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Schematics: Drawing ICs and Voltage Regulators.

  1. Sep 6, 2011 #1
    I'm working with an instructor at the local community college to fix a bug in my first project, but he asked me to give him a schematic to look over before we meet in person. I know what resistors and the other simple stuff looks like, but I don't know the symbol for ICs and VRs.

    Since the symbol for ICs are dependent to each individual IC, do I just draw a box and label the pins I'm using? That seems the most intuitive, to me.

    I have no idea what to do for the VR. Can someone upload a pic or something? It would be immensely appreciated.
  2. jcsd
  3. Sep 7, 2011 #2
    Use WWW.
    Locate the manufacture of the part you are using and use the same symbol the manufacture uses.
  4. Sep 7, 2011 #3


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    I usually just create my own part in a custom library--just use a box with connections. For instance:

    They made the fancy DIP package and followed the pinout, but this is not necessary. For instance:

    Make sure you use the IC number, and some annotation (e.g. voltage regulator, shift register) frequently goes a long way towards making your schematic readable. Speaking of readability, try to minimize clutter, and keep things neat!
  5. Sep 8, 2011 #4
  6. Sep 8, 2011 #5
    Okay, I get how to label an IC, but what about the VR? Is there a symbol for it, or for I just label it with a VR and label the pins?

    Thanks for all the help about the ICs.
  7. Sep 8, 2011 #6


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    Just treat it the same way as your ICs.

    Generally, I make it so the input and output are left and right (you can usually mirror to invert directions), and then a ground terminal pointing downwards. Assuming this is a three-terminal voltage regulator. If you need feedback (e.g. for an LM1084-ADJ), you just put your feedback circuitry around it.
  8. Sep 8, 2011 #7


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    Usually in the datasheet for the voltage regulator, they will show some application circuits at the end. You can just use the same symbol that they use in their application circuits.
  9. Sep 8, 2011 #8
    Okay, that makes sense. I'm gonna draw it on a piece of paper. I'll post a pic when I'm done.

    Thanks again.
  10. Sep 8, 2011 #9
    How's this? Can you read it?

    Attached Files:

    • IMG.jpg
      File size:
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  11. Sep 9, 2011 #10
    I've been on the sending and receiving end of schematics, and there are a few basic rules that I find helpful (almost essential at my age). They are:

    Ground symbols and negative power supplies point downwards
    Positive power supply terminals point upwards
    Incoming signals flow in from the left and have a destination note if leaving the page
    Outgoing signals exit to the right and have a destination note if leaving the page
    Simple devices, like regulators, are best presented simular to the actual pin orientations.
    Pin numbers are essential
    Complex devices or devices that tend to get lost in circuitry are better drawn with an extra "gate" that represents where they are connected to power pins. Which devices? logic gates, op amps, large chips.
    Finally, Some devices require power supply "maintenance" close to the chip or module. This is typically in the form of capacitors, but may include ferrite beads, resistors, or inductors. Keep these items close to the associated component such that their function is more apparent.

    Best Wishes,

  12. Sep 9, 2011 #11


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    Agree with your comments, Mike in plano :)

    whereever possible ALWAYS point GND (grounds) down

    here's the standard for a 3 term regulator you put in the appropriate part # in the box :)



    Attached Files:

  13. Sep 9, 2011 #12
    Okay, I messed up the ground symbols and the positive charge isn't pointing up, but other than that, do I effectively get my idea across. I'm okay with seeming novice; I am novice. :) I'm only worried about effectiveness. The rest will come with experience and education, should I decide to pursue a career or hobby in EE.

    Thanks for the invaluable tips, Mike. There's a lot to be learned from experienced people like yourself, that can't be learned from reading datasheets and tutorials. That's one of the reasons I reached out the local CC professor; I happen to know, from meeting him, that he's a very experienced and knowledgeable person.
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