<div><span class="gmail_quote">2008/2/22, Andy Green <<a href="mailto:andy@openmoko.com">andy@openmoko.com</a>>:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Well it is interesting but the charger thing is a done deal for us<br> already and it is okay as far as it goes. It would have been nicer to<br> use this standard method, but if as Harald says if it turned up too late<br>
to use it, well its okay.</blockquote><div><br>I understand. The specification is less than a year old, and it takes time until it is implemented in widely used chipsets.<br><br>However, I hope you can consider adding a user-space interface for specifying the charging current. Then I could violate the USB specification and build a device that would charge the OpenMoko while it is in USB host mode. The device would provide a USB HID interface to some sensors, such as odometer (about 85 mm steps from the dynamo hub), cadence, and heart rate. Then the OpenMoko would record all this information during the bicycle trip.<br>
</div><br>Failing that, I think I can afford to wait a couple of more years for the next
generation. By then I reckon there will be greater selection of GPL navigation software as well.<br><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
> to load. The nominal output current of the SON28 that I have in my bike<br> > <<a href="http://www.nabendynamo.de">http://www.nabendynamo.de</a>> is 580 mA. If the current limit in the<br> <br> Its a lot of power! But this is just a matter of regulation before<br>
giving it to the device.<br> </blockquote></div><br>Right. The overvoltage protection consists of two 5-watt zener diodes before the MOSFET rectifier bridge, and a low-dropout 5-volt regulator after the rectification. I hope it will be sufficient, but I'll have to test it to be sure. This protection will be needed when there is too little or no load when the circuit is connected to the dynamo. For instance, old (3.5mm) Nokia phones tend to interrupt the charging current at about 2 Hz rate. Without any load after AC/DC rectification (testing with a salvaged wall-wart), I measured up to 96 volts from the output capacitor. :-)<br>
<br>Marko