I found a motor including a mounted wheel for accelerating the ball - it consumes 500mA at 3V. A second motor is needed for applying the spin. I need a lot of servos for different tasks, some are weak (consuming 150mA at 5V) others strong (consuming 1A at 5V). The RaspberryPi itself will need approximately 1A at 5V. The last part is a stepper which will drive the push mechanism to move the balls to the accelerating wheel. That stepper will consume about 1A at 12V. So I will need a lot of current at 3V (1A), at 5V (~5A) and at 12V (1A).
But wait a minute: aren't those voltages provided by a regular ATX power supply? Yes they are. Except 3V but 3.3V will work as well.
There are some projects out there providing an ATX power supply for driving a RaspberryPi. But wouldn't it be boring simply ordering another part? It is much more interesting to build a circuit on my own. And this is what I did:
On GitHub you can find all information how to build it on your own:
https://github.com/RasPelikan/raspberrypi-atx
