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WW Figure 7. Astable multivibrator circuit. Design an op amp-based astable multi

ID: 2081615 • Letter: W

Question

WW Figure 7. Astable multivibrator circuit. Design an op amp-based astable multivibrator to have an oscillation period of 13.50msl Your textbook discusses the astable multivibrator in detail, and you should consult it to understand the working of the circuit and how to do this design. In addition, you should base your design on the Schmidt Trigger of the previous section, maintaining the 20VJ hysteresis limits, and determine the proper R3C time delay circuit. (Hint: The Sedra and Smith textbook switches the names of RI and R2, and defines a variable called Bin terms of their values. You need to be very careful about your definitions and names if you use the formula in the textbook.)

Explanation / Answer

Time period of the astable multivibrator, T = 2 x 2.303 R3C ln ( (2R1 + R2) / R2 )

Assume R1 = R2

T = 2 x 2.303 R3C ln(3) = 5.06 R3C

T = 13.5ms

Let C = 4.7µF, then R3 = 567.65