help using express PCB schematic program

[mordechai]

I am just drawing up my first schematic using this program, and I want to put places on the schematic showing that there should be a pad leading to a wire that will send power to the indicator LED off of the 9V power rail.  I also want to make sure that when I do the layout, there are a few extra ground pads available.  Can anybody tell me how to do this?  The online help option isn't terribly helpful (too much info to sort through, and I'm not familiar enough with the software to make sense of it!).

[R O Tiree]

In ExpressSCH, open the component library and select "Connector - Wire connection" and place it into the appropriate spot on the schem. By default, it expects this to be labelled "W" and a number, eg "W3", but you can name it whatever you want, really.  "GND1", "GND2", "+9V", "LED+", "LED-", etc would be good for what you want?

Later, in ExpressPCB, you should select "Connector - Wire connection (0.035 inch hole)" from the component library and then pop a few of them around the board in appropriate places and then label them exactly the same as the ones on your schematic.

Job done.

[mordechai]

Thanks so much, very helpful.

[mordechai]

One more question -- on my schematic, I have a few variable resistors/trimpots, and I want to assign lug numbers to the various points on each component...having a hard time figuring out how to do that.  Any tips?

[davent]

You'll need to ungroup the component, next click anywhere else on the workspace to deselect the component. Double click on the dot at the end of a pin, a bubble/box should open up showing the pin number along with a box to check that will show/hide  the pin number, select the box to show, do the other two pins then highlight the whole package and group to make component.

[R.G.]

It looks like "FreePCB" does the necessary stuff. I haven't tried it but it has design rule checking, including against the schematic for shorts and open (that is, traces not yet routed), and allows the other necessary stuff, including producing Gerber output. And it's free.

http://www.freepcb.com/

[R O Tiree]

In ExpressPCB, select from the Pad menu 0.080" Round pad with 0.035 " hole.  Lay down 3 of them, 0.1" apart.  Double click the first one and hit "Auto-assign to Pin 1" and hit "OK".  Repeat for the other 2, so you now have 3 pads labelled pins 1, 2 and 3.  Click and drag through the whole lot and then pull down the "Component" menu then select "Group to make PCB component".  Double-click the new component and name it "VR" and hit "OK".  Go back to the "Component" menu again and select "Save custom component" and name it "Potentiometer Pads".  This will save it for future use.

As long as you name all the pots on your schematics "VR" and a number (eg VR2) then ExpressPCB will correlate those pots onto your PCB layout.  This, of course, assumes that your pot pads are in a straight line, right next to each other... if you need to spread the pads out, select your pot and then select "Ungroup PCB component".  Spread the pads out to where you want them, then select one of them, press and hold Ctrl and select the other 2.  All 3 pads should be highlighted grey.  Group them together again, re-name them what that pot was before and you should find that your continuity should be as before.

Don't be shy about asking further questions - there are more than a few ExpressPCB users here who will be glad to help.

[R O Tiree]

It looks like "FreePCB" does the necessary stuff...

I got as far in the FreePCB help file as, "Entering netlist files manually is tedious and time consuming..." (I paraphrase...) The author then goes on to describe his tedious and time-consuming method of printing out a schem, then checking off pins with a yellow highlighter and typing a netlist out in Notepad manually.

No schematic editor, then.

[davent]

As a big aide to drilling the etched pcb, i set the hole size in all pad sizes, and no matter what the final hole size is going to be, to 20mil. This pretty much causes the drill bit to self center in the pad with the initial contact as long as you are relatively close. I'll drill all the holes through with a #71 carbide drill bit (and drillpress) which covers just about all the components i use in pedals. Where needed, it's easy to enlarge the pilot hole with a handheld Dremel and the correctly sized (HSS) bit when it comes time to load that pad.

dave