[maemo-developers] N800 audio connector jack

[From: Jami Pekkanen]

Jami Pekkanen wrote:
> Kemal Hadimli wrote:
>> 1520 ohms.
>> headset button pressed it goes down to 47 ohms.
> 
> Thanks! I bought a multimeter and got similar values. The 40-50 ohms 
> seems to be the headset's (microphone's and speakers') internal resistance.
> 
> However, I now have a circuit (now just made of resistors) that has 
> almost identical resistances as the headset, but it still won't shut 
> down the internal microphone. Could there be some other magic that the 
> device is using to probe for the microphone?

Replying to myself here.

I continued figuring out the headset detection, and I (accidentally) 
noticed that the resistance is different depending on which direction 
it's measured. On another direction it's about 1.8 kOhms and when 
switching around the heads of the multimeter, I get ~1.1 kOhms. So now 
I'm guessing that the detection is perhaps somehow done by comparing 
this difference.

Unfortunately my knowledge in electric circuits isn't too vast and I'm 
having a hard time even imagining what kind of circuit could do this. 
Could someone with more experience in electrical systems shed some light 
on what could be happening here?

Thanks
- Jami