[gumby]

Thanks for that great message!

The case I was thinking about was specific to the airtag. In this case a fixed voice coil moves a small permanent magnet attached to the diaphragm rather than the other way around (according to iFixit, quote below). So maybe a rare earth magnet oriented the right way could prevent the magnet from moving. There’s an air gap so it will have to wait until I can do an experiment.

Note from iFixit:

> Did you notice the “button” on the underside of the cover? That’s not a clickable button, like the Mate and SmartTag have, but rather the magnet we saw earlier in the X-ray. It sits right inside the donut-shaped logic board, nested into a coil of copper to form a speaker. You read that right—the AirTag’s body is essentially a speaker driver. Power is sent to the voice coil, which drives the magnet mounted to the diaphragm—in this case, the plastic cover where the battery lives—which makes the sounds that lead you to your lost luggage.