SMD linear potentiometric displacement transducer in the bare resistor, pressing one or two removable metal contacts, contact position to determine the resistance between the resistor and the contact between the end of the resistance. When a voltage is applied between the two fixed contacts of the resistor body, the position of the contact on the resistor is changed by rotating or sliding the system, and a contact point between the rotary contact and the fixed contact is obtained, A certain relationship voltage.