Question 15.8: Objective: Design a Schmitt trigger oscillator for a specifie...

Using Equation (15.88), we can write

f = \frac{1}{T} = \frac{1}{2.2 R_{X} C_{X}}       (15.88)
R_{X} C_{X} = \frac{1}{2.2 f_{o}} = \frac{1}{2.2(103)} =  4.55 × 10^{−4}

If C_{X} = 0.1  µF, then R_{X} = 4.55  k\Omega.

Trade-offs: Using standard-valued elements with values of C_{X} = 0.082  µF and R_{X} = 5.6  k\Omega produces an oscillation frequency of 990 Hz, within 1% of the specified value. If lement tolerance values are taken into account, a potentiometer may have to be sed to produce the 1000 Hz oscillation frequency.
Comment: A larger frequency of oscillation can easily be obtained by using smaller capacitor value.