I'm working on a board to add a -5v signal to an ATX power supply, so it can be used to power an Apple II. The design is based on SpeedyG's, but I wanted something I could just plug an ATX power supply into, rather than cutting it up. I've always wirewrapped or breadboarded, but I wanted to do a proper PCB, now that they're so easy and cheap. This is my first time using KiCad, first time doing a PCB layout, and I don't have any background in analog circuits, so I was hoping I could get some advice on the design.
This is the schematic, which is just a copy of SpeedyG's with the connectors added in:
This is what I have so far for the PCB:
If you spot any problems, I'd appreciate hearing. I also have some specific questions:
The Apple II power supply is rated for 4A at 5V. I made the power traces 2.7mm to match the pads. It looks like that gets me almost what I'd need for a 5A rating. Seem reasonable?
By default, KiCad wants to route these traces awfully close. My understanding is that the space between traces should be about equal to the width of the trace. Is that a reasonable rule of thumb for a design like this?
Can I get away with putting power traces at the same location on opposite side of the board? For example, if I ran that ground line at the bottom on the opposite side of the 5v line. If I space everything out the way I think it should be done, the board gets awfully big for what it is.
The area around the capacitors seems sloppy and too tight. Should I space that out more?