Experiment 3 Power Supply Design

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The primary design problem was to build a power supply in accordance with the requirements for Design C. That is, a DC output voltage, VO = VL of +15 V ± 0.5 v; Nominal DC voltage at regulator inpu... t, Vc of +24 V; Ripple voltage at regulator input, Vr of 15% of VC with rated load resistance attached; RL to dissipate approximately 1 watt; AC input voltage and frequency of 120 V RMS, ± 5%, 60 Hz. We had to design the full wave rectifier with filter capacitor and then the voltage regulator. In order to pick the proper components we de-rated the maximum voltages and currents by at least half for circuit reliability. This is a schematic of the power transformer borrowed from the stock room. We discovered the following characteristics: VOC A-B = VOC B-C = 10.5 V RMS = 14.8 V peak VOC A-C = 20.9 V RMS = 28.8 V peak In order for Rtest to dissipate 1 W, Rtest = VL 2 / P, Rtest = 390 Ω VL RMS = 20.5 V To find RW: VA-C RMS – VL RMS = 0.4 V drop across RTH, or 2*RW I = 20.5 / Rtest = 52.5 mA 2*RW = 0.4V / I RW = 3.8 Ω Rectifier: Since we needed a VC of +24 V, we needed to use the full-wave bridge rectifier, as the center tapped can only produce a max of 14.8 V at VC . As a result, we are only using pins A and C of the transformer to generate the + 24V necessary at Vc [Show More]

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