# Thevenin-Norton conversion

Discussion in 'Electronics Homework Help' started by yorge26, Dec 13, 2017.

1. ### yorge26

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Dec 13, 2017
How would I start on this type of circuit?

2. ### Ratch

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Mar 10, 2013
1. Use loop, node, or branch analysis to find the voltages and currents.

2. Determine the voltage across the open terminals a-b. That will be the Thevenin voltage. Then short terminals a-b and determine the current existing in the short. That will be the Norton current. Divide the voltage by the current to get the Thevenin resistance.

3. Point out that the load resistance is not used in determining Thevenin-Norton voltages, currents, or resistance.

Ratch

3. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,418
2,788
Jan 21, 2010
Well, I presume you know that this equivalency allows you to interchange a current source having a parallel resistor with a voltage source having a series resistor.

All you need to find are examples of one of these that could benefit from being converted to the other, and do the conversion.

I find the easiest way is to calculate the short circuit current and the open circuit voltage. These two figures allow you to easily calculate the parameters of the voltage or current source and the accompanying resistor.

4. ### The Electrician

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Jul 6, 2012
I think that the problem wants the student to enter the schematic into Pspice and then use Pspice to do the DC analysis, finding all the currents and voltages.

Then do some simplification with source conversions.

For part 3 I think they want the student to use several different load resistors and use Pspice to determine the voltage across the various load resistors. Then working backward, knowing the voltage across a particular load resistor, the student can determine what the Thevenin equivalent of the given circuit must be. That Thevenin equivalent should be the same no matter what the load, and the problem wants the student to take that as proof that the Thevenin equivalent is the same no matter what the load resistor.

I'm not sure that is a rigorous proof, but I didn't write the problem.