555 - Monostable multi vibrator

Monostable Multivibrators or One-Shot Multivibrator is used to generate a single output pulse of a specified width. This multivibrator need a trigger (external signal) to enter into the astable state and get back to the stable state after some time period. The time period will be set by the charging and discharging of the capacitor, the monostable multivibrator is mainly used as timer.