Technical Blog

More About Linear Transducers

At Positek, we are experts in standard and custom linear transducer design.

There is a wide array of linear position sensors available in the market today. Each type of sensor has a specific application. One of the most commonly used position sensors is linear transducers.

What is a Linear Transducer?

A linear transducer measures the displacement of an object along a single axis. They are used to convert objects linear motion into electrical signals. This provides the machine with workable data that is used in its overall function. Linear transducers can measure movements as small as millionths of an inch up to several feet.

Our Linear transducers are characterised by several components which are:

  • Sensing coil.
  • Plunger or target tube mage from non-magnetic metal.
  • Stainless steel housing and end caps

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


What does a Linear Transducer do?

Linear transducers 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 well sealed, they 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 develop 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 solenoid 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 thats position will be measured is attached to the cylindrical ferromagnetic 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. The 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 phases 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. Innovations in linear sensor technology produce 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.
 

Positek sensors differ from other inductive sensors in that it only has a single sensing coil and the coil has very few turns of wire, typically 100 turns. In a linear sensor, the coils are wound on a former with standard enamelled copper wire. This results in a coil that can be very compact and, in turn, is very robust. It is possible to produce linear sensors with coils of only 1.5 mm diameter. With only a few turns the coil has very low inductance and with appropriate capacitor values, the natural frequency of oscillation of the LC circuit is set in the order of 1 to 2 MHz. The frequency is not specifically controlled and is allowed to vary as the target moves over the coil.

 

Linear Transducers from Positek

All of our linear transducers can be seen in the product section of our website, for more information or to discuss your custom requirements please contact us.

Article published on: 02/02/2022