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Electronic circuits work in mysterious ways?

Discussion in 'General Electronics Discussion' started by emanski, Apr 9, 2018.

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  1. emanski

    emanski

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    Mar 6, 2018
    As a new hobbiest trying to understand an astable multivibrator/flipflop I have studied three explanations of how they work and no two were the same! I also found two schematics that used the same components but were connected/wired differently. I bread boarded them and they both worked. Does anyone really know how electronic circuits work or is It that thru trial and error it has been discovered that when electronic components are wired in a particular way "this" is what happens. I'm tempted to give up on electronics and stick with mechanical contrivances. At least with things mechanical one can see how they work. Any comments?
     
  2. Minder

    Minder

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    Apr 24, 2015
    davenn likes this.
  3. @xi@g@me

    @[email protected]@me

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    Dec 15, 2016
    We discovered new components and new ways of using them with experiments of course, but this kind of circuit is now well known and has a clear explanation. I'm sorry but I can not tell you more because it's still a bit dark for me, but the best way would be to understand the components well and experiment yourself. You can for example breadboard one of the schematics, try to explain how it should work and what values you should read on various places of the circuit, and then use your multimeter to read the values. If they do not correspond to what you calculated, than you can change your theory and try again :)
    Electronics are hard at the beginning (especially about transistors for me), and experimenting / breadboarding it the best way to make it good I guess.
    You'll make it, I'm sure of that :)
     
  4. BobK

    BobK

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    Jan 5, 2010
    No, they work in quite predictable ways when designed properly.

    Get LTSPICE, it is free, and you can examine the behavior of circuits in detail, which might help you understand them better.

    Bob
     
  5. Cannonball

    Cannonball

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    May 6, 2017
    Don't give up. The more you learn the more fun you have.

    Go to the library and check out books on basic electronics. Do a google search on basic electronics and read and study everything you find on basic electronics.

    You will find disagreements even among the experts. Don't let that discourage you.

    If I can help in any way my email address is [email protected]. Keep on studying and build the basic circuits on a breadboard and study them.
     
    OBW0549 likes this.
  6. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Yes.

    Throughout the 1700's and 1800's, all of the math for electricity and electronics was discovered, worked out, tuned up, etc., all before the invention of the vacuum tube. In the 1890's, Oliver Heavyside overhauled Maxwell's field equations into the form we know today, and that was it for the basics. And BTW, Edison's researchers had the basics of a vacuum tube in the 1880's, but Tommy boy wasn't smart enough to realize what he had, so the "Edison Effect" lay dormant for 21 years.

    Since then, other active components like transistors and IC's have come along, but the basic operational concepts of most circuits have not changed for many decades. Depending on the circuit there can be multiple ways to construct it, and for each construction there can be multiple ways to describe or explain it. Those variations are evidence of creativity and imagination, not a lack of understanding. OK, for explanations on the internet, 50% really are a lack of understanding.

    https://en.wikipedia.org/wiki/Multivibrator#History

    ak
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Electronic circuits are designed in a methodical process the same way as a book is written by an author: Not by putting together components (or words) and examining the outcome, but by careful planning of the structire of the circuit (book) and careful selection and combination of the components (words).

    You may find different explanations for a circuit's behavior all of which may be correct (incidentally don't wonder if you stumble over an incorrect one). Somethimes the explanation depends on how you look at a circuit or a phenomenon. HOhm's law is a very basic example. You can express it as:
    1. V = I*R
    2. I = V/R
    3. R = V/I
    These 3 equations are equivalent, but one could explain the bahvior as:
    1. A voltage V develops across a resistance R in direct proportion to the current I.
    2. A currrent I flows through a resistance R if a voltage V is applied.
    3. The resistance of a component is derived by dividing the voltage across it by the current through it.
    Similar reasoning may be applied to more complex circuits, as the multivibrator in your case.
    Note also that as the saying goes "many roads lead to Rome" so many different implementations (circuits) may lead to the same outcome. You'll be able to locate (I guess) a dozen or more different circuits called astable multivibrator.
     
  8. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    "Things mechanical" can be extremely complicated and difficult to visualize "how they work." And without a background mathematical foundation in mechanics, including strength of materials, new designs economically produced are virtually impossible. In recent years, 3D modeling software has aided visualization, but only after the fact: you still have to create the model. I personally have difficulty with "seeing" how multi-lobed, smooth surface machined, interacting moving parts actually work, even with an operating physical example in front of me. Can you visualize a "geared" mechanism that has no teeth, only smoothly meshed lobes moving in three dimensional paths? Even something as "simple" as a differential planetary gear transmission is a mystery to me... I wouldn't even begin to know how to "design" one from specs, although I do feel somewhat competent in selecting one from a catalog of available designs, based on speed and torque requirements.

    Electronics may seem to be all about "trial and error" but it is not. You need a firm foundation in physics and math to even begin to really understand electronics. And it helps to further spread your knowledge into other scientific fields to better "visualize" what electronics applications are possible, now and in the future. Electronics is no longer just about radios and television sets as it was in the 1940s.

    I grew up at the end of an era when all electronics were based on vacuum tubes. Making the transition to solid-state electronics in the 1950s and 1960s was difficult for many people skilled at vacuum tube electronics, but especially difficult for those lacking the math and physics background necessary for any real understanding of "how it works." I was a member of the crew on that boat, having "played" with electricity and tube-circuit electronics from a very early age. I was still a teenager "electronics hobbyist" when it first became economically possible to begin "playing" with transistor circuits. But "play" is all it was: "monkey see, monkey do" type of activity with no real understanding of design principles. Lots of fun, but hardly anything to base a career on. That came much later with a formal education and a four-year tour of military service that exposed me to real electronics design, as well as real mechanical design. Ever hear of a swash-plate hydraulic drive motor? Needless to say, I was "hooked" on electronics for the rest of my life.

    I don't want to down-play the benefit of "hands on" experimentation to learn electronics. I have known "engineers" with lots of formal education who couldn't design their way out of a paper bag because they had no experience with real circuits. But experience alone is of little value. Electronics is a science, and all science is based on observation and experiment... the so-called scientific method. You first observe something, then you form an hypothesis in an attempt to explain what you observed.

    The next step is extremely important: you use your hypothesis to predict how something similar will behave and create an experiment to test that hypothesis. The results of the experiment will either confirm or deny the hypothesis, but experiment never proves the validity of any hypothesis. What experiment can do is prove a hypothesis to be wrong, or to paraphrase Thomas Edison, "We have found yet another way that doesn't work. Back to work to find a way that does."

    If an experiment seems to confirm an hypothesis, it needs to be repeated by others and produce the same results (within the limits of measurement error) over a sufficient period of time (sometimes decades) before the hypothesis can be generally accepted as true. Even so, just one counter-example experiment is sufficient to render an hypothesis invalid, or at least insufficient to explain what is really going on.

    So, as you begin to learn electronics, do experiment. Learn from the work of others who preceded you down this wondrous, branching path. Learn some math... arithmetic, algebra, trigonometry, geometry, calculus, differential equations, linear algebras... yada, yada, yada... as much math as your brain can absorb without melting. Learn some physics... learn a LOT of physics, at least to the undergraduate level. No need to learn how to fission stuff in your kitchen, but learn some chemistry too. And maybe throw in some stuff from mechanical and civil engineering to round out your education and prepare for some real-world electronic design.

    If I were younger, and knew then what I know now, I would have added biological sciences to my education curriculum. There are huge applications for electronics to be performed by those who can communicate with biologists, physicians, and healthcare providers, to name just a few. I am alive today because of an implanted heart pacemaker/defibrillator. This gadget may have been speced out by a medical doctor, but I am sure it was designed and built by electrical engineers... and NOT by trial and error.
     
  9. OBW0549

    OBW0549

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    Jul 5, 2016
    No, trial and error had little or nothing to do with the development of these circuits; they were created through a deliberate process by people who understood the components, their properties, and the mathematics involved in describing their operation. Most of that knowledge has been around since long before any of us were born.

    The only reason these circuits seem mysterious to you is that you're new to electronics and haven't yet learned the basics; once you have, they'll become understandable.

    Don't restrict yourself to tinkering with circuits you find on the Internet; get some good electronics textbooks and start learning how this stuff works.
     
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