actionyann t1_jdqzu01 wrote on March 26, 2023 at 2:42 PM

Wired headphones to a cellphone, (like wired speakers to a stereo player) get the electric signal from the cable in an analog way, it contains both the energy and the signal.

That is enough to move the magnet&membranes in the speaker and reproduce the sound.

But for wireless speakers, the wireless signal does not transfert [enough] energy. And the headphone needs a source of electric power to : run the Bluetooth receiver/sender, and move the membrane to produce the sound.

[Edited to add remark]

Target880 t1_jdr1lf1 wrote on March 26, 2023 at 2:55 PM

>But for wireless speakers, the wireless signal does not transfert energy.

It does transfer energy is just not enough to power the amplifier or to directly drive the membrane.

RFID is an example of short-distance radio communication where the signal powers the tag. Contactless payment with credit and debit card use RFID to power chips that do encryption to make it safe.

You could have a transmission on one to power the headphones it would just be very wasteful of the phone battery. There is an audio transmission system that can and just that. You can build a crystal radio to receive AM radio and it does not need any power source.