Multiple Ipod Charger

My task: Provide a Charger that allows to charge multiple IPods at the same time.

Resolution:
1. Use a switching Power Supply 5V/10A to charge 20 IPods (500mA each). The voltage must not go outside the below limits:

4.9 <= V <= 5.4
2. Use the below diagram to provide a voltage divisor for the D+ and D- pins of the USB (in my case type A) connector

(+) --- 75K --- (D-/D+) --- 51K --- (-)

The USB Ipod connector uses 4 cables plus ground shield. They must be connected to the connector as indicated below.

1 (+) Red
2 (D-) Green
3 (D+) White
4 (-) Black and Ground Shield