LINEAR VARIABLE DIFFERENTIAL TRANSFORMER

The goal of this project was to build a distance measurement device. We decided to build an LVDT to make a set of calipers. Using an Arduino, a 555 timer, and some curve smoothing circuitry, we were able to generate a relatively sinusoidal waveform. This was amplified, then passed through an isolation transformer and into an inductor. The signal was transferred to a second inductor inside the first one. The signal then traveled to a pick detector where it could be interpreted by the Arduino. What made this work was that within the two inductors was a two piece metal rod, made of aluminum and iron. The permeability varies between these two materials, so the amplitude of the signal transferred between inductors varies as the material inside the inductor changes. We were able to use this rod as a caliper system, then calibrate the Arduino within the linear region to attain a reading correct to within +/-0.5mm. I am very proud of this project because of the amount of time spent on it. The professor was thoroughly impressed as we were the first group who were ever able to create a working LVDT that ran solely off an Arduino, and did not use an external power source or function generator.