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Why pcbnew

Ken YapKen Yap wrote 10/23/2019 at 18:01 • 2 min read • Like

Why you should learn to use Kicad/pcbnew even if you don't plan to make an etched board

I have found that even if you implement your circuit on perfboard instead of manufactured board, it's worthwhile taking your schematic which you drew in Kicad/eeschema and going through the PCB design process, but not generating Gerber files.

The reasons are:

  1. By assigning footprints to all your components, you can get a realistic assessment of how much board space you need, and how the finished board will look.
  2. By strategically adjusting the placement of the components you can reduce the wiring required. You can even go back and make adjustments to the schematic, e.g. change the assignments of functionally identical units of a component, such as a multi-gate IC, to reduce the wiring complexity.
  3. An autorouter such as freeRouting (which I described here) can indicate the complexity of the routing. If you end up with lots of vias, you might want to adjust the placement.
  4. If you decide to manufacture a PCB in future you are in a good starting point.
  5. It's good practice for pcbnew. :)

Some examples:

DTL binary clock:

5371 clock:

One aspect is that with perfboard you can bend the component pins a little, but you can't reflect this in the footprints, which assume the official courtyard. You can see an example in the 5371 clock board above where I bend the LM7805 ground pin backwards. In the footprint the pins are in-line. To do this properly this you would have to design custom footprints. I just make do with some annotations on the layout on the "front silkscreen" layer. You aren't going to take this to a PCB fab house anyway but just print out the schematic and layout to follow.

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Discussions

EtchedPixels wrote 6 days ago point

I must admit I've mostly given up on perfboard because PCBs are now so cheap.

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Ken Yap wrote 5 days ago point

Yeah TBH my last PtP wiring experience with a complex circuit has so put me off this method of assembly. It would be faster to wait for the shipping. I still do small onesies like this https://hackaday.io/project/167443-crystal-tester on perfboard.

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