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PCB-Ideas?

Discussion in 'Circuit Simulation & PCB Design' started by John Murdock, Feb 25, 2016.

  1. AnalogKid

    AnalogKid Well-Known Member

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    Creating a new part from scratch can be intimidating, and you are left with the nagging suspicion that you forgot something. OTOH, editing another part that already works perfectly is a much more safe path. When starting out, editing the doors off of a copied known-good part to turn it into something else is easier, safer, and faster than learning the ins and outs of the lib requirements.

    ak
     
    • Informative Informative x 1
  2. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    You're very welcome, I'm glad to hear of your success! :)
     
  3. John Murdock

    John Murdock Member

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    Does anyone know what this 3 digit LEd display would be listed as on Cadsoft eagle or if it is even on it.
    upload_2016-3-5_21-50-1.png
     
  4. dave

    Dave New Member

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  5. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Why not just use three 1-digit displays? You can multiplex them by connecting all of their control pins in parallel and using transistors on their common (cathode for CC or anode for CA) pins.
     
  6. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Can you provide the actual part number and link to the datasheet, if it is not a common device?

    John
     
  7. John Murdock

    John Murdock Member

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    [​IMG]
    Something like this?
     
  8. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Yes, exactly, though the configuration will vary depending on whether you are using common-anode or common-cathode displays. Also, that schematic is missing something. It looks like the displays are common-cathode, in which case the wire connecting to the emitters of the four transistors should be connected to ground. Common anode displays will have the collectors of the transistors connected to Vcc and the emitters connected to each of the common anodes of the displays.
     
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  9. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    IMO they are normally shown as individual digits, only when something like the Varitronics VIM-332 that has 7 segment digits in one contained unit would show as one module.
    Max.
     
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  10. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    Dirty Boards PCB mailed fast but took over a month in shipping, but the results look very good.
    Will know more at the test phase.
    Max.
     
  11. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Shame, they promised rubbish PCB's, typical a Chinese company dosnt deliver on its promise. I wont be ordering from them, if I order and pay for rubbish PCB's then thats what I expect, I dont expect to be fobbed off with good ones :D
     
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  12. spec

    spec Well-Known Member Most Helpful Member

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    Hy John,

    The component library that comes with EAGLE is a complete mess which makes it difficult to find parts. Farnell Element 14 have a load of updated libraries for EAGLE (you have to sign up) and CadSoft have a user group where you can download component libraries. Also there are EAGLE library parts all over the net- an advantage of using the 'industry standard' home/student/small business ECAD package..

    Two tips: you should be running EAGLE 7.5.2 as EAGLE 7.5.0 has a problem in that project sheets keep locking as your projects get bigger/more complex. You need to download and install EAGLE Beta 7.5.2 if you haven't already.

    The other tip is to set the grid to 0.05 inches rather than the default 0.1 inches (don't use a metric grid or you will cause problems).

    spec
     
    Last edited: Apr 8, 2016
  13. John Murdock

    John Murdock Member

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    That will come in handy for future reference thank you very much.
     
  14. spec

    spec Well-Known Member Most Helpful Member

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    No probs John- have fun. EAGLE is dead easy to use. :cool:

    spec
     
  15. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Go on rub it in!! I find it utterly impossible to get my head around the library system :D
     
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  16. spec

    spec Well-Known Member Most Helpful Member

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    If you think EAGLE libraries are difficult, have a go at Protel99. :eek:
    (if you don't already know, the big secret is to 'Use' the whole library every time you start a new project sheet. That way you don't have to do any messing about to place any component, but it does make your projects larger, particularly when backing up.)

    spec
     
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  17. John Murdock

    John Murdock Member

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    100% agree with that
     
  18. spec

    spec Well-Known Member Most Helpful Member

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    Is the problem finding a particular component, or is the problem placing any component? If it is the latter there is a simple solution.

    spec
     
  19. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Finding a component is my problem, i resorted to looking under the table in the end and still couldnt find any :D
     
  20. Dr_Doggy

    Dr_Doggy Well-Known Member

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    I just match the pin headers, who cares if my 3pin led is replaced with transistor, i dont simulate it, and my circuits are simple enough, or would make a note, or rename to custom part, so i dont forget later on
     
  21. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    I would suggest you review your design to review any input where glitches or contact bounce will affect your results. Also you cannot leave any CMOS input floating. (e.g. reset)

    Ensure your V+ will not over drive the chip since you have neglected the colour of the LED and the series current limiter, thus V+ will affect I_segment and driver heat.

    The other thing John is the Digit positions on the "logic diagram" should be logical, not scattered right to left. Bus lines can always be grouped if you label all the end points, such as segment letters.
     

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