[AnalogArsonist]

I finally got a new multimeter (thank you baby Jesus) and ripped apart my dock, destroying it in the process. However, I'm creating the schematic as I type this. Pin 11 goes into the transistor Q1 but right now I can't tell if it's the base, emitter, or collector (it could be a MOSFET too, shouldn't matter). I can't tell what the part number is for the transistor but it should be obvious when I'm done testing all the pins. I need a magnifying glass..my eyes hurt now

Anyone want to make speculations on how this circuit works together? There is a monostable multivibrator and a transistor with a handful of caps and resistors. Pin21 and Pin11 both go to the transistor eventually.

 

[AnalogArsonist]

Someone try this: short pin 7 to pin 2 (audio grounds), float pin 21, and ground pin 11. If that doesn't work try putting a 357k resistor from pin 21 to GND. Audio channels need to be hooked up too, obviously. As far as I can tell, pin 11 and pin 21 are only connected through transistor Q1. If someone has a magnifying glass they should try to see if there is a part number on Q1 because I sure as hell can't see with the bare eyes.

 

[Juaquin]

Thanks for checking AnalogArsonist, can't wait to hear the final diagnosis.

I made a LOD with the 1K resistor method and I can confirm that it outputs audio (of course, the airplane mode message does still pop up).

I've run into a bit of a problem using the LOD with my Fiio E5 - the LOD output is of high enough amplitude that the lowest setting on the E5 is a little too quite, the next is on the high end of my listening volume, and the next is way too loud - and that's only going part way up the scale. Of course my CmoyBB works fine with the LOD, but the E5 doesn't have enough resolution in volume adjustment, so I've been using the headphone jack to supply the E5.

 

[AnalogArsonist]

Juaquin, I think the lineout of these devices is meant to be controlled by an amp/receiver/whatever. On the IPhone dock's lineout, the volume cannot be controlled by the phone. This is because of the expectation that an amp will be hooked up. You could always just put a volume control of your own on there (sliding variable resistor like some headphones have?).

Also, getting lineout from the iphone is easy it's just that I think everyone wants to do it without the airplane mode message.

 

[Juaquin]

Yeah, I know the dock output is a set amplitude and there's no control on it. I was just pointing out that it's rather high, which means each notch of volume on my Fiio E5 amp makes a large jump - so large that its hard to get a comfortable volume. I don't have that problem on my Cmoy, as it has a potentiometer, allowing smaller jumps and thus more control over the volume.

Anyways, thanks for ripping apart the dock, can't wait to see how to disable the message.

 

[fakcior]

Quote:

Originally Posted by stevenkelby /img/forum/go_quote.gif Hi Thuan Tran, Use 2, 3 and 4 for the signal and ground, just like a normal dock, then use a tiny short piece of wire soldered from pin 11 to pin 15. Pins 1,2,15,16,29 and 30 are all "ground", they are all connected to the same trace inside the ipod/iphone, so you can use any of them for ground. You can use the same pin (1,2,15,16,29 or 30) for audio ground and to connect to pin 11, or different pins, it doesn't matter as they are all connected anyway. You must connect one of them to pin 11 though for an iphone/touch LOD to work, it's just easiest to use pin 15 as it's closest to pin 11. You don't need to use any resistors. Hope that makes it clear!

Is this work with iPhone 2G or 3G or both?

Regards

 

[Juaquin]

iPhone 2G = iPhone 3G for purposes of the dock and headphone connector, so both.

I've been thinking about doing a split IC cable, with a male dock going into the iPhone and a mini connector AND female dock on the other end. That way you can charge (using a regular charger) and listen to music at the same time. Might be an interesting project. Are there an caveats there, such as needing a correct resistor combination for charging or anything?

 

[AnalogArsonist]

Happy new year everyone. I believe I have found the proper resistance that the dock appears as to the IPhone. 66k. I wrote up why that is on my blog and if anyone cares to read it they can go here. Currently, I have line-out audio and the message no longer comes up. I'd like it if others tried this as well so I know it's not just me going crazy.

As for the charging circuit, I believe that has been covered before but I have a charging/line-out circuit that runs off a 9v battery on my blog as well. It has nothing to do with resistance but with a proper voltage on USB D+ and D- pins.

 

[maxmath]

@Analog: Instead of a linear regulator circuit, you can use a boost circuit as discussed here => Minty Boost! - USB charger for your gadgets

Disclaimer: I have nothing to do with the attached link. Just something that I might do in the future for my iPhone.

 

[ruZZ.il]

Quote:

Originally Posted by Juaquin /img/forum/go_quote.gif ..each notch of volume on my Fiio E5 amp makes a large jump - so large that its hard to get a comfortable volume...

This is a result of a (too) high gain setting on the amp. The gain determines how much the signal is amplified, and the travel that you get from its volume control accordingly (I'm sure you know this already). If you were to use higher impedance headphones, you'd get smaller volume increments, with a lower "highest" volume though. A Higher gain also amplifies the noise a bit more, but the higher the impedance, the more "voltage driven" (opposed to current driven) the headphones are, and the noise level is less effective. For these reasons, low gain is selected for low impedance / sensitive cans, so that the noise level is lower, and you get to use more range of the volume within your comfort zone. Higher gain is used with higher impedance cans accordingly. I'm not familiar with your amp, but if it has a gain switch, use it, otherwise, you may be able to mod it. it's usually just a matter of switching out a resistor or 2 per channel..

 

[fakcior]

@AnalogArsonist
Can you draw simple scheme of only line-out pins with 66k resistor, because I don't understand that complicated scheme on your blog.
Regards!

 

[Juaquin]

Quote:

Originally Posted by ruZZ.il /img/forum/go_quote.gif I'm not familiar with your amp, but if it has a gain switch, use it, otherwise, you may be able to mod it. it's usually just a matter of switching out a resistor or 2 per channel..

Unfortunately the Fiio is a tiny little integrated amp, and ripping it apart to replace Rf and/or Rs to change the ratio (and thus gain) would probably destroy the poor thing. Just wanted to point it out to anyone who was considering using a LOD with an E5.

 

[Juaquin]

Quote:

Originally Posted by AnalogArsonist /img/forum/go_quote.gif Happy new year everyone. I believe I have found the proper resistance that the dock appears as to the IPhone. 66k. I wrote up why that is on my blog and if anyone cares to read it they can go here. Currently, I have line-out audio and the message no longer comes up. I'd like it if others tried this as well so I know it's not just me going crazy.

Sweet, I'll give it a shot soon when I make my next LOD.

 

[AnalogArsonist]

Quote:

Originally Posted by fakcior /img/forum/go_quote.gif @AnalogArsonist Can you draw simple scheme of only line-out pins with 66k resistor, because I don't understand that complicated scheme on your blog. Regards!

The last post I did was the simple schematic.

1. Tie Pin 21 to GND with a 66k resistor
2. Tie Pin 11 to GND
3. Pins 3 and 4 go to their respective left and right speaker "+" terminal
4. Pin 2 goes to the "-" terminal of both speakers

I think that's it. Note that there are many GNDs and I think they are all connected except for pins 2 and 7.

 

[AnalogArsonist]

Quote:

Originally Posted by maxmath /img/forum/go_quote.gif @Analog: Instead of a linear regulator circuit, you can use a boost circuit as discussed here => Minty Boost! - USB charger for your gadgets Disclaimer: I have nothing to do with the attached link. Just something that I might do in the future for my iPhone.

Thanks Maxmath. I actually came across that when I was first trying to build a charger for my iphone. I chose to use a 9V battery just for testing purposes and when I build my own custom dock it will be plugged into the wall and be a POL switching regulator. For a portable charger I think the Minty Boost is great!