how can we modify the monostable multivibrator to obtain triangular wave generator

we can use monostable multivibrator.But generally its o/p is a square wave so to get a pulse type waveform,we may use differentiator after monostable multivibrator....

No, the output of monostable multivibrator does not oscillate. As it has only one stable output we do not get oscillations. We get a square wave as output.

A monostable multivibrator is a circuit which produces a single pulse of specified duration in response to each external trigger signal.

monostable multivibrator