Abstract: Presently available transducer systems provide analog electrical outputs portional to the linear displacement of an active element from the surface being measured. However, use requires that all or part of the surface be conductive. The present cartridge permits use of these transducers on any surface, conductive or not. It includes a tubular casing receiving both an active element portion of the transducer and a plunger formed of a conductive material. The plunger is reciprocally mounted with a compression spring normally urging it outwardly so that its tip end can contact and follow the surface to be measured. A set screw arrangement limits the plunger reciprocation. The length of the received portion of the transducer is precisely adjustable so that its active element can be disposed a precise spaced distance from the plunger when it is spring-pressed to its limit. As the plunger tip rides the surface being sensed its inward motion is limited by contact with the transducer end wall.