Re: N800 audio connector jack
Jami Pekkanen wrote: 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? 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. - Jami ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
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 ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
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 ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
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 [EMAIL PROTECTED] 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 ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers -- Kemal ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
I know of a pinout for a very similar device: http://web.it.kth.se/~maguire/iPAQ-photos/iPAQ-audio-adapter.html Thanks! That confirmed my info about the pinout. The PDF was quite in depth. Gopi Flaherty wrote: On Sep 4, 2007, at 7:24 PM, Jami Pekkanen wrote: Perhaps measuring the impedance of the headset first, then putting resistors on to your device, and then taking them off one by one to see which was necessary would work? I came to conclusion also, that there must be a resistor (after day of hacking, I'm not too great in electronics ;). Unfortunately I don't have a multimeter handy. Could somebody do a favor and measure the impedance between the third and the fourth pole (counting from the tip) of the headset's plug? - Jami ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
1520 ohms. headset button pressed it goes down to 47 ohms. happy hacking. On 9/5/07, Jami Pekkanen [EMAIL PROTECTED] wrote: I know of a pinout for a very similar device: http://web.it.kth.se/~maguire/iPAQ-photos/iPAQ-audio-adapter.html Thanks! That confirmed my info about the pinout. The PDF was quite in depth. Gopi Flaherty wrote: On Sep 4, 2007, at 7:24 PM, Jami Pekkanen wrote: Perhaps measuring the impedance of the headset first, then putting resistors on to your device, and then taking them off one by one to see which was necessary would work? I came to conclusion also, that there must be a resistor (after day of hacking, I'm not too great in electronics ;). Unfortunately I don't have a multimeter handy. Could somebody do a favor and measure the impedance between the third and the fourth pole (counting from the tip) of the headset's plug? - Jami ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers -- Kemal ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
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? - Jami ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
N800 audio connector jack
Hello, This isn't exactly maemo specific question, but I think this is the best forum anyway. I'm trying to solder together an adapter that splits the N800's 4-pole audio plug to two separate 3.5 mm females so that I can plug in separate input and output devices, eg electric guitar input and amplifier output (with maemo doing effects in between). So I took apart the headset that comes with the device and got the output part working fine, but I don't seem to get any signal to the input. In fact the device even doesn't switch the internal microphone off when I plug the modified system in. I'm assuming that there's two grounds (golden wires, another without coating), left output on a red wire, right output on green and input on white. The guesses were right for output, but as I said, the input doesn't get any signal at all. Is it possible that something special is required in the input connection? There at least seems to be some resistors in the headset's circuit, but I assumed they are just for the push-button. Also does anybody have a pinout for the jack? - Jami ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
On Wed, Sep 05, 2007 at 02:24:52AM +0300, Jami Pekkanen wrote: Hello, This isn't exactly maemo specific question, but I think this is the best forum anyway. I'm trying to solder together an adapter that splits the N800's 4-pole audio plug to two separate 3.5 mm females so that I can plug in separate input and output devices, eg electric guitar input and amplifier output (with maemo doing effects in between). So I took apart the headset that comes with the device and got the output part working fine, but I don't seem to get any signal to the input. In fact the device even doesn't switch the internal microphone off when I plug the modified system in. I'm assuming that there's two grounds (golden wires, another without coating), left output on a red wire, right output on green and input on white. The guesses were right for output, but as I said, the input doesn't get any signal at all. Is it possible that something special is required in the input connection? There at least seems to be some resistors in the headset's circuit, but I assumed they are just for the push-button. Also does anybody have a pinout for the jack? I know of a pinout for a very similar device: http://web.it.kth.se/~maguire/iPAQ-photos/iPAQ-audio-adapter.html E -- Erik Hovland mail: [EMAIL PROTECTED] web: http://hovland.org/ PGP/GPG public key available on request ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: N800 audio connector jack
On Sep 4, 2007, at 7:24 PM, Jami Pekkanen wrote: Is it possible that something special is required in the input connection? There at least seems to be some resistors in the headset's circuit, but I assumed they are just for the push-button. Also does anybody have a pinout for the jack? I've worked with some systems that sensed the input impedance. You may want to try putting a small resistor in there. I believe that one of the iPaqs even tried to work as mono out/ mono in or stereo out on three pins, depending on the impedance of the output. Perhaps measuring the impedance of the headset first, then putting resistors on to your device, and then taking them off one by one to see which was necessary would work? ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
