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| Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#42
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Actually, you haven't provided anything useful along the lines of
"tips" and you avoided responding to a previous reply of mine....but anyway, what you say is interesting: You are wrong in assuming the current flows in only one direction O.K., then please let me know how current would not flow in only one direction in the following example: If the low peak of the sine wave (and the rest of the the sine wave for that matter) is "fully" above the "zero" reference point, then isn't it true that the current DOES NOT alternate? |
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#44
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Again, is the term "DC Sine Wave" problematic because it is
fundametnally wrong Yes. DC by definition is zero frequency Nice parse-job.....here's my original entire comment in context: Again, is the term "DC Sine Wave" problematic because it is fundametnally wrong OR is it problematic because it is at odds with conventional terminology and nomenclature You conveinently left out the "OR...." part. You actually proved my point that DC is DEFINED (i.e. by convention) as "zero frequency". Is it that weird to posit that the superior concept with respect to considering any signal as AC or DC, be the actual NET current flow? I could see your point if signals were classified as either "ZF" ("zero frequency") or "NZF" (non-zero frequency") but we are dealing with "DC" or "AC" |
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#45
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On Fri, 10 Jun 2005 21:33:11 -0700, Bob Penoyer wrote:
On Sat, 11 Jun 2005 04:12:52 GMT, "NSM" wrote: wrote in message groups.com... Again, is the term "DC Sine Wave" problematic because it is fundametnally wrong Yes. DC by definition is zero frequency. Um, no. DC is Direct Current, i.e., current that flows in one direction. For example, the output from a rectifier is DC but it certainly isn't "zero frequency." No, it is NOT DC. Sometimes when speaking casually people call it DC, but more often it will be called rectified AC. I agree with you that DC stands for Direct Current. But what is the logical meaning of that? Who knows. The bottom line is that when a waveform varies with time, it is NOT DC in popular useage. I'm setting followups to sci.electronics.design. --Mac |
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#46
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#47
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On Fri, 10 Jun 2005 21:10:04 -0700, jackbruce9999 wrote:
If the low peak of the sine wave (and the rest of the the sine wave for that matter) is "fully" above the "zero" reference point, then isn't it true that the current DOES NOT alternate? That is to say, that current only flows in one direction....i.e. "direct current"? Isn't it also true that if the low peak of the sine wave is -0.00001V then the sine wave results in current flowing in both direction (albeit for a nanosecond)....i.e. "alternating current".....I'm not arguing that my use of nomenclature is "pure" or conventional....but I don't see how it is fundamentally wrong, without merit, or lacking a reasonable basis..... To an electrical engineer, at least, DC means time invariant. I suppose DC and AC have become misnomers. For example, a sinusoidal Voltage waveform across an open circuit would be called AC even though no current flows. And the voltage across a battery's terminals would be called DC even if there is no load, and hence no current. If you talk to EE's, you will have to get used to them using the terms this way. I am not sure where to set followups to, so I guess I'll just post to all four groups, and leave followups unset. --Mac |
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#48
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On Fri, 10 Jun 2005 22:24:24 -0700, jackbruce9999 wrote:
I concede my terminology is anti-convention, and "wrong" (with respect to convention) BUT I disagree with you he but do not try to communicate with anybody, because they will misunderstand you If you were given a sheet of paper a week ago, with only the phrase "a fully DC sine wave" on it, and you were asked to come up with as many realistic possible meanings, I have to believe that you could have only come up with one (and rather quickly) If true, then your statement: But because of the convention we keep up with the old definition to allow a communication with others. would hold true about "a fully DC sine wave" with respect to convention/"old definition" but not with respect to "communication" or ambiguity....while not "pure" or conventionally correct, is there really any other possible interpretation of "a fully DC sine wave" and therefore wouldn't you agree that being a "hyper-stickler" on this point is really not justifiable? Again, isn't there more ambiguity (poorer communication) in your description: The signal would be said to have a DC-component (of the average value) and an AC-component (of the rms value minus the DC) versus: a "fully DC sine wave" versus "a partially DC-offset AC sine wave" Ban and others are trying to educate you. You are resisting fiercely. As I said elsewhere, DC and AC have become (or perhaps always were) misnomers. In electrical engineering circles, the terms can be applied to ANY signal, even if there is no current at all. DC can be thought of as the average value of a waveform, or the zero frequency component, or the offset, in case of a sinewave. Your term "DC sine wave" makes you sound ignorant of engineering terminology. If that is not a good enough reason for you to drop it, then maybe you should avoid future posts to sci.electronics.design, where many or most of the posters are electrical engineers. --Mac |
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#49
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The term DC sine wave is much like Magellan still claiming
the world is flat after he circumnavigated the earth. Your wave could be a sine wave with a DC offset voltage. Or what you are calling DC might be either a step function or an impulse. DC would make the capacitors and inductors irrelevant in your original question. Your question is about L, R, and C. Therefore DC is not part of the discussion. Now, what kind of waves (sine, exponential, step, impulse, etc) - waves singlely or combined - do you want to ask your LRC questions about? There is no possible answer if asking about a DC sine wave. Move on to ask about waves that really do exist. wrote: If the low peak of the sine wave (and the rest of the the sine wave for that matter) is "fully" above the "zero" reference point, then isn't it true that the current DOES NOT alternate? That is to say, that current only flows in one direction....i.e. "direct current"? Isn't it also true that if the low peak of the sine wave is -0.00001V then the sine wave results in current flowing in both direction (albeit for a nanosecond)....i.e. "alternating current".....I'm not arguing that my use of nomenclature is "pure" or conventional....but I don't see how it is fundamentally wrong, without merit, or lacking a reasonable basis..... |
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#50
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Go back to the original few posts to see how it got started....despite
being explicit about the specs of the wave, someone childishly objected to my casual usage of "DC sine wave".....would it have been objectionable had I used "a fully DC-offset sine wave"?......again, I've never claimed that I was using "official" or conventionally-correct teminology or nomenclature....I just really object that anyone would object to what I was saying, when its meaning was explicitly stated (using actual numbers) and the phrase "fully DC sine wave", although conventionly queer, is not at all cryptic or hard to figure out......if I were a chemist and someone said "200 degrees above the freezing point of water", I wouldn't mock them, just respectfully point out that it's more common to say "20 degrees above the boiling point of water".....I would consider the person ignorant of the conventional terminology, but I would consider the person dead-on if he were talking about 232 degrees F. |
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#51
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Go back to the original few posts to see how it got started....despite
being explicit about the specs of the wave, someone childishly objected to my casual usage of "DC sine wave".....would it have been objectionable had I used "a fully DC-offset sine wave"?......again, I've never claimed that I was using "official" or conventionally-correct teminology or nomenclature....I just really object that anyone would object to what I was saying, when its meaning was explicitly stated (using actual numbers) and the phrase "fully DC sine wave", although conventionly queer, is not at all cryptic or hard to figure out......if I were a chemist and someone said "200 degrees above the freezing point of water", I wouldn't mock them, just respectfully point out that it's more common to say "20 degrees above the boiling point of water".....I would consider the person ignorant of the conventional terminology, but I would consider the person dead-on if he were talking about 232 degrees F. |
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#52
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#53
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Thank you for your comment, but I respectfully disagree....I could
really care less if someone used the correct terminology in describing something, as long as I could understand what they were talking about....in fact, I run into this situation alot - I never, ever, correct the use of improper terminology (until the person is finished)....I find it to be stifling of the other person and the point they are trying to make.....thousands of times per day, people (in industry) with only high school diplomas (or less) in industry make absolutely brilliant observations and suggestions, but well over 80% of these are ignored, poo-pooed or brushed-aside, by people with advanced college degrees....many times, in part, due to the unsophisticated way in which the ideas are expressed.....it definitely is frustrating trying to understand what someone is saying when they use unfamilar or unconventional terminology, but it really can pay off big to suffer through it...... |
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#54
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#56
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#57
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I assume that you are meaning that you have 10vpp wave with 10vdc offset.
The answer is the latter, but the terminology that you are using is incorrect. It is not all dc. It IS a varying current with a dc component. The impedance must account for all factors. Leonard wrote in message ups.com... 2 questions about a fully DC Sine Wave....let's suppose you have a DC Sine wave which varies from +5V to +15V peak-to-peak going into a load with R, L, and C components..... Question #1: Is the load's impedance a function of R, L, and C (and wave frequency) or is it simply just R (i.e. Z=R)? In other words does non-resistive impedance (L + C) really only matter with an AC signal OR anytime voltage varies periodically (even if it is all DC)? Question #2: Would a "regular" negative peak detector ciruit, like shown he http://www.elektroda.net/cir/index/D...CTOR.htmgative work for the DC Wave described? Will it output +5V or do negative peak detectors only work for AC signals? Thank you. |
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#58
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cross posting corrected
It is not childish to correct something that does not follow convention and does not make sense. You have been given the answer to your question several times and continue to argue your terminology makes sense. Apparently you do not understand that dc has a specific meaning and a sine wave is not dc. You described a signal that had both as components. The effect on the dc component is the resistive part, the effect on the sine wave is the impedance part. Calculating the impedance has to account for the non-resistive effects. Leonard wrote in message oups.com... Go back to the original few posts to see how it got started....despite being explicit about the specs of the wave, someone childishly objected to my casual usage of "DC sine wave".....would it have been objectionable had I used "a fully DC-offset sine wave"?......again, I've never claimed that I was using "official" or conventionally-correct teminology or nomenclature....I just really object that anyone would object to what I was saying, when its meaning was explicitly stated (using actual numbers) and the phrase "fully DC sine wave", although conventionly queer, is not at all cryptic or hard to figure out......if I were a chemist and someone said "200 degrees above the freezing point of water", I wouldn't mock them, just respectfully point out that it's more common to say "20 degrees above the boiling point of water".....I would consider the person ignorant of the conventional terminology, but I would consider the person dead-on if he were talking about 232 degrees F. |
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#59
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wrote in message oups.com... I concede my terminology is anti-convention, and "wrong" (with respect to convention) BUT I disagree with you he but do not try to communicate with anybody, because they will misunderstand you If you were given a sheet of paper a week ago, with only the phrase "a fully DC sine wave" on it, and you were asked to come up with as many realistic possible meanings, I have to believe that you could have only come up with one (and rather quickly) On the other hand, given a sheet of paper with a drawing of your waveform on it, I don't think too many readers would have described it as "a fully DC sine wave". |
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#60
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wrote in message oups.com... Thank you for your comment, but I respectfully disagree Another irritating newbie habit you have is replying without keeping at least a pip of the message to which you are replying. |
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#61
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#62
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wrote: 2 questions about a fully DC Sine Wave....let's suppose you have a DC Sine wave which varies from +5V to +15V peak-to-peak going into a load with R, L, and C components..... Question #1: Is the load's impedance a function of R, L, and C (and wave frequency) or is it simply just R (i.e. Z=R)? In other words does non-resistive impedance (L + C) really only matter with an AC signal OR anytime voltage varies periodically (even if it is all DC)? Question #2: Would a "regular" negative peak detector ciruit, like shown he http://www.elektroda.net/cir/index/D...CTOR.htmgative work for the DC Wave described? Will it output +5V or do negative peak detectors only work for AC signals? Thank you. jackbruce9-- Dis thing dat yu gots with da "DC Sine Wave" speak'n make no cents to dis cat. Tut |
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#64
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Don Bowey wrote:
Here's one last tip to help you with the homework assignment I gave you earlier: You are wrong in assuming the current flows in only one direction. Indeed - depending on the configuration of the R, L, C combination there may no DC component *at all* and the current would be purely a.c. Graham |
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#66
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"Bob Penoyer" wrote in message ... On Sat, 11 Jun 2005 04:12:52 GMT, "NSM" wrote: wrote in message groups.com... Again, is the term "DC Sine Wave" problematic because it is fundametnally wrong Yes. DC by definition is zero frequency. Um, no. DC is Direct Current, i.e., current that flows in one direction. For example, the output from a rectifier is DC but it certainly isn't "zero frequency." The output of a rectifier contains both AC and DC. You put a filter on it to get close to pure DC. |
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#67
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On Sat, 11 Jun 2005 06:12:09 GMT, Mac wrote:
snip Yes. DC by definition is zero frequency. Um, no. DC is Direct Current, i.e., current that flows in one direction. For example, the output from a rectifier is DC but it certainly isn't "zero frequency." No, it is NOT DC. Sometimes when speaking casually people call it DC, but more often it will be called rectified AC. Rectified AC _is_ DC. Now you might say, But it has a lot of AC stuff riding on it and that makes it "rectified AC." Okay, so let's hang a large capacitor across the rectifier's output. Now, assuming there is some sort of load connected to the rectifier, there will still be ripple on the load--so there is still some AC present. Is this still rectified AC? Using your definition, when does the signal change from rectified AC to DC? I agree with you that DC stands for Direct Current. But what is the logical meaning of that? Who knows. The bottom line is that when a waveform varies with time, it is NOT DC in popular useage. As long as there is a finite load on the rectifier that I've described, anything less than infinite capacitance will permit some ripple to be present. So, since you say "... When a waveform varies with time, it is NOT DC in popular useage," then the signal will never become DC. The simple truth is that a current flowing in only one direction is, by definition, direct current. It might have AC riding on it, but if it's direction doesn't change, it's DC. |
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#68
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wrote in message ups.com... Let me try this: would you object to "a sine wave which (net) results in a current that only flows in one direction" Yes, I would object. You can't predict that without knowing the whole circuit. Connect your DC sine wave to a reactance and current (and energy) will indeed flow in both directions. |
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#69
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wrote: 2 questions about a fully DC Sine Wave....let's suppose you have a DC Sine wave which varies from +5V to +15V peak-to-peak going into a load with R, L, and C components..... Question #1: Is the load's impedance a function of R, L, and C (and wave frequency) or is it simply just R (i.e. Z=R)? In other words does non-resistive impedance (L + C) really only matter with an AC signal OR anytime voltage varies periodically (even if it is all DC)? jackbruce9-- You're getting a variety of answers because your input source shape is vague--because of the terminology--let me try to help, you pick whats best for your "DC sine wave." 1.Nonsinusoidal, nonperiodic source + RCL circuit--difficult to analyze--requires calculus, Fourier analysis, and Lapace transforms 2.Nonsinusoidal periodic source + RCL circuit--difficult to analyze--requires calculus and Fourier series 3.Sinusoidal source + RCL-- fairly easy to analyze--requires some work with complex numbers 4.DC source + RCL--not so easy to analyze--requires calculus and differential equations to understand what's really going over time 5.DC source + resistor only circuit--easy to analyze with algebra and ohms law, Kirkoff etc. So there you have it. Good luck Tut Question #2: Would a "regular" negative peak detector ciruit, like shown he http://www.elektroda.net/cir/index/D...CTOR.htmgative work for the DC Wave described? Will it output +5V or do negative peak detectors only work for AC signals? Thank you. |
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#70
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On Fri, 10 Jun 2005 20:28:09 -0700, jackbruce9999 wrote:
I would challenge you to prove that the term "DC sine wave" is objectionable because it is fundamentally wrong as opposed to being at odds with conventional terminology and nomenclature... This is clearly a sucker bet. Anyone with common sense knows that "conventional terminology and nomenclature" are already "fundamentally wrong." Notwithstanding there's no such thing as a "DC Sine Wave." It's like saying, "I'd like some red paint, but in blue." It's an oxymoron. (which I'd always thought was pimple cream for retarded people). "Since the sky is green, I guess I'll plant some bluegrass, and paint my house clear." -- Cheers! Rich ------ "The notorious Duchess of Peels Saw a fisherman fishing for eels. Said she, "Would you mind? Shove one up my behind. I am anxious to know how it feels."" |
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#71
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On Fri, 10 Jun 2005 20:59:03 -0700, jackbruce9999 wrote:
Right...but your reply actually doesn't address the NET effect......if the wave had a DC-component of +2 V and an AC-component of 10Vpp, then the wave would be NET AC (since its polarity changes pos/neg/pos/etc.)......however if the DC-component was +10V instead, then the wave would be NET DC (since its polarity never changes polarity - i.e. always positive).....that is why I argue a "fully DC sine wave" is a BETTER (albeit unconventional) and more concise way to describe what I'm talking about (without using actual values) than the conventional description you provided....your description is ambiguos...could be NET "AC" (biphasic) or "DC" (monophasic) Now, you're trolling. **** off and read a ****ing book. Then, ask in sci.electronics.basics, _after_ you "get" some BASICS. Sheesh! Rich |
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#72
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On Fri, 10 Jun 2005 22:24:24 -0700, jackbruce9999 wrote:
I concede my terminology is anti-convention, and "wrong" (with respect to convention) BUT I disagree with you he but do not try to communicate with anybody, because they will misunderstand you If you were given a sheet of paper a week ago, with only the phrase "a fully DC sine wave" on it, and you were asked to come up with as many realistic possible meanings, I have to believe that you could have only come up with one (and rather quickly) If that happened to me, I would snitch out the teacher to the principal, or snitch out the professor to the dean, because the teacher/prof is obviously incompetent, and has no business teaching wholesale bull**** to impressionable students. 'nuff said? Go read a _real_ book. Sheesh! Rich |
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#73
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On Fri, 10 Jun 2005 22:53:35 -0700, jackbruce9999 wrote:
I will absolutely buy what you said, but understand the import of what you're saying....you're saying that the language of "AC" and "DC" has essentially been somewhat *******ized from its original meanings to also mean zero-frequency and non-zero-frequency signals. Therefore, to describe a 10Vpp signal with a 10VDC offset as an "AC" signal is actually contrary to the original connation of "alternating current" since it (net) results in a signal which yields only a mono-directional (i.e. direct) current flow (albeit time variant). So in a sense, you could say I am holding "pure" to the original (circa 1890's) definition of AC/DC while its use has been "officially" corrupted to cover the concepts of "zero frequency" and "non-zero-freuency". Agree? I can't vouch for the historical facts, but as far as zero frequency and non-zero-frequency goes, you are pretty much correct. Another point to note is that many signals have both AC and DC. It is not a dichotomy. The signal you mentioned at the start of this thread has both AC and DC. Historically, I think what happened is that the terms originally were used to describe two competing power sources (the war between those who wanted a DC power grid and those who wanted an AC power grid was surprisingly fierce). Later, the terms started getting used to describe signals, and that is probably when the shift to the ZF- and NZF-meaning happened. Also, there may be people out there who still think of AC and DC in the original sense (I'm not sure about this, but maybe people who work with power stuff exclusively), but among electrical engineers, the signal perspective prevails. --Mac |
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#74
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On Sat, 11 Jun 2005 00:12:53 -0700, jackbruce9999 wrote:
Thank you for your comment, but I respectfully disagree....I could really care less if someone used the correct terminology in describing something, as long as I could understand what they were talking about....in fact, I run into this situation alot - I never, ever, correct the use of improper terminology (until the person is finished)....I find it to be stifling of the other person and the point they are trying to make.....thousands of times per day, people (in industry) with only high school diplomas (or less) in industry make absolutely brilliant observations and suggestions, but well over 80% of these are ignored, poo-pooed or brushed-aside, by people with advanced college degrees....many times, in part, due to the unsophisticated way in which the ideas are expressed.....it definitely is frustrating trying to understand what someone is saying when they use unfamilar or unconventional terminology, but it really can pay off big to suffer through it...... Well, look at it this way: almost all of us had to read your post twice and think about it to make sure we understood the most likely meaning of it. If you worded it differently, the meaning would be crystal clear, and we would only have to read it once. So in a sense, it is inconsiderate and a waste of our time to post it in such a way that we can't immediately understand. You can easily be forgiven for doing this once out of ignorance. Anyway, I agree that some people were rude to you. But you haven't exactly showed yourself to be receptive to advice, either. --Mac |
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#75
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wrote in message ups.com... Let me try this: would you object to "a sine wave which (net) results in a current that only flows in one direction" if you buy that, would you then accept it to be partially condensed into: "a sine wave which (net) results in a non-polarity-alternating current" if you buy that, would you then accept this: "a sine wave which (net) results in a direct current" and then "a (net) direct current sine wave" I object to all of the above. Go read Scroggie's "Second thoughts on Radio Theory". N |
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#76
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"Mac" wrote in message news 
Historically, I think what happened is that the terms originally were used to describe two competing power sources (the war between those who wanted a DC power grid and those who wanted an AC power grid was surprisingly fierce). Later, the terms started getting used to describe signals, and that is probably when the shift to the ZF- and NZF-meaning happened. Pretty much. Even in other languages I believe that terminology is basic - certainly German is the same (Gleichstrom. Wechselstrom.) N |
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#77
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#78
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If you learn the math the definition of AC and DC is totally irrelevant.
Your original Question #1 indicates that you don't know the math. That is fine; it is something you can learn, but no amount of quibbling over semantics is going to change the principles of circuits. Forget the encyclopedia, learn differential equations instead. Encyclopedia are for junior high school kids. wrote in message oups.com... I will absolutely buy what you said, but understand the import of what you're saying....you're saying that the language of "AC" and "DC" has essentially been somewhat *******ized from its original meanings to also mean zero-frequency and non-zero-frequency signals. Therefore, to describe a 10Vpp signal with a 10VDC offset as an "AC" signal is actually contrary to the original connation of "alternating current" since it (net) results in a signal which yields only a mono-directional (i.e. direct) current flow (albeit time variant). So in a sense, you could say I am holding "pure" to the original (circa 1890's) definition of AC/DC while its use has been "officially" corrupted to cover the concepts of "zero frequency" and "non-zero-freuency". Agree? |
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#79
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"Pooh Bear" wrote in message ... wrote: .see also this previous thread where someone else uses the same terminology ("DC sine wave").... Just because someone else used the term doesn't make it right ! There's plenty of rubbish spouted on the net. Graham Once in a while someone coins a new term like Heinleins' waldo... but I don't think its going to happen here. What has been described is similar to the waveform one would see on the grid of a class A tube circuit. (but negative voltage of course) There are a number of waveforms that go in only one direction relative to ground such as sawtooth waves, square waves, and triangle waves. To refer to these as say a "DC triangle wave" would be equally confusing without further qualification. The closest descriptor that I can think of offhand that might meet with general acceptance would be "bias signal". |
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#80
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wrote:
Again, is the term "DC Sine Wave" problematic because it is fundametnally wrong OR is it problematic because it is at odds with conventional terminology and nomenclature.....if it is fundamentally wrong, then please show how.....however, if we're just talking about convention, then why break balls? (Wait, I'm sorry, I don't mean literally "breaking balls", that's just nomenclature).....if you were given a piece of paper a week ago with just the words "A Fully DC Sine Wave" on it and you were asked to come up with as many possible things it could realistically mean, how many things could you come up with? If you were being truthful I think you could only think of one thing (and think of it very quickly). If you think that the term "fully DC Sine Wave" even means anything, then you have not understood the coursework. ------------- Don't freak out, a sine wave with a DC offset so that it is all pulsating DC is not at all unusual, every transistor amp has one since transistors can only accomodate one polarity of current. -Steve -- -Steve Walz ftp://ftp.armory.com/pub/user/rstevew Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!! http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public |
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