitute for a line drawn alla way back the the battery.

a7