OK, this is a continuation of a discussion that was drifting off topic in thread

http://forum.allaboutcircuits.com/showthread.php?t=10339

I do have some questions about the subject, and want to continue this line of query though.

I have this part:

It is a variable cap I want to use in a crystal oscillator I'm designing. The 2 front pins are the same, and the capacitor jumps the gap between them.

I have no idea who makes it, and frankly don't really expect it to be in anyones library.

If I could lay out the parts and define which pins connect to which that would work, but I've never used a circuit CAD program.

So where do I start?

 

I use Eagle, and it is really easy to add a component to the library. Just open the editor, and have a look how is the component composed (schematic + layout). Then you could edit it to the shape of your component, and save it as a different part.

 

So how do you define 2 different pins as being equivalent? Thanks.

 

First you create the Package and Symbol you want, and then create a new Device. On the right bottom you see a panel with different packages, so you click New, choose the one you made. Then you click Connect and make pairs of pins and pads.

 

Oh did you mean they the two pins are internally connected? I don´t think that is possible in Eagle, you just have to do the design as if they were really connected, even though Eagle doesn´t agree. Or you just leave the spare pin unconnected.

 

There is a fairly good tutorial at this link to sparkfun.com. You will need to scroll down to the section labeled Beginning Embedded Electronics Tutorials then check out Lesson 10.

hgmjr

 

So how do you define 2 different pins as being equivalent? Thanks.

Please give an example. Basically, my experience supports what kubeek wrote. I had a v.regulator that had 4 ground pins in a SOIC-8 package. You can make them all ground quite easily, but the airwire will show, just as it does for other ground connections.

If you post the dimensions of your cap and say which pin is adjust, I will make the device and try* to post the zip file for its lbr. John

*I have had horrible PC problems the past whole week.

 

I use gEDA/PCB (which is free).

For pins that are connected you would make them the same pin number.

My gEDA page is at http://www.luciani.org/geda/geda-index.html
My PCB footprint library is at http://www.luciani.org/geda/pcb/pcb-footprint-list.html

(* jcl *)

 

I would prefer to use a package that I don't have to capture schematics, I already have a method I like for schematics. If I can enter the packages and interconnect the pins as is shown in the lecture on EagleSoft http://www.sparkfun.com/commerce/present.php?p=BEE-9-EaglePCB that would be ideal. I'll be checking the other sites too.

 

If the method you have for schematics can generate a netlist then
you should be able to import that netlist into a PCB layout package.

(* jcl *)

 

I'll be glad to generate my own netlist by hand. I don't generate that many per year, and I have a backlog of schematics that I have already made that I truely don't want to redraw.

Is this somethng that can be done in Notepad? (He asks with crossed fingers).

BTW, I've updated the picture to show the pad layouts.

 

I see the update, but to draw a library device, I need the dimensions, inches or metric, for the mounting. Just something close. It may be in multiples of 0.050. All I need is the base and height of the triangle. John

 

I have this part:

It is a variable cap I want to use in a crystal oscillator I'm designing. The 2 front pins are the same, and the capacitor jumps the gap between them.

I have no idea who makes it, and frankly don't really expect it to be in anyones library.

Bill,
Just FYI, that looks like a Johanson design, perhaps a 5501 model, or maybe one of the nonmagnetics.
Their website is here:
http://www.johansonmfg.com/#
Click on the Air Trimmer icon on the right, and a PDF catalog file opens. The 5501 is at the bottom left.
Same deal with the nonmagnetics, yours might be a 59Hx or similar