(3)Calculate the parameters and compare them to measured values Parameters Equations Calculated value Measured value Charge time(s) 4≈0.693R+R)C Discharge time(s) 5≈0.693R·C Period(s) T=4+h Frequency(Hz) f=1T Duty Ratio D(R+R)/(R+2R) (4)Replace R =100k with R.=330k2.Record t,,T,f,D 11.4.2 Experiment 2:.Schmitt Trigger Sometimes an input signal to a digital circuit doesn't directly fit the description of a digital signal. For various reasons it may have slow rise and/or fall times,or may have acquired some noise that could be sensed by further circuitry.It may even be an analog signal whose frequency we want to measure.All of these conditions,and many others,require a specialized circuit that will "clean up" a signal and force it to true digital shape. The required circuit is called a Schmitt Trigger.It has two possible states just like other multivibrators.However,the trigger for this circuit to change states is the input voltage level, rather than a digital pulse.That is,the output state depends on the input level,and will change only as the input crosses a pre-defined threshold.(3) Calculate the parameters and compare them to measured values Parameters Equations Calculated value Measured value Charge time (s) 1 0.693( ) a b t R RC   Discharge time (s) 2 0.693 b t RC   Period (s) Ttt  1 2 Frequency(Hz) f 1 T Duty Ratio =( ) / ( 2 ) DR R R R ab a b   (4) Replace 100 Ra  k with 330 Ra  k.Record 1 2 tt TfD ,,,, 11.4.2 Experiment 2:．Schmitt Trigger Sometimes an input signal to a digital circuit doesn't directly fit the description of a digital signal. For various reasons it may have slow rise and/or fall times, or may have acquired some noise that could be sensed by further circuitry. It may even be an analog signal whose frequency we want to measure. All of these conditions, and many others, require a specialized circuit that will "clean up" a signal and force it to true digital shape. The required circuit is called a Schmitt Trigger. It has two possible states just like other multivibrators. However, the trigger for this circuit to change states is the input voltage level, rather than a digital pulse. That is, the output state depends on the input level, and will change only as the input crosses a pre-defined threshold