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Preferred power supply connections?

Former Member

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

 

 

 

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  • Gary Gofstein wrote on Thu, 25 February 2010 20:56

    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.

     

    Yes, this is a nasty hidden gotcha.  I do what Gary does, which is never to

    use implicit power connections, at least not on purpose.  Unfortunately

    they can still bite you if you forget a connection.  It also helps to never

    use the Eagle supplied libraries.

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  • Gary Gofstein wrote on Thu, 25 February 2010 20:56

    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...

     

     

    Good point Gary.  That certainly is part of the discussion.

     

    Quote:

    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 ).

     

     

    Do you have any more info for turning this off?  I'd love to do that as it

    always scares me even with my own libraries.  My rule of thumb is if you

    can't tell exactly how the circuit should be connected from a printed

    schematic then your schematic is incomplete.

     

    I took a brief look and couldn't find how to turn this "feature" off.

     

    Cheers,

     

    James.

     

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  • i recall that Klaus said it will be coming, probably in the next v5

    release, maybe already there. i think he said it will be a eaglerc option.