LVDT Making and Testing. IC555 As Oscillator and Mosfet IRF840 Used for Primary Excitation.

In this project I built and tested a LVDT. LVDT is linear variable differential transformer. In this article made the LVDT on a paper bobbin. I used A4 papers two no.s. I rolled them into cylindrical bobbin. I used ferrite cylindrical core as the LVDT core.

In this circuit the primary winding of the is connected with an oscillator. I used IC555 as an oscillator oscillating at 45 KHZ. The oscillator output is fed to mosfet and finally it is driving the transformer primary. The core of the transformer is a ferrite core which is moveable

The secondary of the transformer voltage will change with the core movement.

1. IC 555 1 no
2. 1K resistor 2 no
3. 0.01 uF capacitor 2 no
4. 220 E resistor 1 no
5. 10K resistor 1 no
6. Bread board 1 no
7. Jumper wires.
8. Mosfet IRF840 1 no
9. Heatsink 1 no
10. Ferrite core 1 no

The LVDT is made on a paper bobbin. The bobbin is made with A4 size paper. This is a cylindrical bobbin. The ferrite core is a cylindrical core that slides inside the bobbin. As the core slides the voltage on the LDVT secondary changes.

The primary of the transformer is 80 turns copper wire and the secondary also has 80 turns copper wire. The transformer is 1:1 transformer.

As we move the core up and down the voltage on the secondary winding changes.

As per results when the core is completely inside, the secondary voltage is 17.5 V AC @ 45 khz

When the core is 90% outside the transformer length, the secondary voltage is 5.5 V DC @ 45 Khz

Please watch the videos showing the core position and the output voltage.