Question about using ExpressPCB

[David]

I downloaded and started playing with ExpressSCH and ExpressPCB yesterday.  My victim was the Bobtavia.  I got the schematic created OK, although ExpressSCH couldn't deal with a center-tapped transformer!  I wound up just specifying pads instead.  Then I opened up ExpressPCB and linked to the schematic.  I would have thought that the act of linking would cause SOMETHING to display.  But NOOOOOO!  It appeared to be expecting me to lay the components out again.  I did part of it as a test, laying the components out like on the schematic.  Guess I'll need RG's book to do this right.

What is the point of linking to the schematic?  I saw no effect whatsoever!  Also, is there any way to scan a schematic into ExpressSCH?

[BILLYL]

I use this software to develop my PCB - but have yet master the schematic portion of the program.  For what I am doing the PCB software is fine.  

As for uploading a existing schematic - I don't think you could.  You can share schematics if it has already been drawn using the software.

BILL

[onboard]

copied from 'Help" files---Running the traces from component to component is simplified if the schematic and PCB are linked.  Embedded in ExpressSCH schematic files are wiring lists (called NetLists).  When linked, the ExpressPCB program highlights which pins need to be wired together.

David, definately nose around the Express help files, as there is definately some proprietary-ness here (as with any app). I haven't gotton to pcb layout yet so I'm not up on it.

For that Bobtavia transformer, for example, you can make your own which is fairly easy once you get the hang of it. Try downloading this and placing directly in the folder C:\Program Files\ExpressPCB\SchComponents_Custom , let me know if it works. Here's what it should look like..........



I pulled up the stock transformer, highlighted it, ungrouped with the "Componenet" drop menu, added the extra pin plus lines to ground for that particular schem, highlighted it again and saved as custom component from the "Component" drop menu again.  Seems like a hassle but it's really not.

[David]

So the obvious first step is to build the schematic with ExpressSCH to get the netlist.  OK, makes sense.  But then what happens?  You specify the components to go on the board with ExpressPCB and the netlist defines the connections?  Does that mean you have to have the PCB defined before you can link the schematic?  That's starting to make sense.  When I linked the schematic, the "PCB" was empty.

[bwanasonic]

Linking does not magically place components. It is really just a method for error checking net connections. I usually place all the parts I will need loosely around the edge of the board and name them as they are named in the schematic (R1, C2, etc. ) . Then link to the schematic. Now use the net connection tool :



to highlight what connects to what. You still need to do the actual layout yourself. I find it a pretty useful tool.

Kerry M

[Fret Wire]

Thanks Kerry, that's what I thought. I tried the same thing. I started with a simple fuzz face. I drew the schematic up, then clicked on check for netlist errors. It told me the Q pins weren't labled. I ungrouped them, but couldn't get them labeled. I'll have to go back over it.

[David]

Linking does not magically place components. It is really just a method for error checking net connections. I usually place all the parts I will need loosely around the edge of the board and name them as they are named in the schematic (R1, C2, etc. ) . Then link to the schematic. Now use the net connection tool :



to highlight what connects to what. You still need to do the actual layout yourself. I find it a pretty useful tool.

Kerry M

So then you wouldn't put an 8-pin DIP socket on the PCB for the LM386 in a Bobtavia, you'd call up the LM386 component itself, just like when the schematic was created in ExpressSCH?  This seems like double work.  I guess I'm not seeing what the advantage of using ExpressSCH is.  I COULD just go right to the PCB design -- not well, of course -- but I could.

[bwanasonic]

I guess I'm not seeing what the advantage of using ExpressSCH is.  I COULD just go right to the PCB design -- not well, of course -- but I could.

As I said, the advantage is getting some help making sure everthing is hooked up right. Kind of like a spell-checker. Seeing the nets highlihted can give a better idea on laying things out  too.

Kerry M