Homebrew PCBs

----- Original Message ----- 
From: "kilocycles" <kilocycles@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, March 18, 2006 4:00 PM
Subject: [Homebrew_PCBs] Pins and Pads for external connections


> I'm re-doing some components I previously created (in Eagle, but this
> probably applies to other CAD pacakages as well).  The actual
> components, MiniCircuits SBL-1 RF passive mixers require several
> signal to be connectected externally.  This is an 8 pin through hole
> device.
>
> Two of the pins are for discrete signals.  Two other pins are for one
> signal, and four pins are ground.  In Eagle, I've designated the
> ground pins as SUP (supply) and the other four as I/O.  I would think
> there should be a way to tie the two I/O pins together in the symbol
> that are supposed to be connected together extenally, but I haven't
> run across any symbols that tie pins together.  I have them tied
> pictorally in the Symbol drawing.  Also, I'm not sure if pads can be
> tied together in the Eagle Package for the device.  I can lay
> additional pads down that overlay and graphically link the ones
> defined for the pins, but they aren't logically connected when the
> Device is defined; they are just sort of lying there.
>
> Without tying the pins and pads together in the Symbol/Package/Device
> definition, I have to remember that the two signal pins have to be
> tied to the same external signal, and the four ground pins have to be
> tied to ground, and not leave one or more unconnected.  It's not a
> real big deal, just a convenience.
>
> There is a note in the Eagle Help topic on pins that states if any pin
> are defined on the Symbol as SUP (implying GND signal)that these will
> be automatically connected to GND as a net if a Supply symbol is used
> on the schematic; for example +12V, I presume. That's something else
> that's news to me.  I've used Supply many times, and I've yet to see
> any component automatically tie to GND.
>
> Any ideas?

In Pulsonix I can connect pins like that in the Footprint editor using a 
dummy net name, so I just have a four-pin schematic symbol - RF, IF, LO and 
GND. Perhaps you can do something like that in Eagle. Otherwise, you could 
just use additional pins on the symbol and connect them on the schematic.

Leon