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Need help learning how to analyze circuits

  1. Apr 5, 2013 #1
    On tests and homework in my electronics class, I have big problems trying to figure out how to analyze circuits to get information about various values such as Vout and Vin based on the specific circuit given in the problem. The questions we get are such that I need to draw a Vout vs Vin graph given a circuit, and that circuit could be anything. It could have diodes, capacitors, resistors, transistors, etc, and unless it's exactly like a circuit I've seen before, I can't figure out how to do it.
    Basically, I'm not knowledgeable enough about circuits and how the circuit elements behave in a circuit to be able to analyze the circuit to calculate the voltage or current values it will have at certain points.
    Does anyone know of any online resources that could teach me this sort of thing?
    The book I have isn't helping me.
  2. jcsd
  3. Apr 5, 2013 #2
    I would use LTSpice and punch in some simple circuits to start. After you get a feel for the simple ones start adding components slowly and guessing what might happen next. It's a wonderful tool to learn circuits. How many components are in the circuits you're expected to analyze?
  4. Apr 5, 2013 #3
    Thanks, I'll try that. I'm desperate, the semester is almost over and I don't want to fail.

    There's very few components. There's maybe 2 diodes and 2 resistors. But there will also be a voltage source, and then 2 other voltage sources in the middle, which completely throws me off. I don't know why they're there or what changes they make to any calculations of the Vout of the circuit.

    I've seen complicated circuits, and the stuff we're getting is nothing compared to that. This is one of those things that I'm just bad at understanding, so I need something that can teach me in a different way from what the teacher and the book is doing.

    Thanks again.
  5. Apr 6, 2013 #4


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    Have you spent much time with the professor and/or TAs in office hours? They are likely your best resource.
  6. Apr 6, 2013 #5
    I've spent some time with the professor, but it just didn't seem to help much. I don't learn very well from hearing someone speak. I learn best from books (because I can read and reread if I don't understand something. And then go back and reread again something I read before.), if they're good and teach the stuff that I'm going to be tested on. This book must just be teaching the stuff in a way that's not clicking for me. So I'm just trying to find alternate resources that might help me.
  7. Apr 6, 2013 #6


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    You won't learn how to analyze circuits by reading about it. You learn by doing lots of examples.

    Forget about "does it look like a circuit I already know about". Learn the basic techniques like Kirchhoff's voltage and current laws, and the other techniques that are in your textbook. Then practice using them.

    A simulation program might be useful as a learning aid, but remember you are trying to learn how to analyze circuits without any tools. That's not the same as learning how to use LTSpice.
  8. Apr 6, 2013 #7
    If you learn best from books, then read the reference book that you are using for the class. There are many books that teach basic electric circuits but not all of them are on the same point at the spectrum of excellence. Also, it's important to tell the title of the course. Is it a basic electric circuits course or an electronics circuits course? this is important so that alternative books can be recommended to you. For the mean time, check the two websites below. They provide an excellent, on the run textural tutorials on circuits and electronics. They combine theory and practical examples on a wide range of subjects.


  9. Apr 6, 2013 #8
    Good point. But one of my problems, I think, is I don't know how to figure out what the voltage or current is doing in the circuit. Using Kirchoff's laws is a good way to figure that out, but I don't know how to use that in circuits with diodes, transistors, capacitors, etc. When learning the Kirchoff's laws, the circuit examples in the book and given by the teacher only had resistors and power sources, so I don't know the extent to which I can use that law, or how to use it in more complicated circuits (if I can at all).
    Thank you. I'm actually currently reading my book (even though I don't feel like I'm learning much from it), and I'm reading allaboutcircuits.com as well, which I think is actually teaching me the conceptual stuff better than the book, but it's not explaining how to, for example, find Vout if a circuit has diodes, transistors, etc.

    The course I'm in is just called Electronics for Scientists. It's a required course for a bachelors in physics. It's all about basic circuits. Looks like it should be easy, and I'm sure it is to some, but this stuff just won't penetrate my brain.
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