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Electronics Forum / Basics / October 2006why do we use these
what is the use of composite signal generator, zero crossing detector and comparator > what is the use of composite signal generator, zero crossing detector > and comparator How long is a piece of string ? Perhaps you'd like to put these in some context ? Graham >what is the use of composite signal generator, zero crossing detector >and comparator --- Examples of devices called out in homework questions?  SignatureJohn Fields Professional Circuit Designer >>what is the use of composite signal generator, zero crossing detector >>and comparator > > --- > Examples of devices called out in homework questions? I believe that is the correct answer, since I was thinking of posting an almost identical reply. Michael >>>what is the use of composite signal generator, zero crossing detector >>>and comparator [quoted text clipped - 6 lines] > > Michael but this is a "basics" NG >but this is a "basics" NG It is obviously a homework assignment. The answers are readily available--probably in the OP's textbook. Perhaps you should consider changing to the *Teach a man to fish* school of thought. http://www.justfuckinggoogleit.com/search.pl?q=zero-crossing-detector > It is obviously a homework assignment. > The answers are readily available--probably in the OP's textbook. ======================================================= All you old dinosaurs over 50 that use plain text and newsgroups: The answer was indeed in his textbook. The internet is undoubtedly his primary textbook. Doesnt he get any points for seeking the counsel of the silverbacks on S.E.B.? >Doesnt he get any points >for seeking the counsel of the silverbacks on S.E.B.? The same credit he would get if he tried to copy the answers off someone else's exam or sat on his a.s and tried to get someone else to do his assigned tasks. The former would get him a zero --with other consequences likely, possibly expulsion-- and the latter would get him fired. >> It is obviously a homework assignment. >> The answers are readily available--probably in the OP's textbook. [quoted text clipped - 3 lines] > primary textbook. Doesnt he get any points for seeking the counsel of > the silverbacks on S.E.B.? Of course not. The point of pretty much all college education is not simply to come up with the right answers, but to teach the student how to get those answers ON THEIR OWN - whether that involves running the calculations yourself, or simply knowing what references to turn to. But other people don't fall into the category of acceptable other references - because I can guarantee you that once this person (with luck) graduates and tries to start work as an engineer or technician, turning to the person next to you and asking "would you solve this problem for me?" isn't going to cut it. It doesn't matter whether the "text" you need to look in is a book, the Net, or carved stone tablets; the point is that YOU yourself are supposed to be learning how to dig this stuff up when you need it. It's perfectly fine to ask the sort of questions that are going to lead to a better understanding of a given point - but it's not OK to ask what is obviously the equivalent of "would you fill in this blank for me?" Bob M. > what is the use of composite signal generator, zero crossing detector > and comparator 1. Composite signal generators are used in those applications where all-metal ones would be too heavy. 2. Zero crossing detectors are used when it is important to recognize and/or count the number of zeroes which cross one's path. In many cultures, having your path crossed by a zero is analogous to our beliefs regarding a black cat crossing your path. 3. "Comparator" is a term which derives from the same Latin root as the word "compose," i.e., it is a device which puts stuff together, as opposed to a "separator," which of course takes stuff apart. Best of luck on the homework! Bob M. >>what is the use of composite signal generator, zero crossing detector >>and comparator > > 1. Composite signal generators are used in those applications > where all-metal ones would be too heavy. > 2. Zero crossing detectors are used when it is important to > recognize and/or count the number of zeroes which cross > one's path. In many cultures, having your path crossed by a > zero is analogous to our beliefs regarding a black cat crossing > your path. This is important in some areas because zeroes are slippery and can wiggle through where a one can not. The ones may get stuck in the bit grate, whereas the zeros can slither through. Counting these is important in defining the efficacy of a bit grate (measured, of course, in it's duty cycle). Cheers PeteS > 3. "Comparator" is a term which derives from the same Latin > root as the word "compose," i.e., it is a device which puts [quoted text clipped - 4 lines] > > Bob M. Bob Myers wrote: >>2. Zero crossing detectors are used when it is important to >>recognize and/or count the number of zeroes which cross >>one's path. In many cultures, having your path crossed by a >>zero is analogous to our beliefs regarding a black cat crossing > > your path. . >This is important in some areas because zeroes are slippery >and can wiggle through where a one can not. You guys slay me. 8-) These rate with some of my favorite respones to homework trolls: http://groups.google.com/group/sci.electronics.basics/browse_frm/thread/694a3740 c4b044c7/8f1c19da2687c23b?q=out-*-Fields+textbook+*-megohms http://groups.google.com/group/sci.electronics.design/browse_frm/thread/47dd00f4 b3f38b03/3f0e98a24cd0fb82?q=*-*-*-unwilling-to-do-*-homework-*-*+remember-*+try- posting-to-*-*-*+zz-zz+your-teacher-*-*-*+qq-qq+*-*-exist http://groups.google.com/group/comp.arch.embedded/browse_frm/thread/7b1e35b1260b 7460/9319c5e1d13776bf?q=what.are.the.rules.*.*.*.*.*.*+some.managers+Hire-engine ers-that-did-their-own-homework-in-college A previous one from Pete: http://groups.google.com/group/sci.electronics.basics/browse_frm/thread/8ed901ba 2717044a?q=*-job-function-*-*-*-*+*-*-english-*-*+*-platitudes-*+*-*-*-dangerous +*-*-what-you-really-mean+insert-task-here+*-having-to-think . . >>Best of luck on the homework! Now that the accounting industry has oversight, http://www.google.com/search?q=Arthur-Anderson+Enron+Sarbanes-Oxley it appears the lazy, corner-cutters are trying to find other fields. > Bob Myers wrote: > [quoted text clipped - 25 lines] > http://www.google.com/search?q=Arthur-Anderson+Enron+Sarbanes-Oxley > it appears the lazy, corner-cutters are trying to find other fields. I had been considering writing an authoritive guide on 'How to post your homework questions to s.e.b and s.e.d', but I never got past the first paragraph as I kept snorting my wine on the keyboard. Now there is the possibility I could write such a thing while not drinking wine, but that would remove any real point ;) Cheers PeteS > > Bob Myers wrote: > > [quoted text clipped - 36 lines] > > PeteS We need a real, nice "Homework helper FAQ" for the sci.electronics.* newsgroups. Maybe we could all use up lots of puns before they go stale? ;-) SignatureService to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida >>>Bob Myers wrote: >>> [quoted text clipped - 40 lines] > newsgroups. Maybe we could all use up lots of puns before they go > stale? ;-) I was thinking on the lines of a non-FAQ (mild sarcasm mode) thus: Title: The title of your question is all important. To get the attention of the people who can answer your question, you need to make it stand out. Known methods of doing this: 1. USE ALL CAPS 2. Reference a current political problem 3. Ensure it is indecipherably vague. 4. Use 733t 5p34k, or txt spk Examples: WHY DOES THIS IC RESET ALL THE TIME? Are Republicans to blame for my project? Confubulator fries? Cn U Hlp wth prblm? and so forth ;) and then perhaps a serious (well, mildly serious) one afterwards that gives real guidance. Make it through the first part and one is rewarded :) Cheers PeteS > >>>Bob Myers wrote: > >>> [quoted text clipped - 67 lines] > > PeteS Just make sure that they learn to ask, "Doyahal want fries with that?" ;-) SignatureService to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida >>>what is the use of composite signal generator, zero crossing detector >>>and comparator [quoted text clipped - 17 lines] > > PeteS This is, in fact how data compression is accomplished. Since ones are skinnier than zeros, you can install a bit grate in the data stream to trap the ones. Let the zeros pass through to oblivion and use the ones as the new data stream. ...jerry >>>> what is the use of composite signal generator, zero crossing detector >>>> and comparator [quoted text clipped - 23 lines] > > ...jerry You are evil. I am impressed. Cheers PeteS >what is the use of composite signal generator, zero crossing detector >and comparator http://groups.google.com/group/sci.electronics.basics/msg/e8b9dc477569c6db?q=usi ng-the-group-*-*-*-to-get-answers-to-homework-questions+*-*-*-*-*-*-explanation- of-why-most-people-won't-*-*-*+*-*-*-*-meant-to-reinforce-*-*-*-*-class+*-no-rea l-education-*-*-*+not.the.place+textbooks+context+reading >what is the use of composite signal generator, zero crossing detector >and comparator a zero crossing detect circuit is used to indicat when and AC voltage is crossing the 0V line or within a window of a few volts either way. You know that AC voltages swing to a positive voltage and then a negative and this repeats continuously right? If you are switch something on, at the point the current starts flowing, it can make "noise" both electrically and within the radio spectrum (you may have seen this as lines of interference on your TV when someone has gone past on a motorbike or similar - the Radio interference from the ignition circuit is temporarily swamping the TV signal and being displayed as rubbish on the screen). So, if you turn on an AC device, you generally don't have any idea where in the swing cycle the voltage is and if it is significantly in, current will "rush" in to the device - with the same effect as the motorbike. Dimmer switches on lighting that don't use resistors use a triac to switch to the voltage on and off rapidly - because the bulb take a while to reach full brightness, if you switch off the power before it gets there it will appear to be dim constantly, but if you do this without a zero crossing trigger of some sorts it will play merry hell with your electrics and TV. A zero crossing detect will tell when it's safe to switch the power on... because you are at zero voltage, there is no current flowing (actually there will be a bit because 0v lasts for a fraction of a second) so you allow the curretn to build up nicely with the voltage. You can turn the power off anywhere in the cycle with minimum interference. So to recap, ZCD lets you know (in this application) when to switch the power on to eliminate electrical and RF noise (also stops overheating) ---- A comparator lets you compare two voltages. One is usually a reference and the output of the comparator will be at 0v so long as the input voltage remains less than the reference. as soon as it is more, the output will go "high" (to the positive supply voltage). A window comparator will have two references and the output will go high only when the input voltage is in between those - you could make a ZCD out of a window comparator - if you set the lower reference to same -0.5v and the upper to +0.5v, the output would go high breifly for the time the imput voltage was between these two levels (right around 0v) dhana wrote: >>what is the use of composite signal generator, zero crossing detector >>and comparator . >a zero crossing detect circuit is... When you subsidize a behavior, you get more of it. If the OP is too lazy to pay attention in class or to learn to use Google, a failing grade is apt. Please don't feed the homework trolls. >dhana wrote: >>>what is the use of composite signal generator, zero crossing detector [quoted text clipped - 7 lines] >a failing grade is apt. >Please don't feed the homework trolls. I hear what you are saying Jeff, and while I do agree that this is probably someones homework I chose to give the benefit of the doubt. Certainly if this had been posted anywhere but SEB I would have ignored it. I'll try to be a bit more discerning in the future but I remember what a mystery it all was (and a lot still is) all those years ago - I couldn't even find someone to tell me how the pins on a transistor related to the connections inside the circle (which was the emitter) ! so much water under the bridge since then :o) >>dhana wrote: >> [quoted text clipped - 21 lines] > related to the connections inside the circle (which was the emitter) ! > so much water under the bridge since then :o) I think what JeffM (and myself) are saying is we help those who have tried to help themselves :) I will definitely help with homework *provided the OP has tried to solve the problem already* and is perhaps stuck on phraseologu or perhaps a somewhat murky chapter in a text. To paraphrase, _We help those who help themselves_ Cheers PeteS > >>dhana wrote: > >> [quoted text clipped - 30 lines] > > To paraphrase, _We help those who help themselves_ All the others are to proceed to the closest fast food place to apply for their job in their lifelong career in the food service industry. ;-) SignatureService to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida >>>>dhana wrote: >>>> [quoted text clipped - 36 lines] > > Snort I know we all agree, but many an OP doesn't seem to realise that if you don't do your own work, you really won't learn anything. There are some professions where this may, in fact, be desirable. Engineering (especially design engineering) isn't one of them ;) Cheers PeteS > >>>>dhana wrote: > >>>> [quoted text clipped - 45 lines] > > PeteS I had no one to answer my questions when I was eight years old, so I read every book I could find, including college textbooks. I was working part time in a TV shop at 13, and I still do my best to keep up, 40+ years later. SignatureService to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida > I was working part time in a TV shop at 13, and I still do my best to keep up, > 40+ years later. ==================================== So Mike... I guess you are the neighborhood electronics fixit guy... folks bring their radios over to have the tubes checked and the IF tweaked? Have a workshop with a scope and signal generator and stuff? > > I was working part time in a TV shop at 13, and I still do my best to keep up, > > 40+ years later. > ==================================== > So Mike... I guess you are the neighborhood electronics fixit guy... > folks bring their radios over to have the tubes checked and the IF > tweaked? Have a workshop with a scope and signal generator and stuff? Not anymore. At my last job I worked on $80,000 (US) telemetry receivers as an engineering tech. I never "tweaked" IFs. I bought a signal generator and VTVM back in the '60s to do proper alignment, when needed. I repaired Commercial two way radios at one time, and I was a broadcast engineer in both Radio and TV (WACX, 5 MW EIRP, 1749 foot tower) Most of my test equipment was destroyed during the hurricanes a couple years ago, and I still need to replace the roof on both shop buildings before I even consider setting up a couple full benches, again. The benches are covered in plastic, and unusable right now. I am 100% disabled now, and can only stand a couple hours a day, which makes a lot of what I want to do impossible. I spend my time repairing computers and giving them away, to try to stay busy. SignatureService to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida > what is the use of composite signal generator, zero crossing detector > and comparator A composite signal generator generates a composite signal. A zero crossing detector detects a zero-crossing at its input. A comparator compares two signals. Hope This Helps! Rich |
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