Recent content by phantom_photon

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    Synchronous machine confusion

    Please find attached a diagram of a two-pole, three-phase synchronous machine. In this diagram a', b' and c' are connected to neutral while a, b and c actually represent independent sets of coils distributed around the stator interior. They are connected in series so that the EMF induced in each...
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    Synchronous machine confusion

    Hello, I'm a little confused about synchronous machines. Specifically, I don't understand how the armature coils are wound. In discussing how the windings are configured in a three-phase synchronous machine, my textbook provides several diagrams which suggest that the windings of a coil go...
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    Why is Digital Butterworth lowpass?

    Well, Rizzoni's book "Principles and Applications of Electrical Engineering" comes to mind! It is written for the non-electrical engineer and covers a broad range of topics with lots of relevant examples. I don't think it has anything on digital filters though...
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    Choosing a post differential equations math course.

    A knowledge of numerical methods is always a good thing for engineers to have. It's probably not as valuable in EE as in Mech. Eng. or something like that, but it's still worth considering. You would learn about numerical techniques for solving large linear systems, computing eigenvalues...
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    Choosing a post differential equations math course.

    Then you should ask your school for your money back! :smile: Just kidding, I'm sure you'll find more uses for linear algebra soon enough. As Maxwell has mentioned it depends on your specialisation. For example, PDEs might be worthwhile if you're into radio engineering, coding/information...
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    An Op-Amp question

    This is a bit more complicated than your first example but can be solved in much the same way. It just involves a little more algebra. In your analysis you will be assuming an ideal op amp, i.e. infinite open loop gain and input impedance and zero output impedance. You should end up with a gain...
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    An Op-Amp question

    Use the formula for voltage division over two resistors in series: V1 = V*R1/(R1 + R2) So you must insure that the load impedance is large compared to the output impedance, for maximal voltage amplification.
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    An Op-Amp question

    -R2/R1 is the unloaded gain. When loading is taken into account the gain becomes -(R2/R1)*RL/(RL + Ro) where Ro is the output impedance. With a typical op amp, Ro is low by design and is commonly neglected. As long as RL is above 100 ohms or so, you may neglect loading (in my experience).
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    Phasor conversion help

    Where's the second one? Just put the first factor into polar form and multiply, like so: (8-j3)*5*exp(-jx) = Sqrt(73)*exp(-j*0.3588)*5*exp(-jx) = 5*Sqrt(73)*exp(-j*(x+0.3588)) which converts to 42.72*Cos(wt - x - 0.3588), assuming, of course, that the phasors are of the same frequency, w.
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    Impedance equivs and complex numbers.

    What works best for me is to rationalise the denominators (by multiplying numerator and denominator by the complex conjugate of the denominator) then simply adding real and imaginary parts. After rationalising, the denominator will be the square of the modulus while the numerator will be the...
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    Input Matching

    I guess the simplest explanation would be that if the domain of the response is extended to include t = 0 (or 0-) it will have an additional component: the system's response to the impulse while the impulse is being applied, which is of course a scalar multiple of the Dirac delta function...
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    Analog vs digital

    That's what I was thinking, but there's still the issue of sample resolution... the sampling theorem doesn't tell us anything about that... or does it? Could someone with DSP expertise settle this matter for us, please?
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    Analog vs digital

    Sorry, I must have misunderstood the sampling theorem. I thought that it was possible to recreate a 20KHz signal (and others of lower frequency) perfectly by means of a weighted sum of normalised sinc ( = sin(pi*x)/(pi*x)) functions but I think I got the wrong idea. You might be thinking of...
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    Analog vs digital

    Audiophiles seem to have a preference for analogue media like LPs, saying they have a "warmer" sound. I guess it's a pretty subjective matter really. But some would argue that no recording media can ever be truly analogue since LPs, for example, are limited in sample rate/resolution by the...
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