The MDA mobile 'phone (also marketed as the I-Mate Jam, XDA Mini, SPV M500 (Orange) ) charges using it's mini USB connector.
I decided to create a solar charger for it allowing me to take it on my travels (to sunny places) without having to worry about the charger, finding a plug socket and converter. I had a spare solar panel that outputs around 8V and a few spare components.
According to the diagram from http://pinouts.ru/data/USB_pinout.shtml , pins 1 is +5V and pin 4 is ground. All I had to do was to connect a 5V source to these pins. I acquired a miniature USB connecter from a digital camera cable and removed the normal size USB connector. The leads are coloured, and the 5V should go to the red lead and ground to the black lead, the lead shielding should also be connected to ground. However, the 'phone refused to charge and, after much head scratching and taking the original charger apart, I was still none the wiser.
Still none the wiser
I eventually prised apart the connector of the lead that goes into the 'phone and found 5 wires, not 4. This wire only had a reference in the diagram but no number and no cable going to it. I soldered this wire to the wire next to it (pin 4).
Carefully putting this back together and plugging it to the 'phone, hey presto! The orange charge light came on and the 'phone was charging.
This is based around a 7805 voltage regulator, the 'phone must only get 5V. The regulator takes the large voltage from the panel and ensures it never goes above 5V. These are available in the UK from Maplin, DigiKey, Farnell and RS components. The circuit is:
How to hand charge your iPod: http://geektechnique.org/projectlab/236
Disclaimer: Connecting items to your mobile 'phone can invalidate your warranty and break it. You need a basic grounding in electronics before this project can be attempted. I do not take responsibility for your actions. Please take care.
Sam Wane January 2006