How do buttons on earphones work?

How do the buttons on wired earphones work? It is not immediately clear since the 3.5mm plug has just four connections, and they're already used by the left and right audio channels, the microphone and the common ground.
But on Android devices, a simple voltage divider circuit is used to send different voltages to the microphone pin when a button is pressed. Different voltages are interpreted as different commands. Clever!
#electronics #buttons #diy

[@Jiyoon02]

The moment you said "voltage divider" it clicked and made sense.
It's such a simple technique, but I like it when engineers solves a seemingly complicated problem with an simple and creative solution that just works.

[@LeftyMaker]

I think that if you pick the resistor values carefully, you can even make the buttons work when pressed at the same time. I'll probably give it a try one day

[@hrld0]

​@@LeftyMaker Please give it a try today! I'm waiting for such contents. Thank you

[@geoffmooregm]

This goes way way back. I remember my ond Discman had similar controls on the wires. It only had 2 contacts on the minijack, but I would assume it worked in the same way.

[@LeftyMaker]

It is likely, although I remember those Sony Diskmans having additional connectors - maybe 4 or so lined up on the outer side of the jack

[@gentleclash]

I used to think that they short the ground with other 3 pins for the function.

[@OculuKabak]

guess what, some headphones (1 button) short microphone with the ground

[@apaltado]

so interesting!!!! great video

[@IND3CISIV3]

So that’s why the apples buttons don’t work with my laptop 💀

[@OculuKabak]

that really depends on audio interface and the OS

We need to fix the 4p 3.5mm plug. Mic and gnd need to be swapped.

[@LeftyMaker]

I think I've seen adapters for this

[@OculuKabak]

why?

[@stefan-bayer]

How does it Apple with their EarPods?

[@Traper_T]

Wire less digital strem of data it's nothing special to put in couple bits to volume control

[@OculuKabak]

bluetooth data

[@georgefloydtv.]

EARpods not AIRpods

[@kreuner11]

​@@Traper_T no! the old wired ones

[@Traper_T]

@@kreuner11 ok I forgot times when apple was adding earpods but wasn't that similar volume system or they have to use something different and non compatible like ussula?

[@garretreed9709]

I want to understand this but don’t know electrical jargon

[@aerohk]

So the audio input volume would drop when the button is pressed?

[@cryingwater]

You would hear a click

[@orln]

Does the mic work while the buttons are pressed

[@rouuuk]

But how can the mic still work perfectly with the buttons pressed?