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EAGLE User Chat (English) Preferred power supply connections?
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Related

Preferred power supply connections?

Former Member
Former Member over 15 years ago

The schematic I am "capturing" are based on public domain circuits for

audio processing modules in a modular analog synthesizer. There are some

standard power connection schemes which I intend to follow consisting of

+/- 15 Vdc and ground. Typically, the +/- supplies go through a ferrite

bead and a couple of filtering capacitors before hitting the PCB's power

nets.

 

What is the best way to make a power net for the PCB components bcause it

is separated from the power input jack by the ferrite bead? If I connect

the connector pins to the supply +15 and -15 nets, I can't use them on the

PCB. So, what is the best net to use to PCB components to the other side of

the ferrite beads? Should use one of the other available supply nets or

make a unique power net?

 

I have played with different ways to do it, and they seem to work, but as

I'm new at this capture stuff, I'd like to know if there are standard or

preferred ways to accomplish this.

 

This image kind of shows what I mean.

 

Thanks

David

 

 

 

--

Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

 

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  • autodeskguest
    autodeskguest over 15 years ago

    dingebre wrote on Wed, 24 February 2010 21:57

    This image kind of shows what I mean.

     

    No, it shows a mess.  There is rotated text all over the place, labels

    overlapping other labels and parts, and missing values.  If you don't care

    about your design, there is no reason I should either.

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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  • Former Member
    Former Member over 15 years ago

     

    "Olin Lathrop" <eagle@embedinc.com> wrote in message

    news:hm60oi$830$1@cheetah.cadsoft.de...

    dingebre wrote on Wed, 24 February 2010 21:57

    This image kind of shows what I mean.

     

    No, it shows a mess.  There is rotated text all over the place, labels

    overlapping other labels and parts, and missing values.  If you don't care

    about your design, there is no reason I should either.

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

    Olin,

     

    This kind of response is completely inappropriate.  If you don't care then

    don't bother responding.  Why even waste your time?

     

    Unbelievable.

     

    Terri

     

     

     

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  • Former Member
    Former Member over 15 years ago

    Olin wrote on Thu, 25 February 2010 07:16

    dingebre wrote on Wed, 24 February 2010 21:57

    This image kind of shows what I mean.

     

    No, it shows a mess.  There is rotated text all over the place, labels

    overlapping other labels and parts, and missing values.  If you don't

    care about your design, there is no reason I should either.

     

     

    Hi Olin, you're reading too much into the "design". This is not a real

    schematic.

     

    I'm only illustrating the power connections. I am showing the +/-15 volts

    to the plug, and one way I was thinking to do the other power nets. I don't

    even know if this design is electrically "real" image

     

    I only ask a little patience. I'm very new to using Eagle and want to learn

    good habits. Would you maybe take a second look? I'd like some advice about

    how to handle the power nets on the "real" circuits I'd like to work on.

     

    Should I do it kind of like in that illustration? Use the supply library

    +/- 15 for the plug and then a generic supply symbol to connect the +/-

    supplies on the components? Or is there a better way?

     

    Thanks for looking Olin.

     

    David

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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  • autodeskguest
    autodeskguest over 15 years ago

    Terri Miller wrote on Thu, 25 February 2010 09:48

    "Olin Lathrop" <eagle@embedinc.com[/email]> wrote in message

    news:hm60oi$830$1@cheetah.cadsoft.de...[/email]

    dingebre wrote on Wed, 24 February 2010 21:57

    This image kind of shows what I mean.

     

    No, it shows a mess.  There is rotated text all over the place,

    labels

    overlapping other labels and parts, and missing values.  If you

    don't care

    about your design, there is no reason I should either.

    --

    Browser access to CadSoft Support Forums at

    http://www.eaglecentral.ca

     

    Olin,

     

    This kind of response is completely inappropriate.  If you don't care

    then

    don't bother responding.  Why even waste your time?

     

    Unbelievable.

     

     

    I agree Terry.  I've sent a PM to Olin about this.  You're not the only one

    to complain.

     

    James.

     

    --

    James Morrison  ~~~  Stratford Digital

     

    email:  james@eaglecentral.ca

    web: http://www.eaglecentral.ca

     

    Specializing in CadSoft EAGLE

    • Online Sales to North America

    • Electronic Design Services

    • EAGLE Enterprise Toolkit

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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  • autodeskguest
    autodeskguest over 15 years ago

    dingebre wrote on Wed, 24 February 2010 21:57

    The schematic I am "capturing" are based on public domain circuits for

    audio processing modules in a modular analog synthesizer. There are some

    standard power connection schemes which I intend to follow consisting of

    +/- 15 Vdc and ground. Typically, the +/- supplies go through a ferrite

    bead and a couple of filtering capacitors before hitting the PCB's power

    nets.

     

    What is the best way to make a power net for the PCB components bcause

    it is separated from the power input jack by the ferrite bead? If I

    connect the connector pins to the supply +15 and -15 nets, I can't use

    them on the PCB. So, what is the best net to use to PCB components to the

    other side of the ferrite beads? Should use one of the other available

    supply nets or make a unique power net?

     

    I have played with different ways to do it, and they seem to work, but

    as I'm new at this capture stuff, I'd like to know if there are standard

    or preferred ways to accomplish this.

     

    This image kind of shows what I mean.

     

     

    Hi David,

     

    There are a few ways to do it.  First, every signal name in EAGLE is

    global.  So if you simply name a net to a signal name it will be connected

    to any other net with the same name whether it looks like it or not.  So

    watch yourself there.

     

    So you have a pin connected to a ferrite that goes to a plane then you can

    do a few things:

     

    1)  name (and label) the net between the pin and the ferrite.  That can be

    helpful.

     

    2)  create a custom supply symbol that indicates  it's function.  This can

    work too and can help with readability if that net goes somewhere else

    (like a raw power bus).

     

    My rule is that I should be able to tell 100% what is happening in the

    schematic when I print it out.  If you have to use EAGLE itself (by using

    the info command for instance) to figure out what is going on then the

    schematic is incomplete.

     

    I also have a preference for labels over spaghetti nets that are hard to

    follow when printed out.  Hope that helps.

     

    Cheers,

     

    James.

    --

    James Morrison  ~~~  Stratford Digital

     

    email:  james@eaglecentral.ca

    web: http://www.eaglecentral.ca

     

    Specializing in CadSoft EAGLE

    • Online Sales to North America

    • Electronic Design Services

    • EAGLE Enterprise Toolkit

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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  • Former Member
    Former Member over 15 years ago in reply to autodeskguest

    James Morrison wrote on Thu, 25 February 2010 09:52

    dingebre wrote on Wed, 24 February 2010 21:57

    The schematic I am "capturing" are based on public domain circuits

    for audio processing modules in a modular analog synthesizer. There are

    some standard power connection schemes which I intend to follow

    consisting of +/- 15 Vdc and ground. Typically, the +/- supplies go

    through a ferrite bead and a couple of filtering capacitors before

    hitting the PCB's power nets.

     

    What is the best way to make a power net for the PCB components

    bcause it is separated from the power input jack by the ferrite bead?

    If I connect the connector pins to the supply +15 and -15 nets, I can't

    use them on the PCB. So, what is the best net to use to PCB components

    to the other side of the ferrite beads? Should use one of the other

    available supply nets or make a unique power net?

     

    I have played with different ways to do it, and they seem to work,

    but as I'm new at this capture stuff, I'd like to know if there are

    standard or preferred ways to accomplish this.

     

    This image kind of shows what I mean.

     

    Hi David,

     

    There are a few ways to do it.  First, every signal name in EAGLE is

    global.  So if you simply name a net to a signal name it will be

    connected to any other net with the same name whether it looks like it or

    not.  So watch yourself there.

     

    So you have a pin connected to a ferrite that goes to a plane then you

    can do a few things:

     

    1)  name (and label) the net between the pin and the ferrite.  That can

    be helpful.

     

    2)  create a custom supply symbol that indicates  it's function.  This

    can work too and can help with readability if that net goes somewhere

    else (like a raw power bus).

     

    My rule is that I should be able to tell 100% what is happening in the

    schematic when I print it out.  If you have to use EAGLE itself (by using

    the info command for instance) to figure out what is going on then the

    schematic is incomplete.

     

    I also have a preference for labels over spaghetti nets that are hard

    to follow when printed out.  Hope that helps.

     

    Cheers,

     

    James.

     

     

    Yes, it helps a lot. Thanks James. In the software I have been using

    (competing commercial application), it was a real chore to do this kind of

    connection and I was a litte nervous as it seems so easy to do in Eagle image

    I wanted to make sure I wasn't missing something.

     

    David

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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  • autodeskguest
    autodeskguest over 15 years ago in reply to Former Member

    dingebre wrote on Thu, 25 February 2010 11:42

    Hi Olin, you're reading too much into the "design". This is not a real

    schematic.

     

    I'm only illustrating the power connections.

     

    It is still a good idea to keep in mind that neatness counts, especially

    when you are presenting to others.  Some may look past that, but why allow

    it to be a issue when it would only have taken a extra minute to make

    things more readable?

     

    Quote:

    I only ask a little patience. I'm very new to using Eagle and want to

    learn good habits. Would you maybe take a second look? I'd like some

    advice about how to handle the power nets on the "real" circuits I'd like

    to work on.

     

    I don't use specific parts at all to label power nets.  I don't treat power

    nets any different from other nets that are drawn in separate pieces,

    although I've seen others use explicit power symbols commonly.  In Eagle,

    nets in the schematic are automatically connected if they have the same

    name.  To show airwires in a Eagle schematic, I name the nets and then use

    DRAW LABEL to show the net name in the schematic.  It's important to use

    DRAW LABEL instead of TEXT because DRAW LABEL shows the true net name as

    Eagle understands it.  If you change the net name, the text drawn with DRAW

    LABEL will automatically change.

     

    For power nets I use names like "5V", "-12V", "BATT", or whatever I think

    will be most descriptive in context of that schematic.  I also like to show

    power connections on top, ground on the bottom, with signal from left to

    right to the extent this can be reasonably done.  Keep in mind that the

    schematic is not only to define the machine readable connections to Eagle,

    but it is also the primary documentation of your circuit to humans.  As

    such, neatness and clarity are very important considerations.

     

    Quote:

    Should I do it kind of like in that illustration? Use the supply

    library  +/- 15 for the plug and then a generic supply symbol to connect

    the +/- supplies on the components? Or is there a better way?

     

    You'll probably find as many opinions as people.  There are several

    reasonably "right" ways.  I've tried to explain what I do, but I recognize

    there are other ways that others prefer.  As long as Eagle understands the

    connections, there aren't hidden gotchas for making changes, and your

    circuit is easy to understand from the schematic, then it's a acceptable

    method.

     

    You can take a look at http://www.embedinc.com/products/usbprog/eusb3.pdf

    as a example of how I do things.  The first page is the main power supply.

    Note all the named wires ending at the right side because the logical flow

    is out from the power supply.  You can see various other places in the

    schematic that connect to these power rails, usually coming in from the top

    or left as a simple visual reference that the power is coming in instead of

    being produced there.  Note that no explicit power symbols were used, just

    named nets with carefully placed labels.

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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  • Former Member
    Former Member over 15 years ago

    Olin wrote on Thu, 25 February 2010 12:49

    dingebre wrote on Thu, 25 February 2010 11:42

    Hi Olin, you're reading too much into the "design". This is not a

    real schematic.

     

    I'm only illustrating the power connections.

     

    It is still a good idea to keep in mind that neatness counts,

    especially when you are presenting to others.  Some may look past that,

    but why allow it to be a issue when it would only have taken a extra

    minute to make things more readable?

     

    Quote:

    I only ask a little patience. I'm very new to using Eagle and want

    to learn good habits. Would you maybe take a second look? I'd like some

    advice about how to handle the power nets on the "real" circuits I'd

    like to work on.

     

    I don't use specific parts at all to label power nets.  I don't treat

    power nets any different from other nets that are drawn in separate

    pieces, although I've seen others use explicit power symbols commonly.

    In Eagle, nets in the schematic are automatically connected if they have

    the same name.  To show airwires in a Eagle schematic, I name the nets

    and then use DRAW LABEL to show the net name in the schematic.  It's

    important to use DRAW LABEL instead of TEXT because DRAW LABEL shows the

    true net name as Eagle understands it.  If you change the net name, the

    text drawn with DRAW LABEL will automatically change.

     

    For power nets I use names like "5V", "-12V", "BATT", or whatever I

    think will be most descriptive in context of that schematic.  I also like

    to show power connections on top, ground on the bottom, with signal from

    left to right to the extent this can be reasonably done.  Keep in mind

    that the schematic is not only to define the machine readable connections

    to Eagle, but it is also the primary documentation of your circuit to

    humans.  As such, neatness and clarity are very important

    considerations.

     

    Quote:

    Should I do it kind of like in that illustration? Use the supply

    library  +/- 15 for the plug and then a generic supply symbol to

    connect the +/- supplies on the components? Or is there a better way?

     

    You'll probably find as many opinions as people.  There are several

    reasonably "right" ways.  I've tried to explain what I do, but I

    recognize there are other ways that others prefer.  As long as Eagle

    understands the connections, there aren't hidden gotchas for making

    changes, and your circuit is easy to understand from the schematic, then

    it's a acceptable method.

     

    You can take a look at

    http://www.embedinc.com/products/usbprog/eusb3.pdf as a example of how I

    do things.  The first page is the main power supply.  Note all the named

    wires ending at the right side because the logical flow is out from the

    power supply.  You can see various other places in the schematic that

    connect to these power rails, usually coming in from the top or left as a

    simple visual reference that the power is coming in instead of being

    produced there.  Note that no explicit power symbols were used, just

    named nets with carefully placed labels.

     

     

     

    Thanks Olin! I am used to a different commercial application which makes

    things like this so difficult. Right now, the hardest part of my learning

    curve is accepting how much simpler and more logical Eagle is compared to

    what I have been using. I keep expecting Eagle to be much more cryptic...

     

    Thanks for taking the time to share your thoughts. They are really helping

    me get in the "Eagle" mindset. Next time I put up project, I'll clean it

    up.

     

    David

     

     

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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  • autodeskguest
    autodeskguest over 15 years ago

    Surprisingly nobody has mentioned EAGLE's gotcha with respect to power

    supplies. EAGLE parts have named power supply pins that automatically

    connect to the net of the same name. Furthermore, on many parts these

    pins are hidden until you use the INVOKE command to bring them into the

    schematic.

     

    It becomes a problem when you try to use an opamp with say pin 4 defined

    as -15V in the part. Add this part into your schematic and that

    (invisible) pin is automatically connect to the net named -15V. If your

    -15V net is called VEE or VSS, no connection. Guess what happens when

    one part has a pin named VCC and another part has a pin named +15V and

    you need to connect both to the same +12V power supply rail...

     

    I don't like these implicit nets at all and I do not use them, but they

    are found all the time in the EAGLE library parts. I believe the newer

    versions of EAGLE may have an option to disable this behavior. ( I still

    use v4 ). Look in the EAGLE help for SUPPLY and POWER directions for

    pins to understand this a little better.

     

    I do use power supply symbols and I also frequently label the nets like

    Olin does. I document all power supply connections in the schematic

    along with their bypass caps, and never use the implicit ones.

     

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  • Former Member
    Former Member over 15 years ago

    Gary Gofstein wrote on Thu, 25 February 2010 18:56

    Surprisingly nobody has mentioned EAGLE's gotcha with respect to power

     

    supplies. EAGLE parts have named power supply pins that automatically

     

    connect to the net of the same name. Furthermore, on many parts these

    pins are hidden until you use the INVOKE command to bring them into the

     

    schematic.

     

    It becomes a problem when you try to use an opamp with say pin 4

    defined

    as -15V in the part. Add this part into your schematic and that

    (invisible) pin is automatically connect to the net named -15V. If your

     

    -15V net is called VEE or VSS, no connection. Guess what happens when

    one part has a pin named VCC and another part has a pin named +15V and

     

    you need to connect both to the same +12V power supply rail...

     

    I don't like these implicit nets at all and I do not use them, but they

     

    are found all the time in the EAGLE library parts. I believe the newer

     

    versions of EAGLE may have an option to disable this behavior. ( I

    still

    use v4 ). Look in the EAGLE help for SUPPLY and POWER directions for

    pins to understand this a little better.

     

    I do use power supply symbols and I also frequently label the nets like

     

    Olin does. I document all power supply connections in the schematic

    along with their bypass caps, and never use the implicit ones.

     

     

     

    Excellent point. I hadn't given that much thought.

     

    David

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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