Hallo!
Probier mit C, der Flanken verbessert.
Code:
                      VCC
                       +
              C        |
                      / \
              ||     ( M )
           +--||---+  \ /
           |  ||   |   |
           |  ___  | |/
     PWM >-+-|___|-+-| T
                     |>
              Rb       |
                      ===
                      GND

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