Various Waveforms of the Monostable Multivibrator:

Now since, V₂ < 1/3 V_cc, pin 7 opens up and capacitor C₀ charges exponentially towards + V_cc and continues till V_co >(2/3) V_cc at which time, timer output goes LOW. Now, pin 7 is shorted to ground and V_co becomes zero. Therefore, the circuit comes back to its permanent stable state and shall remain so unless another trigger pulse is applied to begin the operation all over again.

Figure: Various Waveforms of the Monostable Multivibrator

The time period during which waveform remains HIGH can be determined as follows.

The general equation for the capacitor voltage may be written as V_co = A + B e ^{-t/R f C0}   in

which constants A and B may be found by applying the conditions : at t = 0 , V_co = 0 and at t = ∞ , V_co = + V_cc which provides the values of A and B as A = V_cc and B = - V_cc, so that

we have,

V_co  = V_cc  (1 - e ^{-t/R f C0}  )

Now for t = T, Vco =  +(2/3 )V_cc, therefore, one finds,

                                                            T = R_F C₀  ln 3

The required trigger pulse may be obtained by the modification illustrated in Figure which is self-explanatory.

Figure: Modified Monostable Multivibrator