Recent content by hogshead

  1. H

    I What causes alternator waveform shape?

    Yes, I can see that they are not noise. What I'm trying to understand is why the distortion is at harmonic intervals and not just noise. I also want to know the technical name for this so that I can do more research (Google and that kind of thing). It seems to me that since the distortion...
  2. H

    I What causes alternator waveform shape?

    So, if I am understanding this correctly, the quick rises and falls and sharp corners and such are distorting the wave from being a sine wave? Why are the spikes in the frequency analysis at multiples of the fundamental frequency and not just noise?
  3. H

    I What causes alternator waveform shape?

    Thanks for the help. The alternator has cast-iron pole pieces, so I could see how hysteresis could be a factor. Also I could see how geometric considerations could cause the flux to not be distributed evenly. Why is there a seemingly infinite series of harmonics (at least I assume in theory...
  4. H

    I What causes alternator waveform shape?

    I have a permanent magnet alternator. It does not produce a sine wave output, but rather a sort of distorted triangle wave. I did a frequency analysis on it and it showed a series of harmonics. The strongest was the third, with each odd harmonic getting progressively less powerful. It also...
  5. H

    What is the name for a pulse of current?

    A steady state electrical current is called DC. A periodic rising and falling current is called AC. What is a single-polarity pulse of rising current ( a single rectified hump of a sine wave e.g.) called? AC? DC? or something else?
  6. H

    3rd order harmonic distortion with PM alternator

    I have fashioned permanent magnet alternators with air cores and with iron cores. The air core units generate a sine wave (or something close to it), but the iron core units have third order harmonic distortion, (see waveform). Why is this?
  7. H

    Calculating q factor of an inductor

    Ok, I was assuming that the q factor of the primary and secondary somehow corresponded. What I really want to know is the q factor of the primary. Later, I'd like to figure out how to calculate iron losses from hysteresis and eddy currents. These coils are not standard automotive coils, but...
  8. H

    Calculating q factor of an inductor

    hmmm... I have tested several coils with this method and the results are textbook. I don't understand why I am not measuring the reactance. https://www.physicsforums.com/attachment.php?attachmentid=46145&stc=1&d=1334214699 Sorry for the crappy schematic, but I don't know how to do it...
  9. H

    Calculating q factor of an inductor

    Ok, I've tested a few with my method. They measure: 5.66K reactance 2.92K resistance Q 1.94 5.04K reactance 2.89K resistance Q 1.74 6.24K reactance 3.35K resistance Q 1.77 Does this seem correct? How can one test the Q of the primary? My method does not seem to work until I test...
  10. H

    Calculating q factor of an inductor

    Yes, good idea. Here is my plan. I will set up a circuit with the coil and a variable resistor in series. I will drive the circuit with an ac source (at 60 hz) and measure the voltage at each leg on the source to the point where the resistor and coil join together. I'll adjust the resistor...
  11. H

    Calculating q factor of an inductor

    I have some old ignition coils that I would like to compare. I have set the secondary to resonate with a .47 mf capacitor and these coils will resonate at 50 to 70 hz. The problem is, I can't really compare them as the center frequency is different on each. Is there a way to test their q...
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