Cannot find Vcc and Gnd on eagle

Discussion in 'General Electronics Chat' started by nathomas, May 2, 2011.

  1. nathomas

    Thread Starter Member

    Mar 3, 2011
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    I am using Eagle for the first time and I cannot find the Vcc and Gnd pins for both the Lm339 and 4001 ICs. I have attached a pic of the schematic.
     
  2. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Eagle sometimes does not include the power pins, as they are implied. It assumes you already know what pins go to (+) and to (-).
     
  3. nathomas

    Thread Starter Member

    Mar 3, 2011
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    So when I do the routing on the board I have to route them accordingly? So what is the advantage of doing the routing on the schematic?
     
  4. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    Here is an EAGLE tutorial: http://fab.cba.mit.edu/classes/MIT/863.07/people/stephen/tutorial-eng.pdf

    Here is a small portion from the tutorial on POWER and GROUND connections of the components...

    "EAGLE, by default, assumes that all active components will be attached to the same power source and ground. The power pins are therefore not shown, and are automatically connected to the Power Source and Ground when generating a board (unless the user connects them to other signals). Use the INVOKE command in case you want to place it in the schematic.

    Most of the EAGLE library devices, which have only one VCC and one GND
    pin, are defined so that the power pins, by default, are not visible. In some cases it makes sense to make the power pins in an IC visible, as in the 555N stored in the linear library. In such a case connect the power pins with the appropriate nets."

    I don't know what version EAGLE is on now but it may still be similar to this earlier document.
     
  5. nathomas

    Thread Starter Member

    Mar 3, 2011
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    I am gettin this error when I attach the vcc and gnd pins of the ICs to +12 and Gnd in my circuit. please see attached.
     
  6. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    It is probably because you have your capacitor backwards--You have the (+) side connected to -12V.
     
  7. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    Let me start by saying, I haven't used EAGLE in a long time. The symbols you are using for your supplies look to me like an "off page" type of connection. If you change it to a true supply type connection, which can be a small triangle or single arrow, you might not get the error. I don't have EAGLE on this machine so I can not direct you to the different symbols more specifically.

    Also, do not connect the outputs of the unused comparators and logic gates to ground.
     
  8. nathomas

    Thread Starter Member

    Mar 3, 2011
    82
    0
    could anyone give me the basics of routing the board manually. what do i have to look out for and what are the normal industry standards. my board is pretty standard. Could anyone help me with how many layers i would need. there is only one channel i would need AC 220V passing though at the relay connection. so what kind of channels should I use. and what about vias? I am gettin an error as shown below while using the auto route feature.
    thanks in advance.
     
  9. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    Here is a calculator to advise on track widths and clearances between tracks for required voltages and currents of your design.
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    Hmmm, I regularly place the unused comparators outputs to ground, it does nice things to the board layout. A LM393 can have pins 1,2,3, and 4 all grounded with no problem. Eagle will not allow this?
     
  11. nathomas

    Thread Starter Member

    Mar 3, 2011
    82
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    I did not get the link for that calculator you mentioned. thanks in advance.
     
  12. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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  13. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
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    Sorry Bill,

    When I first looked at the schematic and wrote the reply I assumed they were opamps. I made the comparator change at the last second without thinking about the open collector outputs...
     
    Wendy likes this.
  14. nathomas

    Thread Starter Member

    Mar 3, 2011
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    i used another vcc and gnd and it worked. thanks StayatHomeElectronics.
     
  15. nathomas

    Thread Starter Member

    Mar 3, 2011
    82
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    I still have trouble with this LED overlap error. could anybody tell me what is the problem.
     
  16. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    Try moving the LED to see if there is a small piece of track or via or something in the area.

    Can you zoom into the area where the problem is and show another picture? Post picture after you try moving the LED...
     
  17. nathomas

    Thread Starter Member

    Mar 3, 2011
    82
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    This is how it is with the led moved. thanks for looking.
     
    • led2.png
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  18. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    Does it still give you the error?

    It looks like there are two "keep out" areas on the board. Are those supposed to be there?
     
  19. nathomas

    Thread Starter Member

    Mar 3, 2011
    82
    0
    It is still showing the errors. I do not know about the keep out areas. how do i find out about those. plus there is no connection between the led and anything on the board. the autoroute did not connect the led to anything. any idea why?
     
  20. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    What is the LED part that you placed in the schematic? I'll see if I can look at it here.

    Can you delete the items left behind when you moved the LEDs?

    The autorouter probably didn't connect to the LEDs as a result of the error.

    Another thing to try: change out the LED part in the schematic and resync it to the PCB. See if the error is still there...
     
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