I need some help about my current project. I am trying to do a voltage source which can be controlled remotely(0V-20V). I am using LM317T for this project. I examined the LM317T datasheet and designed a circuit for a 10k potentiometer.enter image description here

After setting up the circuit, I tried the circuit with the analog 10k potentiometer and the results were fine.( I get 1.25 V to 19.5 V). After that I have tried to control X9C103 with Arduino UNO and again the results were fine. Here the codes.

#include <FastX9CXXX.h>
#define X9_CS_PIN 3
#define X9_UD_PIN 4
#define X9_INC_PIN 5

FastX9C103 Potentiometer;
String readString = "";

void setup() {
  Serial.println(F("ESOGU Uzaktan Laboratuvar"));
  Serial.print(F("Digital Potentiometer Application..."));
  Potentiometer.Setup(X9_CS_PIN, X9_UD_PIN, X9_INC_PIN);
  Serial.println(F(" Completed."));


void loop() {
  Serial.print(F("Potentiometer (%): "));
  Serial.print(Potentiometer.GetStep(), DEC);
  delay(1000);    // wait for a second

     if (Serial.available() > 0) {
       while (Serial.available()) { // gelen komutu alıyoruz
       char c = (char)Serial.read();
       readString += c;

But after implementing digital potentiometer to my circuit. I didn’t get the results that I want. I got 1.5 V to 7 V. The circuit is working perfectly fine with analog 10k potentiometer but not with 10k digital potentiometer. Thank you for your answers.

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