[maemo-developers] N800 audio connector jack

[From: Kemal Hadimli]

Should try 1n4148 as the diode, although I can't offer much help/ideas
other than that. Very limited electronics knowledge.

You can salvage 1n4148 or alikes from any radio or scrap pcb lying
around. Look for the tiny orange-ish[1] diodes.

[1] http://www.eleinmec.com/figures/029_02.gif

On 9/8/07, Jami Pekkanen <jami.pekkanen at tkk.fi> wrote:
> Jami Pekkanen wrote:
> > Continuing my monolog.
> >
> > I came to think to me that this could be done with a diode.
> > Unfortunately my knowledge in them is even worse than with resistors.
>
> I took some lessons from Wikipedia and came up with a circuit diagram
> that could give similar resistances than the headset:
>
>       --- R1 -----
> +   |            |
>   ----- V1 -- R2 ----
>                      |-
>                      M
>                      |+
>   -------------------
> -
>
> Where R1 is 1.8 kOhm resistor, R2 is 2.7 kOhm resistor, V1 is a diode
> and M is the plugged in microphone. The diagram may be wrong way around,
> but the idea is that to one way the circuit has ~1.8 kOhm resistance and
> to another ~1.1 kOhms. However, at least my diode (1N4004) seems to have
> too high set-on voltage for my multimeter's ohmmeter while the headset
> can be measured OK, so I can't verify the results with it.
>
> Also I noticed that there seems to be two inductors, one semiconductor
> and a small resistor (50 Ohm) in the headset and there's probably a
> bigger resistor in the push-button. There also was some component
> between the microphone's pins which I assume is a conductor for the mic
> (I lost the component). Also I can't get any readings of the
> semiconductor (it's marked V01, which would say it is one) and I have no
> idea how to measure specs of the inductors. However, I'd guess that the
> circuit has some kind of transformer for the microphone, which could
> also lower the set-on voltage of the diode.
>
> So to put the above together, I have mostly faint guesses how the system
> may work and any advice from people with more knowledge in electronics
> would be very appreciated.
>
> PS. This seems to drift quite a bit away from the list's topic, so feel
> free to tell me to shut up when you get enough of these ramblings ;)
>
> - Jami
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-- 
Kemal