Why Use an AC LVDT versus a DC LVDT Linear Position Sensor?
The introduction of high-density microelectronics enabled the incorporation of signal conditioning and processing functions inside the LVDT housing rather than requiring an external box. The DC-operated LVDT maintains all the desirable characteristics of the AC-operated LVDT, but has the simplicity of DC operation. It is comprised of an AC-operated LVDT and a carrier generator/signal conditioning module.
So why haven't DC-operated linear position sensors replaced the original AC-operated versions?