Ich habe es inzwischen skizziert ...

MfG
Code:
       Richtig -> GND1 = GND2 = 0

       +-------+       +----+
       |       |       |    |
       |    .-----. .-----. |
    A1 -    |VCC1 | |VCC2 | - A2
      ---   |     | |     |---
       |    |GND1 | |GND2 | |
       |    '-----' '-----' |
       |       |       |    |
       +-------+---+---+----+
                   |
                  ===
                  GND

       Falsch -> GND2 = GND + I * RL -> VCC2 gegen GND hängt von I ab

       +-------+       +----+
       |       |       |    |
       |    .-----. .-----. |
    A1 -    |VCC1 | |VCC2 | - A2
      ---   |     | |     |---
       |    |GND1 | |GND2 | |
       | RL '-----' '-----' |
       |  ___  |       |    |
       +-|___|-+-------+----+
       | <---
      ===  I
      GND

(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)