8.4 COMMUTATING CONDENSERS

In the initial stable state Q2 is ON and in saturation, Q1 is OFF. Once a trigger is applied [see Fig. 8.3] to change the state of the devices in the monostable multivibrator, because of the stray capacitances of the devices they may not go into the next state immediately. This is a problem which needs to be overcome.

Now, let a negative pulse be applied at the base Q2 to drive it into the OFF state and consequently Q1 into the ON state. Prior to the application of this trigger the voltage at the second collector was VCE(sat). On the application of a trigger at t = 0, as Q2 goes into the OFF state, the voltage at its collector rises from VCE(sat) to VCC. Let the change in voltage at the second collect be vi, a step ...

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