What is it about it you want/need to know?
There's a push button, a debounce circuit (IC1), a decade counter (IC2), and 10 speed trimmers, but in the end it's IC3 (555) that performs some kind of PWM.
Anyway, it's a hideously clumsy & difficult circuit to set up & operate. Who's going to push a button 9 times (driving a car) to step the wiper speed down one notch?
