Lab_6 - EE 101A / Winter 2010 Lab #6 (For weeks of 2/22 and...

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EE 101A / Winter 2010 Lab #6 (For weeks of 2/22 and 3/1) Page 1 of 9 1. Motivation: Making our converter a “better” voltage source We’ve spent several weeks building an AC/DC voltage converter to use as a power supply, which is really a voltage source. For the first few labs, we focused on converting what comes out of the wall into a constant voltage of around 15 V. In Lab 5, we added a neat feature that allowed variable output voltage. However, we also determined that the output resistance was too large for it to be a high quality power supply. Now we’d like to build an output stage that will allow our circuit to connect to various loads with minimal degradation in performance. We explored the concept of loads in Lab 4. We revisit this concept because anything to which we connect our converter can be thought of as a load. A “good” voltage source can deliver its advertised voltage to as wide a range of loads as possible. One way to measure the “quality” of a voltage source is called the source resistance R S . This is the effective resistance seen looking into the output of the source. Question 1: Let’s say we have a 10 V source with R S = 1 k as shown below. Calculate the voltage that appears across each of the following loads. Question 2: An ideal voltage source is capable of driving any load. What is its R S ?

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