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Understanding Electronics Basics #1

Discussion in 'General Electronics Chat' started by cowboybob, Feb 16, 2012.

  1. Muttley600

    Muttley600 New Member

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    WHAT! You mean there's shelves with more on *grin*
    What's on em :)

    Don't forget we haven't covered phase or db properly yet
     
  2. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    You betcha. And we're gonna be on analog for a while. Wait til we venture into digital country: vast and wild and wooly. But that's a ways off.

    For now, let's discuss phase.

    First, though, I'd like to ask you a question.

    Do you realize that the sine-waves (and square and triangular and sawtooth, etc. waves) we've been discussing move? Not just up and down (amplitude), but from (for the sake of the argument) left to right from source to load (and back), sort of like a wave on the ocean? That is to say. from your vantage point, standing there looking at a power line, that a sine-wave is zipping along the wire at the speed of light? The fact that they move is critical to the concept and understanding of phase. This is because phase is, in essence, all about timing, which implies motion.

    You may already understand this concept. If so, forgive me. But I have to ask, since phase cannot be understood without this basic foundation.

    I await your response.
     
    Last edited: Mar 24, 2012
  3. Muttley600

    Muttley600 New Member

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    Morning CBB, you'll be pleased to hear that I understand waves move back & forth

    Sim shows them moving on auto setting instead of single, although it seems like they move left to right, I take it we just cannot see the oscillation due to speed of it implying that there is two movements, oscillation/general movement from pole to pole

    Edited: just to be sure, cap charges on forward motion & discharges on other, just so you know I understand :)
     
    Last edited: Mar 24, 2012
  4. dave

    Dave New Member

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  5. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Correct. Thank you.

    OK, then, let's look at phase.

    This will be, initially, short but it should demonstrate the how and why of phase. No math here, just the phenomenon.

    Also, understand that ANY sine-wave (in the case) is composed of both a voltage component AND a current component. They are both in perfect "sync" as they come from the VG.

    This is a resistive circuit in which no phase "shift" occurs. In a simple resistive circuit the phase of the signal sources are the same for both voltage and current. They instantaneously occur at the exact same time. Resistance, all by its lonesome, has NO effect on phase.

    View attachment 62586

    This, however, is a capacitive only circuit where the capacitor, due to it's charging characteristics, forces the current wave to"peak", or go immediately to the maximum the circuit will allow, while the start of the voltage wave is still at zero. I realize this will strike you as impossible, but these things happen instantly, and the math backs that up.

    The graph shows a slight "hesitation" in the very first current peak but that's an anomaly of the sim. For the math of this, peak current is instantaneous at time zero of the start of the sine-wave. And note that the timing of the peak of the voltage of the sine-wave is 1/4 of it's wavelength later, or 90°. The voltage sine-wave is 90° out of phase with the current sine-wave.

    View attachment 62587

    Now here' a resistive/capacitive circuit. Note the phase difference. Can you explain this (comparing it the the previous two)?

    View attachment 62588

    Tell me what you think.
     
    Last edited: Mar 24, 2012
  6. Muttley600

    Muttley600 New Member

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    Ok, differences between sim 2&3 caused by adding R

    R has lowered the VP to 9.54 meaning there is less force, so it slowed the VP wave by 1m, hence changing the phase

    I slowed to allow charge time for cap before carrying on as normal, hence not changed instantly but by slowing I wave down we have lost some output (by resistance) but charge time has resulted in phase shift too

    Ok, does this alter the frequency then, Giving us the db gain as its going in opposite direction to wave?

    What other toys can I pick up, look, what's that one on the middle shelf.lol
     
    Last edited: Mar 24, 2012
  7. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Yes.

    First, what's the "VP" wave? If you mean the VG wave, the yes.

    Assuming that by VP you mean VG, well, yes, but with a change: it didn't slow the VG wave, it slowed the rate of change of the cap (and thus the phase), as you state in the next quote.

    The current isn't slowed ever, for all intents and purposes. But the RC time constant factor has slowed the charging timing with respect to the source (VG) timing.

    Again, I is not slowed: the timing is is delayed. But the rest is correct.

    No. In this example the frequency is not changed by the circuit. Only the phase. Were this circuit a timing element of a more complex oscillating circuit, then yes, it would change the frequency.

    dB is a circuit gain measuring value. It has no bearing on frequency. Frequency DOES, however, have a bearing on dB gain (or loss).

    We'll deal with dB in the next "e-school" session.

    It's a 10 megawatt magnetron used in phased array, target acquistion, warship fire (weapon) control systems with an effective range in excess of 400 nautical miles. You don't want to play with that puppy just yet...
     
    Last edited: Mar 24, 2012
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  8. Muttley600

    Muttley600 New Member

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    By using VP I was meaning voltage potential, the energy able to move the electrons, is that the same as VG? It has to be the same (this is no longer a question) I need to start believeing what I'm saying

    So I need to think of this as a time delay rather than speed of wave slowing down, I get what your saying :)
    How could I have thought of it as slowing, that would affect the frequency, man I'm a numpty

    I also see why I needed to be able to see the three elements, there are differences, this is just the start time of a wave

    Will wait to do db after getting this right :)

    Ok, I'll leave that toy on the shelf, don't want anyone getting hurt.lol

    So amplitude is power of signal
    Frequency is how fast/speed of oscillations is over distance Edit: determined by how much charge is allowed through the cap
    Phase is time delay to start of wave or how much charge before oscillation turns direction

    So the cap is not only being delayed but also how much it is allowed to resonant
    We are about to come back to those five charge times you mentioned ages ago aren't we :)
    So we can set the height (width of spring coil)
    Length of spring coil
    & decide when to fire the starters gun on a wave or release the coil

    That's it, I really have finished editing now.lol
     
    Last edited: Mar 24, 2012
  9. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    I see what you're saying. VG is just the Voltage Generator. Speaking of which, can you tell me, from the data you have, what is the frequency of the signal coming from the VG?

    Yes.

    (My emphasis)

    "The start time of a wave" with respect to time zero. Generally applicable when considering its phase in relationship to another wave or event (such as a simple trigger pulse).

    (Emphasized addition is mine)

    Yes to all, with the phase caveat in the sentence above this quote.

    Yes. Except (assuming we're talking a fixed [unchanging] frequency) with this change to "Length of spring coil" statement: Length of one complete turn (360°s) of the spring coil when the entire coil is stretched to a particular length.

    Good job, Graham.
     
  10. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    As to your edit(s):

    Not through the cap, into it.


    See post #506.

    The charge into the cap is being delayed.

    I may be misunderstanding what you're saying (thinking), but go back and look at the original images as we took on discussing phase. Notice how the VG sine-wave is unchanged in every example.

    Here is a block diagram of the process (these often help break down a process into more manageable concepts):

    Block of Circuit:
    View attachment 62596

    Made up of blocks of VG, then RC circuit, then Output (flow is obviously from left to right):
    View attachment 62597 View attachment 62598 View attachment 62599

    VG is a "fixed" source: it does not change (unless YOU change it). It's wave on the graph is taken directly from the VG.
    The RC circuit fundamentally alters the input from VG, not the other way around.
    And the the Output merely reflects that change.

    These circuits was meant to demonstrate that the phase of the voltage going through just a capacitor circuit is not changed by it, but the current going through that circuit DOES have its phase changed. We are really ignoring amplitude changes, other than to note the effect of the resistor's normal reduction.

    It's the RC circuit that then CAN and does change the phase of the voltage going through it.

    Oops. What did I say?...
     
    Last edited: Mar 24, 2012
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  11. Muttley600

    Muttley600 New Member

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    I knew my coil was a good idea look, we even have radians on it.lol

    Ok, here's what I think, that doesn't make it right.eek!

    10V coming from VG with 1A load (please don't tell me it's 20v with 2A load or that will mess with my head.lol)

    We have a total of 5.86 ma load on circuit

    We have a 1k R * 1u cap = 0.001ms delay on V&I

    VG = 90degrees = 5m * 4 (360) = 20ms period

    1F = 1/0.024ms = 50 kHz frequency

    I enjoyed that, it might all be total tosh but I enjoyed it anyway.lol
     
    Last edited: Mar 24, 2012
  12. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Terminology:
    In electronics Power is V * I and the other formulas and it has units of Watts. Furthermore dissipated power has a positive sign and generated power has a negative sign at least for analysis.
     
  13. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Yes. Excellent. A++

    One small observation in this equation:

    [QIOTE=]VG = 90degrees = 5m * 4 (360) = 20ms period[/QUOTE]

    The portion: "5m * 4 (360)" would read, "5m times 4 times the quantity 360". That portion in the "()"' marks I'm assuming means 360°s, but parentheses in a formula indicate a "quantity to be multiplied by". Just being nit-picky, but with math you gotta be.

    Anyway, good job.
     
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  14. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Good catch, KISS.

    Thanks.
     
  15. Muttley600

    Muttley600 New Member

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    WHAT! You mean I got it right, must be down to the brilliant teacher I have :)

    Your gonna think this is weird, but I like you both nitpicking, it helps my understanding, but more importantly, it means there's nothing more major to fault.lol

    Just having read back over post #509

    What does the phase alteration do in terms of I, none I imagine, other than timing of start to load?

    You mentioned many moons ago about there being 5 different aspects in percentages on the way to full charge of cap
     
    Last edited: Mar 24, 2012
  16. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    OK, here is a question for you:

    Somewhere on the planet Earth, there is a place that receives 6 hours of daylight in a day. The amplitude just so happens to be the intensity of the AM 1.5 Global spectrum.

    What is the frequency?

    What is the duty cycle?

    Showing your work is more important than a number. Units matter.
     
  17. Muttley600

    Muttley600 New Member

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    Ok, I get the 1/4hz & 25% duty cycle but why did you put the amplitude In there......to show me that without correct term you can't work out the numbers?

    So, a term to say V & I for sim should of been?
    So are you saying any load as a whole should be referred to as Watts
     
    Last edited: Mar 24, 2012
  18. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    1/4 Hz = Every 4 seconds so your answer makes no sense.

    Questions on exams always put information that isn't relevent. You had to know that the number of hours in a day is 24. So 6 h/24 h is 0.25 or 25%. The 24 wasn't in the problem. AIR MASS 1.5 Global isn't necessary either. I could have said 10 V l represents 100 mW/sqcm. In the real world, your not fed the information you need.

    I didn't expect you to get the frequency right, primarily because of lacking the concept relating to conversion of units.

    Amplitude would have been fine. So would p-p.

    Not necessarily take light bulbs (Watts), generators (VA), speaker loads (Ohms) and motor loads (HP) (We haven't covered them)
     
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  19. Muttley600

    Muttley600 New Member

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    Not helped by readings in rms on multimeters compared to sim readings, although they can be worked out


    Oh that's an easy excuse.lol the more I use them the easier it becomes (read hopefully)

    Let's not forget before Xmas I hadn't even heard of u/m etc in my world, it is only now that I'm starting to see what they actually mean & relate to, even now I'm using a table to see how many zeros are in a answer (I'm being honest here) but ican tell you off the top of my head while i have this smoke that milli stands for thousand 0.001 & u stands for million 0.000 001, so I am starting to remember them :)

    I'll get there, don't you go giving up on me just yet
     
    Last edited: Mar 24, 2012
  20. Muttley600

    Muttley600 New Member

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    Ok, for amusement factor & to prove I can still mess things up as good as I ever did, try this

    Frequency of 6hrs = 1.28 uHz
     
  21. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    What does 6 have do do with the problem?
     

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