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1 (33). The formula for the frequency of oscillation in an LC circuit is f= 1 √ 2π LC Here, we must therefore have 88.9 × 106 = 1 2π 1.4 × 10−12 L √ which gives L = 2.2 × 10−6 H (35). Again the need the same formula for the frequency. At the top of the band, 1 frequency of 1600kHz means 1 2π 2 × 10−6 C which yields C = 7.5 × 10−9 F and at the bottom 1.3 × 106 = .5 × 106 = √ 1 2π 2 × 10−6 C √ which yields C = 5 × 10−8 F (38). To change the voltage from 120 to 9, we must have a ratio of 9/120 for the turn number. Hence the secondary coil has N = 240 × 9/120 = 18. If the current in the secondary is supposed to be 400 mA, the power .4 x 9 = 3.6 watts.