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| Complete newcomer to PCB layout - where do I start? |
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| PlainName:
--- Quote from: nctnico on November 26, 2021, 04:42:47 pm ---There are two things that need to be seperated here: 1) Hidden power pins: in modern designs these are a nuisance. Don't do this because it makes a circuit harder to debug due to the many different supply voltages and package variations in existence nowadays. 2) Draw all lines for a power net: don't do this, use power net symbols for this purpose or net labels if you want to save even more space. --- End quote --- Don't normally quote in full, but this can't be said too much :) |
| eti:
So am I to take it that labelling the 0V GND & the +5V rail as "POWER_FLAG", one for each of them, it tells the software "derive the supply from here"? |
| tautech:
--- Quote from: eti on November 28, 2021, 04:52:15 am ---So am I to take it that labelling the 0V GND & the +5V rail as "POWER_FLAG", one for each of them, it tells the software "derive the supply from here"? --- End quote --- Simply, yes. When you place/add a Power flag whatever its name it becomes a power Net and any device connected to that Net will show one of its pads properties as being so. For an IC that's connected to that power Net you can edit the devices properties to hide power Nets and in some programs you can do this globally and still the connectivity will show when you transfer the design to the PCB. In a lot of cases to keep the schematic tidy you'll use power flags rather than run power traces everywhere. |
| eti:
Could someone give me a clear but definitive explanation of the following, please: What is a "net", exactly? What is "mil" and "thou", and how do they differ from millimetres etc? So grateful, this noob. |
| tautech:
--- Quote from: eti on December 05, 2021, 06:42:48 am ---Could someone give me a clear but definitive explanation of the following, please: What is a "net", exactly? What is "mil" and "thou", and how do they differ from millimetres etc? So grateful, this noob. --- End quote --- Technically a Net is each and every connection between components. However a power Net can of course connect to many components. Some such as GNG and power Nets need be named and for IC's their power pins should be assigned to the appropriate Net. Mil = thou = 1/1000th inch ~40 mil = 1mm. Mil is a US term as in Milli inch I believe whereas thou is of European origin. |
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