Circuit #J: Wien Robinson Active Notch Filter . The advantage of this filter is that the passband gain A can be adjusted without changing the value of Q, unlike the active twin-t filter. Figure 7 shows the circuit diagram for this Mter. The frequency-dependent portion is composed of the parallel and trim RC combinations between the two op-amps Figure 7 Wien Robinson action witch fiber . Equation 11 gives the transfer function for this circuit H (s) = with the additional variables defined as IT = . The filter parameters of the center frequency in. gain A, and quality factor O are ghen by Equations 14, 15, and 16: 1341 A=-17.1 A city of 5000 persons is to be served by a low-rate trickling filter with stone media and a polishing pond downstream from the final clarifier. Pertinent data are: wastewater flow = 95 gal/cap- day (360 6/cap-d), BODs after primary clarification = 135 mg/6, BODs after final clarification = 20mg/e, and filter bed depth = 5 to 6ft (1.83 to 2.43 m). Determine, using USCS units and Eq. (17.10): a. The theoretical filter diameter if the depth is assumed to be 5.5 ft. b. The design diameter if rotary distributors are available in 5-ft increments in diameter. c. The filter bed depth. 17.2 Repeat Problem 17.1 using SI units and Eq. (17.10) to determine the filter diameter if the depth is 1.67m.4. Suppose a species has a constant birth rate but the death rate is pro- portional to the population. For clarity by birth rate and death rate we mean births/deaths per unit of population. (a) (5 points) Write down the differential equation modeling this system. Your answer should include two constants B, D relating to the birth and death rate respectively. (b) (5 points) Suppose that B - 4.5, D - 1. Find the critical points of the system and analyze their stability