I have built up a circuit for charging my iPhone 3GS (bought in Germany) via hub dynamo while riding my bycicle.
The circuit works and creates a constant output of 5V at a speed > 10km/h (approx. 6mph).
I can charge all other devices without problem except my Iphone 3GS. -->The display shows the well known yellow triangle and: "Charging is not supported with this accessory."
So I applied the additional resistors at D+ and D- as described under the following for the MintyBoost "iCharging": http://www.ladyada.net/make/mintyboost/icharge.html
I expected a voltage of 2.0V (49.9K / (49.9K+ 75K) * 5.0V = 2.0V) at D+ -> Ground and D- -> Ground but there were only 1.85V
I think that has something to do with the input impedance of the iPhone so I increased the "49.9K" resistor to 62K which lead to a measured voltage of approximately 2.0V at D+ -> Ground and D- -> Ground.
But still the iPhone does not charge an and still shows following message on the display: "Charging is not supported with this accessory."
jsappo has posted that by renewing the dock connector the failure is gone. But he hasn't wrote about the MintyBoost circuit in particular.
Has any of you guy's had an iPhone 3GS which could not be charged with the MintyBoost (but with other devices) and after changing the dock connector charging progress worked with Minty Boost?
I just don't want to buy a new dock connector without seeing the chance that could fix the problem.
Thank you for your answers!