IMO anything with unnecessary digital interfaces is already down the path.

I have a Vornado fan that I would love to automate with a simple wifi-enabled plug, but due to the digital on/off/speed button, when you cut-off and restore power to the device, it stays off. If it had a dumb analog dial or switch, it would both be fine for normal use, and could be easily, cheaply made "smart."

They do sell wifi-enabled fans; none of them are in a form factor that would fit in my window.

I'm not even alone in this gripe, lots of other maniacs have done the hard work of conversions. Unfortunately I'm not confident enough in my soldering skills to try :\ https://www.reddit.com/r/electrical/comments/vaiskf/bypass_p...

Could tie it to a thermometer and turn it on automatically on hot days. Very cool.

Based on the description of the wiring to the motor (24V, GND, POT1, POT2, NC), it doesn't sound like the original setup would have been drawing much power through the pot either -- there's probably something else on the other end of that wire that is doing modulation based on the sense resistance, and the motor is itself drawing power from the 24V line. So while it's true that there should be a check for the allowable limits on the digipot, I don't think it's actually being used to sink much power.

Hey, author here. There's a line in the digipot datasheet that says the voltage on the A/B/W pins must be within -0.3V to VDD + 0.3V. The fan's line for the wiper pin is 5V, which would fall well outside of that if I gave the digipot's VDD 3.3V.

Depending on your air filter you might be able to just use a smart plug, I went down a similar route this summer before realizing that mine would remember their power state and settings when powered off.

So now I just have them plugged into a few smart plugs with automations in homeassistant