2 Digital Potentiometer Circuits Explained | Homemade Schematic Diagrams. 2) Digital Potentiometer using IC X9315. In this second design we investigate the IC X9315 which is actually a solid state digital potentiometer and could be used exactly like a mechanical potentiometer, but through logical supply inputs. How to Build a Digital Potentiometer Circuit with a MCP4131 How to Build a Digital Potentiometer Circuit Using a MCP4131. In this project, we are going to show how to connect a digital potentiometer to a microcontroller so that we can control the resistance put out by the potentiometer in software. Digital Potentiometer - Working, Internal Structure Digital Potentiomter – Working, Internal Structure & Applications. One of the most common types of variable resistors is the potentiometer. Potentiometer or “pots”, are three terminal devices, used to vary the resistance in a circuit.