WEBVTT 00:00:00.000 --> 00:00:05.525 Now that we know how to calculate the Thebonon equivalent circuit, it's very easy to get the Norton 00:00:05.525 --> 00:00:08.936 from source transformation. The Norton equivalent current is going 00:00:08.936 --> 00:00:13.911 to be V Thevenin divided by R Thebonin, and the parallel resistor here will be 00:00:13.911 --> 00:00:20.440 equal to the series resistor in Febonin. Now let's talk about power transfer. 00:00:20.440 --> 00:00:24.264 When we have our active circuit, which we can model with a Febonin 00:00:24.264 --> 00:00:27.900 equivalent circuit, and our passive circuit, which was modeled just as a load, 00:00:27.900 --> 00:00:32.500 we might very often want to be able to maximize the power that gets to the load. 00:00:32.500 --> 00:00:35.531 Imagine what would happen if we increase this resistance. 00:00:35.531 --> 00:00:39.140 We can see that by increasing the resistance because we've got a voltage divider here, 00:00:39.140 --> 00:00:43.095 we get the larger possible voltage, but we get a much smaller current 00:00:43.095 --> 00:00:47.700 because from Ohm's law that says we have a higher resistance. What if I made the load very small? 00:00:47.700 --> 00:00:52.133 In that case I have a large current but a small voltage. So in fact, 00:00:52.133 --> 00:00:57.190 where's the maximum power transfer? If you calculate the current and you calculate the voltage, 00:00:57.190 --> 00:01:00.950 you'll come up with this equation right here. And if we plot that, 00:01:00.950 --> 00:01:05.350 we'll see that the maximum value happens when the load is equal to the source. 00:01:05.350 --> 00:01:10.698 So our maximum power transfer happens when Rs and RL are matched. You often say matched, 00:01:10.698 --> 00:01:16.470 and this is the maximum power that can be delivered to that load. 00:01:16.470 --> 00:01:20.920 Now here's our electrical engineering circuit analysis toolbox with the addition 00:01:20.920 --> 00:01:25.082 of Thevenin and Norton included. Now, Febin and Norton are very important because 00:01:25.082 --> 00:01:28.914 they allow us to simplify our circuit. They're somewhat like the resistors and 00:01:28.914 --> 00:01:35.658 series and parallel law that allows us to simplify or the superposition. So let's say that this is 00:01:35.658 --> 00:01:41.250 a simplification method, this is a simplification method, and this is a simplification method. 00:01:41.250 --> 00:01:46.080 The other methods can all be used in this Norton and Febin equivalent circuit. 00:01:46.080 --> 00:01:50.040 In fact, you saw us use the node voltage and this equation right here. 00:01:50.040 --> 00:01:54.040 Ohm's law can also be used voltage dividers and current dividers, 00:01:54.040 --> 00:02:00.400 all for doing the analysis that gives us the feminine and Norton equivalent circuits. 00:02:00.400 --> 00:02:05.345 So what did we do today? We talked about how to analyze systems of circuits that might be 00:02:05.345 --> 00:02:08.640 more complicated by breaking them down into simple blocks using the 00:02:08.640 --> 00:02:12.572 concept of input and output resistance. We know that if the output resistance 00:02:12.572 --> 00:02:16.765 is much smaller than the input resistance of the next block that we can 00:02:16.765 --> 00:02:21.100 analyze these individually and if not, we can expect to see voltage loading. 00:02:21.100 --> 00:02:24.152 We analyzed how to calculate feminine 00:02:24.152 --> 00:02:29.780 equivalent circuits by open circuiting 00:02:29.780 --> 00:02:34.660 the points A to B and measuring or simulating or calculating B feminine. 00:02:34.660 --> 00:02:39.820 And then we talked about three different methods of being able to measure our Thevenin. 00:02:39.820 --> 00:02:44.700 We know that we could convert this to a Norton equivalent circuit using source transformation. 00:02:44.700 --> 00:02:49.580 And then we talked about maximum power transfer, which is where the block that has this 00:02:49.580 --> 00:02:53.491 input resistance rather the output resistance is connected to the load 00:02:53.491 --> 00:02:57.948 and these two have to be matched or equal for maximum power transfer. Finally, 00:02:57.948 --> 00:03:02.201 we talked about the updated EC analysis toolbox where we now know that we 00:03:02.201 --> 00:03:05.780 can use Thevenin and Norton as one of our simplification tools and we 00:03:05.780 --> 00:03:10.500 can apply any of the other circuit analysis tools to do our calculation. 00:03:10.500 --> 00:03:17.068 So thanks very much for joining me for the discussion of Thevenin and Norton equivalent circuits.