So I have this problem. Suppose I have a 2n3055 power transistor that I am placing off the PCB on a large heatsink. I have a pad on the PCB for a line that comes in to the collector (via a wire); same for the base. The emitter goes to an aluminum housed resistor that’s also mounted on the heatsink (so no need for a pad that represents this side of the resistor on the PCB). The other side of the resistor then mounts on the PCB. So basically, I need a PCB footprint for the 2n3055 that has 2 pads and one for the resistor that has a single pad. Is it possible to do this? I seem to get errors if the number of pads for the schematic symbol doesn’t match those on the PCB footprint.
It’s a little more work, but I would create a custom library component for this situation. You might be able to copy/paste the original schematic drawing parts into your library so you don’t have to redraw them. Otherwise, I don’t know of a way to tell Eagle that it needs a special footprint.
One alternative might be to place the components as though they are on the board and only use the holes you actually need. That would waste some board real estate, but then you wouldn’t need to redraw and create a custom footprint.
I think I will just design alternate PCB footprints that collect the pads together in a row (so the 2N3055 will have 3 oval pads in a row and the resistor will have 2 in a row). I can then just connect the pads to the part via wires or just leave them be (e.g. connecting the emitter to one side of the resistor). I just have to mark them to make sure that I leave the correct pads blank if I intend to do this. Thanks.