String Pots / Draw Wire

String pots (String potentiometers), also called cable extension transducers, draw wire sensors or string encoders are a wonderfully simple concept for measuring linear position. The cable winds onto a spool which is sprung loaded converting linear measurement into rotation. This rotation is measured using a potentiometer or encoder which is in turn converted to an analogue or digital output. They are easy to install, no critical alignment is needed and makes a direct measurement at the point of interest. A wide variety of options in regards to cable actuated, string pots, draw wire type sensors to cover many applications for lengths beyond 50 metres. Each data sheet has many options to cover your application for structural testing, automotive testing, civil/structural or even OEM requirements such as boom arm, elevators and outriggers.

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Frequently Asked Questions About String Potentiometers

A string potentiometer, or draw wire sensor, is a linear position sensor that measures the displacement or movement of an object. It consists of a retractable wire or string that is attached to the object being measured, and a potentiometer or encoder that converts the linear displacement into an electrical signal.

A string potentiometer works by extending or retracting a wire or string connected to the measured object. As the wire is pulled or released, the position of the object changes, and this change is converted into an electrical signal. The potentiometer or encoder detects the movement and generates an output voltage or digital signal proportional to the displacement.

String potentiometers are commonly used in various applications that require linear position sensing. Some common applications include industrial automation, robotics, machine tools, automotive testing, material handling, and motion control systems.

String potentiometers offer several advantages, including: Non-contact measurement: The wire does not physically touch the potentiometer, reducing wear and tear. Long measuring range: They can measure large linear displacements, typically up to several meters. Compact and lightweight: They are relatively small and lightweight, making them suitable for space-constrained applications. Cost-effective: String potentiometers are often more affordable compared to other linear position sensing technologies.

Yes, some string potentiometers are designed to withstand harsh environments. They may have features such as sealed enclosures or protective coatings to protect against moisture, dust, vibrations, and temperature extremes. It's essential to choose a sensor specifically designed for the environmental conditions of your application.

The installation process may vary depending on the specific sensor and application. Generally, the wire or string should be securely attached to the measured object, and the potentiometer should be mounted in a stable position. Some sensors come with brackets or mounting holes for easy installation. Always refer to the manufacturer's instructions for proper installation guidelines.

Yes, string potentiometers usually provide analog or digital outputs that can be interfaced with a variety of devices and systems. Analog output can be connected to an analog input of a PLC, data acquisition system, or controller. Digital outputs, such as quadrature signals or serial communication protocols, can be used for precise position feedback or integration with a control network.