Positek Linear Transducer

Experts in standard and custom linear transducer design


There is a wide array of position sensors available in the market today. Each type of sensor has a specific application. One of the most commonly used position sensor is a Linear Variable Differential Transformer, also called linear transducer.

What is a Linear Transducer?

The working principle of a linear transducer is to convert an objects linear motion into electrical signals. This provides the machine with workable data that is used in its overall function. Linear position sensors can measure movements of as small or as few as millionths of an inch up to several inches. There are sensors that can also measure up to ±30 inches (±0.762 meter). Linear transducers are characterised by several components which are:

  • Primary Winding
  • Secondary Windings
  • Core (threaded hole on both ends, high permeability nickel-iron core)
  • Epoxy encapsulation
  • Stainless steel housing and end caps
  • High permeability magnetic shell
  • High density glass-filled Polymer coil form

These components provide the basic structure and working parts of a linear transducer.


What does a Linear Transducer do?


Linear position sensors are used in many industrial and mechanical applications. Here are some examples of where transducers are commonly used:

  • Automation. This is the most general application of transducers. Since linear sensors are hermetically sealed, it can perform beyond laboratories and workshops. Linear position sensors can be used in harsh environment applications such as factory automation, and industrial gauging.
  • Hydraulics. Linear sensors serve as charge sensors in hydraulic accumulators.
  • Cylinder Position Sensors are specifically used in hydraulic and pneumatic applications.
  • Power turbines. Power plants make sure of power generation turbines. These turbines need a Position Sensor with signal conditioners to provide the necessary power.
  • Aircraft and aviation. The vast majority of aircraft require a linear transducer to measure wing deflection. Manufacturers like Positek develops precision sensor products to be used in commercial aircraft, and space aviation systems such as communication satellites.

How does a Linear Transducer work?

A typical linear transducer consists of three seleniod coils lined end to end, surrounding the tube. The primary coil is found in the centre and secondary coils are on the top and bottom. The object which position will be measured is attached to the cylindrical ferromatic core, and slides along the axis of the tube. The primary coil is driven by alternating current using voltage induced in the two secondary coils. Frequency range is anywhere between 1 to 10 kHz.

The core’s movement triggers from the primary coil to both the secondary coils, which changes the induced voltage. The movement from calibrated zero phase is defined by top and bottom secondary output voltage differential. Linear transducer displacement can be up to several inches long. This will then work as an absolute displacement sensor with repeatable and reproducible results. New innovations in linear sensor technology produces sensors that are in a completely sealed environment. This has the added benefit of preventing contact between the core and other parts of the mechanism.


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