Listening devices can be passive, getting their energy from radio-waves beamed at them. A clever invention by the soviets that was actually used. It's also the concept behind RFID.
Most likely, these days, they will bug your phone though.
Devices that record to some kind of medium don't seem like a practical choice, since you'd have to regularly have access to it to get out the sd-card or whatever it records to. And once you're down that rabbit hole, it might just as well be battery powered.
Listening devices can be passive, getting their energy from radio-waves beamed at them. A clever invention by the soviets that was actually used. It's also the concept behind RFID.
Most likely, these days, they will bug your phone though.
ah that's cool. a recording device would still need some kinda power right?
Devices that record to some kind of medium don't seem like a practical choice, since you'd have to regularly have access to it to get out the sd-card or whatever it records to. And once you're down that rabbit hole, it might just as well be battery powered.
Ah interesting good point.