3. When the threshold voltage reaches 2/3 Vcc, the flip-flop resets, connecting discharge to the ground and setting output to low. It is now back in the initial state, and awaits another trigger pulse.
By selecting the resistor and capacitor, the length of the output pulse can be controlled. If the trigger receives a signal while the output is still high, there is no effect. This circuit can be used for debouncing.
Figure 4.