Yeah!
My 'USB power upgrader' works!
It automatically switches on when input voltage from the CAS comes and switches off automatically when input voltage is off (when the calc is off through ctrl+on). A little green LED displays the state.
I can connect the output to a USB fan, and it's working...
BUT: when i connect to USB stick, the calc reboots instantly, even if it is running linux. (edit: oh, only with the very first version of linucx, with the newer the stick lights up) I think I connected the data wires wrong, so that data+ is connected to data- and vise versa. Not even one device is displayed by lsusb (watch -n1 lsusb).
So it restarts to prevent corruption of any devices...
Connecting to a hub doesn't do anything... not even hub LED is working... Only power consumption goes up to 550 mA.
I will try swapping the data wires...
If it is finished, I will post pictures.
If it is totally off, it doesn't need any power from the batteries (0 mA), when input comes in, it needs about 5 mA, and with my USB fan it needs 200 mA.
The power consumption at the batteries should be double as at the USB output port, because the L7805 has a efficiency of ~50% with 9 volts input.
1. EDIT: Just the power works, data transfer is not working, because of the two separated input/output power circuits, but the USB host needs to connect the data wires to ground to enumerate USB devices.
Now inventing a complete different circuit...
2. EDIT: My new circuit works! Even hubs are working with less power consumption than before
Just the off-switching part does not work correctly, there is always a output... Working on it.
The trick was - as I thought - the GND, which must be the same for input and output.