I find life is good with an in-ear Clarity Aloft headset that has no batteries and does not need noise cancellation. It’s a bit delicate but you do figure out how to use it and don’t have to worry about Auto-anything. The sound quality is also better than other headsets I’ve used.
Presumably that’s because in order for it to detect when it’s connected to a radio/intercom, the electronics would need to be permanently powered to know when to fully turn on.
That is easy enough. Many years ago I designed a product which released fire doors to auto close upon “hearing” a fire alarm. It used about 10 microamps. And years before that I designed an underwater device which listened to a coded audio signal; that had to run for several years and the job was achieved by having an ultra low power timer (under 1 µA) which turned on the main circuit for 1 second every few mins.
