Expt_06 - Lab-in-a-Box Experiment 6: Voltage and Current...

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Unformatted text preview: Lab-in-a-Box Experiment 6: Voltage and Current Dividers Name: __Josh Haynes_________ Pledge: _Josh Haynes_________ ID: __904321944__________ Date: __5/30/07 ___ ________ Procedure: Analysis: 1. Let x R 3 be the resistance between terminals 2 and 3 of the trim pot R 3 for the voltage divider circuit shown in Figure 1. Derive an expression for the voltage drop CD V across 2 R as a function of x. Note that terminal 1 of the trim pot is left floating in this circuit. Using Excel, MATLAB, or your choice of any other scientific graphic program, plot the resulting expression as x is varied from 0 to 1. 1, 3 Do not plot the data points, but only the lines joining them. Save this graph for use in steps 2 and 14. V_CD = 9 V * [(1 k)/(4 k + 10k*x)] 1 of 10 0.2 0.4 0.6 0.8 1 1.2 0.5 1 1.5 2 2.5 V_CD vs x V_CD (V) x V_CD V1 DC = 9 R1 3k R2 1k 3 1 2 R3 A D C B Figure 1: Voltage divider circuit. 2. Ground terminal 1 of the trim pot and repeat the calculations of step 1. Plot the results of this calculation on the graph created in step 1. Explain the difference(s), if any, between the two curves. What is the effect of grounding terminal 1 of the trim pot? 2 of 10 0.2 0.4 0.6 0.8 1 1.2 0.5 1 1.5 2 2.5 V_CD vs. x (Grounded) Column L x V_CD The two curves look similar but a trend arises in the second curve that causes V_CD's rate of dropping to slow, then to quicken. This is caused because grounding the terminal allows for extra current to escape through the trim pot. This allows the three resistors to function in parallel (two are in series), and not as we would expect with just a variable resistor. 3. Derive an expression for the current in the branch ABC and in the branch containing 2 R in the current divider circuit shown in Figure 2 as a function of x where x is defined in step 1. Note that terminal 1 of the trim pot is floating as in step 1. Plot the percentage of the total current generated by the source that flows through 2 R as a function of x . Save this graph for use in steps 4 and 24. I_ABC = [(3000 + 10000x)(1000)]/[4000 + 10000x] * [1000/(4000 + 10000x)] I_Source = [(3000 + 10000x)(1000)]/[4000 + 10000x] Percent of Source of I_ABC = I_ABC/I_Source 4. Ground terminal 1 of the trim pot and repeat the calculations of step 3. Plot the results of this calculation on the graph created in step 3. Explain the difference(s), if any, between the two curves....
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This lab report was uploaded on 04/10/2008 for the course ECE 2014 taught by Professor Lkpendleton during the Fall '07 term at Virginia Tech.

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Expt_06 - Lab-in-a-Box Experiment 6: Voltage and Current...

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