[msds]

LVDTs are fun! I bought one for a project a few years ago (since abandoned), and have been slowly designing my own readout electronics for them. Three revisions later, and the performance is very good - to the point that I've bought more increasingly precise measurement gear to benchmark how it's performing. Currently, I'm testing it against some good glass scale linear encoders, and a capacitive gauge with a single-digit nm noise floor.

So many don't buy an LVDT, I guess.

[daveguy]

Interesting. What applications are you using it for? (If you are okay discussing it.) diy calipers? Active feedback to a more complex mechanical system? As part of an optical system? It would be interesting to hear how these are being used. Especially from someone experience using/building them.

[msds]

I was using it to build a dilatometer - an instrument for measuring thermal expansion curves of materials. Theoretically simple, in that you take a sample of something and measure how long it is while sweeping the temperature around. In practice, you need very stable ~um measurements and lots of care to make sure all other length changes around the sample cancel.

In the real-world, they're often used for precision gauging for in-process metrology.