I/O Control Voltages Survey

Well this is the "control geek" blog, after all...  Years ago, in our Gravesend Inn haunted hotel, we started adding pneumatic effects on a shoestring budget. I needed a low-voltage driver for electromagnetic pneumatic valve coils, and since an AC transformers (in those days) were cheaper than decent DC supplies,I just ran everything on 24VAC. That also had the side-benefit of less problems with inductive kick-back spikes, etc.

So now, the show has grown enormously, and over the winter we'll be revamping the system. I'm wondering, what's the most widely used I/O voltage? As a school coupled tightly to the professional market we want to follow industry practice as much as possible. So, of course, I made a survey: https://www.surveymonkey.com/s/7BXXMML

Anyone who works with this stuff, please take this survey before noon on Friday 10/5. It will only take about a minute to fill out. I'll post the results when I get them tabulated!