Magnetostrictive Position Sensor

Do you want to build a Magnetostrictive Position Sensor as described in:
https://de.wikipedia.org/wiki/Magnetostriktiver_Wegaufnehmer

In short: A current pulse will initiate a torsion wave along a magnetostrictive wire at the position of a moving cursor magnet. The travelling torsion wave generates a signal in a receiver coil. From the time between current pulse and the signal pulse the position of the magnet (the distance between receiver coil and magnet) can be determined.

Note: Current development and discussion can be found here:
https://hackaday.io/project/202298-magnetostrictive-position-sensor
Here you can also read more about signal recording schemes and alternative counter electronics.

Here is a set of parts to build a Magnetostrictive Position Sensor.
With this sensor you can measure the position of a magnet sliding along a PVC tube surrounding a magnetostrictive Nickel wire.
You can use it to build a linear servo with a DC motor. The sensor is scalable as working range