Wikipedia:Featured article candidates/Mechanical filter/archive1

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The following is an archived discussion of a featured article nomination. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article candidates. No further edits should be made to this page.

The article was promoted by Karanacs 21:46, 3 November 2010 [1].

Mechanical filter[edit]

Mechanical filter (edit | talk | history | protect | delete | links | watch | logs | views)

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Nominator(s): SpinningSpark 16:57, 17 September 2010 (UTC)[reply]

I am nominating this for featured article because it is a great article. It is a sister article to distributed element filter which has previously achieved FA. Mechanical filters are an alternative method of achieving the same thing in electronics. The article follows a similar structure and style to the DEF article and where there was doubt, the already promoted DEF article was consulted as a template. Mechanical filter has undergone a Good Article review with user Materialscientist, a Peer Review with users Finetooth and Catslash, an "unofficial" Peer Review with user Ruhrfisch and a "line-by-line" review from user Cryptic C62 SpinningSpark 16:57, 17 September 2010 (UTC)[reply]

Comment. No problems with dablinks or deadlinks. PL290 (talk) 17:08, 17 September 2010 (UTC)[reply]

I support this FAC in terms of the article's clarity and accessibility. --Cryptic C62 · Talk 21:30, 17 September 2010 (UTC)[reply]

Oppose

—Preceding unsigned comment added by Sturmvogel 66 (talk • contribs) September 18, 2010

Sources comments: Re the above anonymous entry, it is surely unnecessary to oppose on the grounds of nitpicks of this nature. The use of "Taylor & Huang" in the cites is not contrary to MOS policy per the link provided; so far as I can see all the books have publisher locations; the paging in cite 3 is presumably a reflection of the book's pagination and I don't see it as confusing. The one point that I would like to comment on is the use of "second-hand" cites. Are these reprints of the original article, or quotes from them? If the latter, is it not possible to obtain copies of the originals and to cite them directly?

Otherwise, sources look OK. Brianboulton (talk) 09:10, 18 September 2010 (UTC)[reply]

  • Title in references... The titles of articles or book chapters are in sentence case and the titles of journals or books are in title case in conformity with WP:CITE/ES. This is also in conformity with the template article, distributed element filter, this issue was discussed at that article's FAC and the format accepted. Simplistically, the part between "quote marks" should be in sentence case and the part in italics should be in title case.
  • Ampersands... I was about to change this, but in view of Brian's comment above it does not now seem necessary. Note that the ampersand is only being used in the short-form in-line cites for brevity and not in the full citation.
  • As Brian stated, all the books as far as I can see have place of publication. Please state the exact references you think are at fault. Or did you mean that sources other than books need place of pubication? That would not conform to WP:CITE/ES.
  • ...cite #3. The page numbers are given in this form for clarity. The source actually paginates as 1-85 for example. However, using a dash in the reference would be very confusing since dashes are usually used for page number ranges. Using the dash for this purpose though, would also be confusing for anyone trying to look up the reference and finding dashes in the pagination. I have no particular attachment to this and will happily change it if that is the consensus.
  • SpinningSpark 10:46, 18 September 2010 (UTC)[reply]
  • ..."second-hand" cites. Not entireley clear what is being referred to here. If cite #12 is an example, this is not exactly a quotation nor is it a reprint. The claim being verified is that Firestone first presented the mobility analogy. The secondary source used to verify this claim is Pierce. Pierce cites Firestones paper as the primary source. Firstly, it would be wrong to replace the secondary source with a primary source as this would contravene WP:PSTS. Secondly, it is quite unlikely that Firestone would categorically make the claim of being first in his paper and a secondary source is needed to provide this synthesis. The primary sources are not strictly necessary to meet WP:V and could all be removed, however, they are conceivably useful to readers who may be looking for precisely that. It would be wrong to put them in as "stand-alone" cites since they have not been read (by me) so I have used the construction "secondary source page x cites primary source". Open to suggestions/criticisms on this. SpinningSpark 11:19, 18 September 2010 (UTC)[reply]
  • Good explanation, and I'm happy to leave them be. Brianboulton (talk) 22:54, 18 September 2010 (UTC)[reply]

Support FAC nomination per above. --Alan the Roving Ambassador (talk) 17:55, 19 September 2010 (UTC)[reply]

Per what above? Please clarify what you have reviewed, and why you believe the article meets WP:WIAFA. SandyGeorgia (Talk) 14:21, 23 September 2010 (UTC)[reply]
  • The formulae in the Elements section should be laid out using <math> markup. Stifle (talk) 20:39, 20 September 2010 (UTC)[reply]
    • Sorry, previously overlooked these two comments tucked in here. The formulae in the table are typeset with LaTeX. To what are you referring? SpinningSpark 22:30, 22 September 2010 (UTC)[reply]
      • Never mind; my preferences are off. Stifle (talk) 21:13, 1 October 2010 (UTC)[reply]
  • Is it usual to mark images "figure 1/2/3/etc."? Stifle (talk) 20:39, 20 September 2010 (UTC)[reply]
  • Support and comments. Well written, although I wouldn't claim that I understood every word!. Two minor quibbles:
  • In the formula table, a, j, ω and C appear to lack definitions. I'm guessing that a is acceleration and C is capacitance, but there's nothing to tell me that, and I don't have a clue what the other two are unless j is the same as i
  • Yes, j is the same as i. For a more technical article I would tend to use i, but for this article I have used j because the target audience is likely to have a little electrical theory but not necessarily strongly mathematical and j is used universally in teaching electrical engineering. I have added definitions for C and jω. The formula itself implies that a=dv/dt, which is the definition of acceleration so this hardly seems necessary. SpinningSpark 18:33, 24 September 2010 (UTC)[reply]
  • Eclairage Electr., Journal titles should be written in full

Good luck, Jimfbleak - talk to me? 10:23, 23 September 2010 (UTC)[reply]

Support I "peer reviewed" this and almost all of my issues were addressed then. I find it meets the FA criteria and am glad to support. *The dimensions in the caption of the lead image should be given in inches as well as mm per the MOS.

  • I think all of the variables in the table in Elements need to be defined (x, t, a) and for the matrix in Mechanical equivalent circuits, i.e. you could add them to the earlier sentence: ...equations relating electrical variables (voltage, v, and current, I) to mechanical variables (force, F, and velocity, V).
  • Does Footnote 1 need a ref too?

Nicely done, Ruhrfisch ><>°° 00:56, 29 September 2010 (UTC)[reply]

Thanks. I removed velocity from the note you added as v was already defined. I also would be fine with the inches being given as decimals instead of fractions in the caption, but this is your call. Ruhrfisch ><>°° 11:26, 1 October 2010 (UTC)[reply]
Not really convinced that there's anyone out there who can't grasp 45 mm anyway, but if we are going to have inches for the people who grew up with them, then there is only any point if it's done the way they are used to, which means fractions. SpinningSpark 15:29, 1 October 2010 (UTC)[reply]

Oppose, soley on the basis that the introduction does not provide an accessible overview of the article, under Wikipedia:Lede#Provide_an_accessible_overview. While the subject undoubtedly is technical, the introduction should tell the average reader what this is, what it does, and why that is important. Ideally, that overview should be in the first paragraph. While the first sentence to Electronic filter is perhaps too detailed, it does tell us that such filters "remove unwanted frequency components from the signal, to enhance wanted ones, or both". Something similar should be stated here, and why that matters to, for example, a radio listener. Kablammo (talk) 16:29, 1 October 2010 (UTC) stricken, given edit described below. Kablammo (talk) 20:43, 7 October 2010 (UTC)[reply]

I have added to the first paragraph a sentence more or less identical to a sentence in the already promoted sister article distributed element filter which addresses what it does. Its importance is mainly concerned with the high "quality factor" obtainable and is already covered in the lede, together with the major application and reason (selectivity), although admittedly, not in the first paragraph. SpinningSpark 18:54, 7 October 2010 (UTC)[reply]

Comment (Spinningspark drew my attention to this FAC review after I participated in the FAC review for distributed element filter and in the peer review for mechanical filter). I have a slight knowledge of distributed element filters, but know nothing of mechanical filters, and so cannot judge (for example) whether this article is comprehensive. It does meet the FA criteria as far as I am aware though. On rereading the article, a couple of points occur to me:

  • In the transducer diagram (figure 4): (1) The piezoelectric material is shown with a single electrical contact, presumably there is a second electrode? (2) It would be nice to have the blue-red arrows to identify the coupled mode as in figure 5. The text does explain the mode, but requires some effort on the part of the reader. Actually it'd be nice to have the blue-red arrows in all relevant figures. (3) The colour used to identify the ferrite is too close to the colour for the resonators (in the actual diagram - it's sufficiently distinct in the key). Not sure whether it would be obvious to everybody which was which.
  • If the Q and stability are so high, do the filters need individual trimming to hit their nominal centre frequency? Or does it not matter if the actual frequency differs from the nominal value (in the IF application)? (Google very quickly found me Mohamed A. Abdelmoneum, Mustafa U. Demirci, Sheng-Shian Li, and Clark T.-C Nguyen Post-Fabrication Laser Trimming of Micromechanical Filters)

--catslash (talk) 00:36, 2 October 2010 (UTC)[reply]

  • Transducer diagram
  • second electrode. The definition of "electrode" is a conductor connected to a non-conducting material. Technically speaking therefore, there is only one electrode per transducer. However, I am guessing that is not really your question and the real question is "where is the return path conductor?" This might be connected to the resonator, if it is metal and there is a convenient anchor point, but more likely it is connected to the metal chassis or framework and so is correctly not shown on the transducer diagram.
  • blue-red arrows. I don't really want to start major rework of the diagrams at this late stage after so many reviews. A different approach might have been considered if it had been discussed at GAN or Peer Review but I feel the diagrams we have best suite the article as it is now structured. my reasoning is primarily that this is an overview article with diagrams that are clean and simple. It is not necessary to clutter them with every detail of a design. Figure 4 is intended to show the differences between transducer types and information on it is limited to that purpose. Likewise, figure 5 is intended to show the differences between vibration modes. To show arrows for the vibration modes on every other diagram would make figure 5 pretty much redundant. Further, before one can start putting arrows on resonators, knowledge of anchor points (equivalent to sc or oc stubs) and whether a higher mode (number of nodes) oscillation is taking place needs to be provided. The diagrams would need to have this information added as well and probably the dimensions of resonators adjusted to make the it work for that mode number. I feel this would start to unduly clutter the diagrams. However, more detailed diagrams might be appropriate for articles on individual circuit types and I will happily provide such diagrams for any editor who wants to work on an article.
  • ferrite colour. I'll try and adjust this to give a better contrast. This is probably highly dependant on monitors; it looks fine on mine (viewed on two computers and three different monitors) but as I say, I'll try to get it better.
  • individual trimming. Yes, they do need trimming. Japanese manufacturers are supposed to have trimmed the resonators with needle files on test before sealing. This could go in if it were sourced, but none of my sources discusses it. It is quite possible that laser trimming was done in later production, but the source you mention is for a MEMS device which is quite a different beast. I'll do a search for sources, but I can't promise anything is going to turn up.
  • SpinningSpark 20:10, 7 October 2010 (UTC)[reply]
  • I have created something in sandbox on this. Comments would be appreciated before it goes in the article. SpinningSpark 13:58, 9 October 2010 (UTC)[reply]
You seem to have found plenty of material on trimming. One tiny reservation I have is about ascribing the necessity for trimming to the The precision applications in which mechanical filters are used (first sentence). I'd say it was just handy in building the filter to the have the fractional error in the resonator frequencies << 1/Q (irrespective of what you do with the finished filter - it was the high Q that made me ask about trimming). This is difficult to state clearly in non-technical terms; the best I can manage at the moment is Mechanical resonators can select a frequency so precisely, that any small frequency shift caused by manufacturing inaccuracy is significant, and so the resonators must be individually tuned. This is known.... Not perfect I realize, so I'll understand if you prefer not to use this (or if you have to drop the so).--catslash (talk) 21:13, 10 October 2010 (UTC)[reply]
I don't think that is entirely accurate technically, or rather, it is not applicable here. I'll drop a note on your talk page rather than clutter here with a long explanation. SpinningSpark 23:10, 10 October 2010 (UTC)[reply]
Yes, my sentence suggests that it's the unloaded Q of the individual resonator that's important. I shan't make a second attempt at it, and I retract my reservation.--catslash (talk) 23:52, 10 October 2010 (UTC)[reply]

Comments. The prose appears generally good, but I have some concerns about cohesiveness and flow. The lead seems too detailed to summarize the article, and seems to lack coherence. For example, the second paragraph gives rise to several questions:

  • The components of a mechanical filter are all directly analogous to the various elements of an electrical circuit. It is therefore possible to apply electrical network analysis and filter design techniques to mechanical filters. This aids electrical engineers when they are designing such circuits. With the right choice of component values it is possible to produce any of the classic frequency responses. Steel and nickel-iron alloys are common materials for mechanical filter components; nickel is sometimes used for the input and output couplings.
    • First sentence: what electrical circuit? One for a filter, or any circuit?
    • Second sentence: "It is therefore possible ...". Unclear why "therefore", at this summary level, and probably unencyclopedic.
    • Third sentence: relevance unclear; article is not about those circuits, and a surprising jump from design of mechanical filters to design of electical circuits. If such aid is one of the main reasons mechanical filters are important, that needs spelling out here.
    • Fourth sentence: the reader has no basis to understand what is meant by any of the classic frequency responses
    • Fourth sentence: the reader has no basis to understand whether the sentence is about mechanical or electrical filters.
    • Fifth sentence: to end the para, why the leap to a seemingly unrelated statement about the metals used in a mechanical filter?
  • Then, in the the fourth para of the lead, we read that "By the 1950s mechanical filters were being manufactured as self-contained components for applications in radio transmitters and high-end receivers. Their greatest attraction was the high "quality factor" Q that mechanical resonators could achieve, far higher than an all-electrical LC circuit. Mechanical filters can consequently be built with excellent selectivity characteristics, an important performance measure in radio receivers."
    • "By the 1950s ... Their greatest attraction was ... Mechanical filters can consequently be built ..." Consequently?

This is a sampling only and not an exhaustive list. PL290 (talk) 20:26, 6 October 2010 (UTC)[reply]

Taking that point-by-point:
  • First sentence: this is a general observation that a mechanical system and an electrical system may be analogous, not only in exhibiting similar overall behaviour, but also in having a one-to-one correspondence between their constituent parts. If I have succeeded in clarifying that, could you suggest how this sentence could be amended to convey this unambiguously to a general audience?
  • Having understood the first sentence, the therefore of the second should now seem natural (?).
  • And having followed the reasoning of the second sentence, the relevance of the third may now be clear. Working backwards 3-2-1: if you can design an electrical filter, then you can design a mechanical one to do the same job, because you can build a mechanical system in which each part corresponds to a component of your electrical filter.
  • Fourth sentence: classic response: fair point.
  • Fourth sentence: so this is just saying that theoretically, what you can do in one medium, you can do in the other. This is just expanding on the third sentence; the two could be joined with a semi-colon.
  • Fifth sentence: fair point; new paragraph wanted.
  • Fourth paragraph: The excellent selectivity follows from the high Q, not from the decade of manufacture. Perhaps: The high Q that mechanical resonators can attain, far higher than that of an electrical LC circuit, made possible the construction of mechanical filters with excellent selectivity. Good selectivity, being important in radio receivers, made such filters highly attractive.
--catslash (talk) 22:13, 6 October 2010 (UTC)[reply]
  • Your last bullet (high Q rewording) is a definite improvement. All the rest, about what you can do in one medium you can do in the other, remains a problem and I'm unable to suggest wording because I simply can't tell what main point it intends to make. These are the opening sentences of the lead of the mechanical filter article; what major, central point are they trying to tell me about the significance of mechanical filters? PL290 (talk) 09:26, 7 October 2010 (UTC)[reply]
  • The main point (perhaps even the essential point of this article) is that there is a great body of theory associated with electrical filters, and electrical networks in general. By transferrring all this theory into the mechanical domain it suddenly becomes possible to do all sorts of clever things with mechanical parts that would otherwise not have been possible, or at least, would have required parallel mechanical theories to be developed first. Right now I am working on the diagrams, I will take a closer look at your individual comments later. SpinningSpark 20:28, 7 October 2010 (UTC)[reply]
  • This appears to be a main point about electrical filters, not mechanical filters. PL290 (talk) 12:02, 9 October 2010 (UTC)[reply]
  • To respond to your query about therefore, the point that I'm making is: following a statement with It is therefore possible ... asks the reader to follow a process of deduction, which reads like an essay, making it somewhat unencyclopedic—particularly in the lead. PL290 (talk) 12:02, 9 October 2010 (UTC)[reply]
  • That electrical network theory can be used to design mechanical filters, could be an observation regarding either circuit theory or mechanical filters depending on the context. Not sure what leads you to think otherwise.
  • Suggest This makes it possible.... However this results in serial thises with the next sentence This aids electrical engineers... which sounds a bit lame -so I would then ditch this subsequent sentence, which is anyway next to redundant, being near-enough implied in the preceding one. --catslash (talk) 15:44, 9 October 2010 (UTC)[reply]
  • The second para of the lede now reads,
The components of a mechanical filter are all directly analogous to the various elements found in electrical circuits. The mechanical elements obey mathematical functions which are identical to their corresponding electrical elements. This makes it possible to apply electrical network analysis and filter design techniques to mechanical filters. Electrical theory has developed a large library of mathematical forms that produce useful filter frequency responses and the mechanical filter designer is able to make direct use of these. It is only necessary to set the mechanical components to appropriate values to produce a filter with an identical response to the electrical counterpart. Steel and nickel-iron alloys are common materials for mechanical filter components; nickel is sometimes used for the input and output couplings.
This should address most of the comments from PL290. I have removed the "therefore" as suggested, but I challenge the idea that requiring a process of deduction is unencyclopaedic. I am fairly sure that this is not stated in any guideline. Besides, a natural question readers coming to this article will want answered is "how on earth is it possible for a mechanical assembly to function as an electrical circuit?" Answering this requires a "therefore" or a "because" in the article (depending on which way round it is stated) and any other way of stating it is merely a semantic disguising of these words.
I agree the final sentence is a quite abrupt change of topic (although arguably the para is talking about components all the way through). However, putting a para break in there is going to leave a one-sentence orphan. A possible solution may arise from the request by Catslash, above, to add material on trimming, for which there is a link, also above, to a sandboxed draft. If this is added to the article it will also require a summary sentence or two in the lede, which more naturally combines with the sentence on materials.
PL290, you complain that the lede is too detailed, but many of your comments require an expansion to give further explanation...
SpinningSpark 18:12, 9 October 2010 (UTC)[reply]

Questions and comments. Each re-reading suggests more questions, that I feel might or should be addressed. Sorry if this is never-ending.

  • The lede explicitly restricts the article to mechanical filters with electrical ports, but does not exclude all-piezoelectric or piezoelectric-substrate technologies. However, the latter get less of a mention than do mechanically coupled filters. For the article to be considered comprehensive, its scope may need to be more tightly defined.
  • The history section describes the rise of mechanical filters, but what happened next? Have they been superseded by related (quartz, piezoelectric ceramic, SAW) technologies, or by unrelated ones, or are they still as popular as in the 1950s? Perhaps they are restricted to niche applications?
  • Are they (in practice) always band-pass filters?

--catslash (talk) 23:39, 10 October 2010 (UTC)[reply]

  • ...does not exclude...piezoelectric... I don't see any pressing need to do this. Of course, quartz and ceramic filters work by producing acoustic waves through the piezoelectric effect and such waves amount to a mechanical motion in physics theory. However, they are not composed of an assembly of mechanical elements and are not generally described as mechanical filters. It is true that material on this class badly needs expanding on Wikipedia and I thought carefully about including them here, but they are really something quite different and there is a need to keep the article focused.
  • Have they been superseded... My assesment of the commercial position would be that their bread-and-butter base use in FDM telephony/telegraphy has collapsed due to the rise of digital technologies for mass transport of data. In other areas designers will try not to use the traditional mechanical "filter-in-a-can" unless absolutely unavoidable because of the expense (much as inductors are avoided in electronics). However, they can still be purchased and are particularly popular with amateur radio enthusiasts. The mechanical filter concept has been given a new lease of life with the rise of MEMS technology and the article already pretty much indicates this. I am not inclined to work on researching the commercial history, partly because what is already there is adequate and partly because of the awful reaction provoked by the addition of the section on trimming.
  • Are they (in practice) always band-pass... As an off-the-shelf telecomms or radio component, then probably yes, but any bandform is possible, witness the Norton design in the article which is low-pass. As a general statement, it could be said that a mechanical filter in a control system feedback path will generally be required to be low-pass.
  • SpinningSpark 14:21, 12 October 2010 (UTC)[reply]
Certainly the article should only cover filters consisting of a row of metal elements with a transducer at each end. There's clearly plenty to say about such assemblies, and the term mechanical filter is commonly used in this restricted sense (I believe). I didn't mean to suggest otherwise. I did mean to suggest that because the article strays beyond this meaning, the reader might wrongly suppose that it purported to fully address mechanical filters in a the widest sense (i.e. all those depending on mechanical vibration). Specific points:
  • In the lede the meaning of mechanical filter in this article is discussed, excluding filters without electrical ports, but nothing else.
  • The Sound reproduction sub-section may be highly relevant to the history, but is a very long digression into an area that has been explicitly excluded.
  • The third paragraph in the Resonators section briefly mentions all-piezoelectric designs, and this might give the impression that there was little more to say on this subject.
  • The MEMS filter section describes something which is quite a different beast.

So it would be nice to have a clearer statement of the intended scope of the article, plus a section that saying that in a wider sense, beyond this scope, there are other technologies (crystal filters, SAW, MEMS). Sorry that I did not see this at an earlier stage in the process. --catslash (talk) 21:18, 12 October 2010 (UTC)[reply]

Leaning to oppose - 1b, 2a, 2b concerns. I suspect the article may be mistitled, given the lead's lack of focus on the mechanical filter itself, its significance, and its reason for existing today alongside its electrical counterpart. This is further underlined by the reply above to that voiced concern: "The main point (perhaps even the essential point of this article) is that there is a great body of theory associated with electrical filters, and electrical networks in general. By transferrring all this theory into the mechanical domain it suddenly becomes possible to do all sorts of clever things with mechanical parts that would otherwise not have been possible, or at least, would have required parallel mechanical theories to be developed first." That may be the point of the article, but it is not stated in the lead to be the point of the mechanical filter. I also note that a whole section on trimming/adjustment has just been added, and another reviewer has now questioned the article's scope in respect of piezoelectric technologies. It gives me no pleasure to leave negative comments, particularly when an article exhibits generally good prose, but I suggest it may be necessary to take a step back and look again at the overall scope of the article. If the essential point of this article is as just quoted, then the title, lead and ToC should reflect that. PL290 (talk) 14:16, 11 October 2010 (UTC)[reply]

There's no reason that that the article should consider crystal filters or SAW filters, as these would probably be referred to as such, and not as mechanical filters. I was merely wondering whether when the scope of the article is discussed in the lede, it should be more clearly stated that only transducer-metal-transducer devices are considered (as opposed to any filter depending on mechanical vibrations). --catslash (talk) 15:22, 11 October 2010 (UTC)[reply]
  • I suspect the article may be mistitled... The article is about a component called mechanical filter. It is never called anything else. There is no other mechanical filter article on Wikipedia to disambiguate it from. What on earth is it supposed that the article might be expected to be called?
  • ...given the lead's lack of focus on the mechanical filter itself... In what way is this not focused on "mechanical filter itself"? The lede is entirely about the mechanical filter. I cannot fathom this unless it is referring to a previous comment about the lede including discussion of electrical filters. The relationship to electrical filters is an essential part of this article and is deeply embedded in the article structure. It would be preposterous to not have this in the lede: the lede is meant to be a summary of the article and this is most definitely in the article. The "Elements" and "Mechanical equivalent circuits" sections are about nothing else and the "Circuit designs" section repeatedly refers to the electrical equivalent circuit and several equivalent circuit diagrams are given.
  • ...its significance... Does not The high "quality factor", Q, that mechanical resonators can attain, far higher than that of an all-electrical LC circuit make it significantly different from other filter types?
...and its reason for existing today... I'm not sure that it needs to justify its existence in order to have a Wikipedia article, it merely needs to be notable. However, the reasons for its use are stated in the lede; applications requiring high-Q resonators - an example of which is stated to be good radio channel selectivity.
  • That may be the point of the article, but it is not stated in the lead to be the point of the mechanical filter. (in respect of the connection of the mechanical filter to electrical filter design). This comment is made after criticism of the article for focusing on the connection to electrical filters. It cannot be criticised for both failing to make the connection and for making it. The issue of transplanting theory from one domain where it is mature to another domain where it is not is important here and the lede does make this point. It used to refer to the Butterworth and Chebshev designs (common examples of mature and sophistacted designs in the electrical domain) being usable in the mechanical domain. This mention was criticised for the designs not previously being explained (well how could they be - this is the lede) and the specific designs have been removed. However the lede still says Electrical theory has developed a large library of mathematical forms that produce useful filter frequency responses and the mechanical filter designer is able to make direct use of these. which adequately makes the point.
  • I also note that a whole section on trimming/adjustment has just been added... This was added at the request of another reviewer and I now truly wish I had not bothered. it was not a trivial amount of effort to find an out-of-print book by one of the leading experts in the field, not available on Google except as snippets to get enough material for that section. It is hardly an essential part of the article, but it seemed to me that trimming of mechanical filters was notably more difficult to be worth inclusion so I made the effort. Previously, a request for more information on materials from a reviewer interested in that aspect resulted in a similar large, but ultimately non-essential, addition. I am reminded of a comment by J. R. R. Tolkein in reply to one of many requests for more background on Lord of the Rings:
...while many like you demand maps, others wish for geological indications rather than places; many want Elvish grammars, phonologies, and specimens; some want metrics and prosodies...Musicians want tunes, and music notation; archaeologists want ceramics and metallurgy; botanists want a more accurate description of the mallorn...historians want more details about the social and political structure...
Is Lord of the Rings any less of a masterpiece for not having included these things? Frankly, I found this comment so demotivating that I have not been able to reply to it for a couple of days. If the implication is that you are opposing because there might be something else "missing" then that is absurd. You are of course entitled to oppose, but to oppose on the grounds that the article is not comprehensive requires you to state what it is exactly that is missing, otherwise it is not an "actioanable objection" as the FAC page puts it.
  • another reviewer has now questioned the article's scope in respect of piezoelectric technologies No he has not as catslash made clear in his reply above, although I don't exactly go along with his definition of the scope as transducer-metal-transducer. My understanding of the scope is those filters which are composed of an assembly of mechanically connected parts each acting as an element of the filter analoguous to an electrical element. This does not exclude from the scope mechanical filters made from all-piezoelectric resonators. These are mentioned but as the article states, they are not favoured over metal alloys. To be honest I am not particularly knowledgable of quartz filters, but my understanding is that they are interconnected electrically, often in a lattice circuit or some equivalent. So while each quartz (or other piezo material) crystal vibrates acoustically and can therefore be described as a mechanical resonator, the filter as a whole is not manufactured as a mechanical machine with one part transferring motion to others. This puts it decidedly out of scope by definition, by the normal names for these parts, and by its means of manufacture being so different. MEMS devices on the other hand are specifically an assembly of mechanical parts and so are definitely within scope of the article, as well as being needed to bring the narrative of the article up-to-date.
  • SpinningSpark 18:11, 15 October 2010 (UTC)[reply]
The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.
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