Wire drawn linear position transducers, also known as string pots, string encoders or yoyo pots are devices that detect and measure linear position by using a flexible wire and a spring loaded spool.

The transducer is mounted onto any fixed surface and the flexible wire attached to the movable target object. When the target object moves, the wire is extracted from the transducer, which in turn generates an electrical signal proportional to the length of wire extracted from the transducer. This signal is then sent to a panel meter, PLC or data logger.

Wire drawn transducers consist of four main parts: measuring wire, spool, spring and rotational sensor.

The stainless steel wire inside the transducer's housing is wound on a precisely machined constant diameter cylindrical spool that turns as the measuring wire is extracted and retracted. The wire tension is maintained by coupling a spring to the spool, which in turn is coupled to the shaft of a rotational sensor (an encoder or potentiometer). The spool and sensor shafts rotate as the transducer's wire extends along with the moving target object, with the rotating shaft generating the electrical signal output. An integral dust wiper ensures the wire rope stays clear of debris as it is extracted and retracted.

UniMeasure offers a choice of commonly used industry-standard output signals: Potentiometric (Voltage Divider); 0...10 Volts DC; 4...20 mA (2-wire); 0...20 mA (3-wire); Incremental Encoder (Quadrature).

Wire drawn linear position transducers are designed as a simple solution to measure the position and movement of the target object. Easily installed, the transducers can be positioned in tight or difficult to access areas without requiring perfectly parallel alignment. Compared to other linear position sensing solutions, wire drawn transducers tend to be more cost-effective.

UniMeasure wire drawn linear position transducers deliver excellent linearity and repeatability at full scale, making them perfect for a wide variety of applications such as industrial automation, high-tech medical devices, structural and locomotive testing, and hydraulic cylinder control among many others. Measuring ranges in the UniMeasure devices are available from 0-50mm, all the way up to 0-50.8m.

UniMeasure wire drawn transducers are available in Australia from ADM Instrument Engineering .