If anybody is interested here is my power supply project
The basic circuit is similar to that published in MagPi October 2012. I added a PIC microcontroller to the circuit to help in powering down or powering up of the Raspberry Pi. The microcontroller has its own 3.0 V regulator so it is operational when the Raspberry Pi is powered down. The current consumption for the PIC with the power supply in off state is less than 1 mA.
The microcontroller allows reading of the battery voltage. At the Raspberry Pi a daemon called 'pipicpowerd' is reading the battery voltage every five minutes. The result is written to the log file /var/log/pipicpowerd.log. If the battery voltage is too low the PIC is programmed to power down after about 100 seconds. If the file '/var/lib/pipicpowerd/wakeup' exists it is read (for example "8:00") and is used to calculate the power supply wake up time. This value is then programmed to the PIC to wake up the system at later time. After the PIC has been programmed the 'shutdown -h now' command is executed at the Raspberry Pi.
The shut down and power down can also be initiated by long press on the red button. The red LED is turned on at the power supply. If the button is pressed again shut down and power down is initiated.
There is a PDF-file that can be printed with a laser printer (or copied with a copy machine) to produce a printed circuit board with the toner transfer method. The polyfuse on the schematics is not yet placed on the PCB.