One 40108 Schmitt inverter or one 4093 gate can be used as a half monostable to be triggered by the positive transition of the input. The amount of time the circuit is on is approximately 0.7 x R x C [R in ohm and C in farad]. It is the circuit shown here. The minimum value recommended for C is about 100 pF. For long monostable action, the TLC555 or the bipolar 555 is recommended.
Positive-Triggered Half Monostable
