Understanding Schematics

Discussion in 'The Projects Forum' started by rhenxoff1, Oct 16, 2014.

  1. rhenxoff1

    Thread Starter New Member

    Jan 25, 2014
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    Dear sir, when i unfold an electronic diagram i am afraid at see many symbols and lines crossing the area in all directions. A few moments after i could identify the components and which lines are connected and which not.
    But i still don´t understand the schematic.
    If i could split the diagram into small building blocks and see the connections between the other building blocks maybe i could know how the circuit will work in the real live.
    I appreciate any tips, advice or address to tutorials where i can find any techniques about how read and understand the working of a electronic circuit showed in a diagram.
    I apologize for my English.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    dots are connections
    crossovers without dots usually are not
    ground symbols just mean connect all of them together
    nodes/wires with same names, connect together
    Symbols here
     
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  3. #12

    Expert

    Nov 30, 2010
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    You can re-draw subsections to make them seem simpler, but schematics are a language that is as valid as French or German or English. You develop a vocabulary over months and years. You develop an understanding of each component, its needs, and its limitations. You learn subsections that become as common as the word, "the".

    Eventually, you will read schematics faster than you can read your original spoken language. The important word here is, "eventually". Nobody is born knowing a language and nobody learns a second language in ten minutes or ten days. If electronics is in your blood, you will know these things in due time, with one exception: You never stop learning.
     
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  4. MikeML

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  5. JDT

    Well-Known Member

    Feb 12, 2009
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    Of course, it all depends on how well the diagram is drawn.

    A circuit diagram should show how it works. Not where everything actually is.

    Ideally, positive at the top, negative at the bottom. Signal flow from left to right. Not always possible I know.

    A classic example of a bad circuit diagram used to be the electrical diagram of a car. The diagram had to have the headlamps at one side of the page, tail lamps at the other and multiple "railway lines" of wires in between. Impossible to follow.

    Car diagrams seem to have improved in recent years.

    Edit:
    Actually, the London tube map was originally drawn by an electrical engineer. Now copied by transport authorities all over the world. The big difference was that the stations were not drawn in their correct positions but the lines were straight or angled and coloured.
     
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  6. #12

    Expert

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    I read about that. If drawn to scale as a physical representation, it is nearly impossible to read.
    So it was decided to make the map readable and to H311 with physical accuracy.

    Reference: The scar on Professor Dumbledore's left knee. :D
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You will also come across two methods of showing connections, one is where a conductor or line crosses another you will see a small semi circle at the crossing indicating no connection and if there is no semi circle a connection is made.
    Not to be confused with the second method (which is more common and I favour) where a connection is indicated by a dot, and if the conductor crosses without dot, there is no connection.
    Also there are N.A. logic symbols such as JIC and DIN in Europe, which can add confusion.
    Look up one of the many circuit sites and you should soon get a feel for diagram layout.
    e.g.
    http://www.satsleuth.com/schematics.htm
    http://www.repairfaq.org/sam/samschem.htm
     
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  8. Nykolas

    Member

    Aug 27, 2013
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    The article in post 4 is quite good. Unfortunately in Fig. #3 in the centre schematic they show C1, R1, R2 connected to the base of Q1 in a X-point. That is a no-no. Only draw T-type connections, not X.
    The other thing, as we do not know the OPs location, is what drawing symbols are used there. DIN standard schematic symbols are often quite different (and more informative, used properly) than ANSIs.. E
     
  9. rhenxoff1

    Thread Starter New Member

    Jan 25, 2014
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    Really the less important for me is identify if two wires are connect or not. I focus better on the interpretation of the schematics. -I visit the links you suggest and are very good and adequate for me. However i would like to know if there are a some techniques to dissect a diagram and based on the findings in this task, one could explain how the circuit will work in the real live and why it operates in that way. Maybe my fail in the English language make me some confuse.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The other problem is that the description 'Schematics' can cover many forms of Electrical and Electronic formats apart from DIN or ANSI format, the main thing is to learn the individual function of each individual type of logic block.
    is really a question of first learning how each individual component in a circuit function, this information is gleaned from the manufacturers specification sheets.
    Only then can you tie each component in a circuit together and understand the overall circuit function.
    Max.
     
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  11. rhenxoff1

    Thread Starter New Member

    Jan 25, 2014
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    Well Max, you touch a good point "the building blocks". Where can i find the explanation of the function of each one of them and how them works. I recap: first, what is the function of one building block? and second, how each building block works?. The idea is track the main signal from the input of first block and then the output to be transfer to the following block until leave the total circuit.
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If I were to come across a circuit that had components I was not familiar with I would first obtain the manuf spec sheet and examine that, circuits as a rule flow from left to right in N.A., you may come across European practice where the flow is from top to bottom.
    If you start with simple standard TTL or CMOS IC circuits for e.g., then in general all spec sheets can be found from different suppliers sites, they usually give a detailed description and/or logic diagram of the function of the IC.
    From this you can build on your knowledge, it is only by gradually studying each that experience is gained.
    Concurrently you can also study transistor and Fet discrete components as you will surely come across these also.
    The AAC Lessons are also a good place to find explanation of how discrete components and circuits work.
    Max.
     
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