Für digitale Signale am einfachsten so:
Code:

                                   VCC
                                    +
                                    |
                                   .-.
                                   | |R2
                                   | |
                                   '-'
                                    |
                       R1      OK   +--->
                       ___  .-------|.
                  >---|___|--+      ||
                            ||    |/ |
     von Sensoren           |V -> |  |   zum µC
                            |-    |> |
                            ||      ||
                  >-+--------+      ||
                    |       '-------|'
                   ===              +--->
                   GND              |
                                   ===
                                   GND

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