Help : resistance

Please use a fixed-type font next time. ASCII art comes out much better that way, and any reasonable newsgroup reader supports it.

I can't remember if there's a clever way to do this or not, but you can always use mesh or node equations. If you're not doing it for an assignment you can just put the network into SPICE, put a voltage across it, and measure the current.

Pls help how to calculate the total resistance at point x,y Thanks.

------ R1 ------ - ------ R3 ------ | | | | | | x ------- R5 ---------- y | | | | | | ------ R2 ------ - ------ R4 ------

This looks like a classic homework problem.

How do YOU think it is accomplished?

What have YOU tried , so far?

What does your textbook have to say about it?

Yes, this is sci.electronics.basics, but it shouldn't be a place to get homework answers with no effort on your part (though I am sure someone will provide you the answer just because they will feel orgasmic showing their superiority).

Richard the Grouch (at least for today) Enough fun. Now back to grading lab reports.

Pls help how to calculate the total resistance at point x,y Thanks.

------ R1 ------ - ------ R3 ------ | | | | | | x ------- R5 ---------- y | | | | | | ------ R2 ------ - ------ R4 ------

There are several ways it can be calculated. How did your instructor ask that it be done?

Try a delta-wye transformation.

Good advice.

No one has posted to my recent thread

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I can do it at least 4 different ways, but they all involve algebra. Here is a paper on one way:

John suggested Thevenin which is a good way. You may also look up loop analysis and Kirchhoff's laws. Its not a simple circuit and will involve considerable algebra. One way is to assign a voltage and solve the total current to calculate the resistance. If you are looking for a formula that addresses the five unknown resistances, you will have a large mess.

Tom

Possibly. You wouldn't be the first student who was incapable of finding or understanding information in a textbook. Some texts are better than others, as are some students.

"Just admit it, you know nuts about it."

Yep. You caught me. Feel any smarter now?

Richard

Looks like a dog's breakfast to me, due to=20 font/tab/space breakage. Is there a cleaned-up version of the circuit diagram that isn't ambiguous as to what's where?

Go have a look at this thread:

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This is a useful paper, but it doesn't answer the OP's question, which for this circuit would be "what is the resistance seen by the 25 volt source?".

Can you see a way to coax the answer to the OP's question out of a knowledge of the current through R5? I can't see one right away. I'll have to think about it.

I don't think it can be done without splitting the circuit and determining TWO Thevenin equivalents, as shown here (a reference you provided last year):