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Complete newcomer to PCB layout - where do I start?

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tautech:
Test points.
Once you've done a few repairs the one thing you like to add to your own designs are a few test points which is simple enough to do for TH and often just raising a component lead is enough to make a connection but you can't do that with SMD.

Instead I've found Keystone SMD test points to be very useful as you can place them most anywhere on a Net and assign their pads to it so to not have Net errors.
Your call as to how small you want to get these but I find 0805 a good size to work with as they are just large enough to get a probe hook onto without the need for grabbers if something smaller is used.

Once a design is proven these test points can be removed and used again if there is no need for them to remain on the PCB. Most of the bigger parts suppliers will stock them in cut tape quantities.
https://www.keyelco.com/category.cfm/Test-Points-Surface-Mount/Micro-Miniature/p/523/id/741

eti:
Thank you SO much, everyone who helped. I now have to work out what "power flags" are, and how to attach them to things; this is all a new language to me, replete with a whole new set of words and systems.

tautech:

--- Quote from: eti on November 25, 2021, 11:08:09 pm --- I now have to work out what "power flags" are, and how to attach them to things; this is all a new language to me, replete with a whole new set of words and systems.

--- End quote ---
Power flags, power Nets  :blah:
Your CAD program should have an assortment of them and if it's any good you should be able to assign custom names to them. Typically you might want a couple of power rails where VDD normally means a digital supply rail and you should be able to edit the name and add a voltage. Likewise with VCC that you might have positive and negative rails of the same voltage as is common with Opamps.
The trick to having the CAD program do all the work for you is to specify the correct power Net for IC supply pins and although some CAD programs hide IC supply pins when schematics are transferred to the PCB all the Net connections will be correct it you've set it all up correctly.

eti:

--- Quote from: tautech on November 25, 2021, 11:44:00 pm ---
--- Quote from: eti on November 25, 2021, 11:08:09 pm --- I now have to work out what "power flags" are, and how to attach them to things; this is all a new language to me, replete with a whole new set of words and systems.

--- End quote ---
Power flags, power Nets  :blah:
Your CAD program should have an assortment of them and if it's any good you should be able to assign custom names to them. Typically you might want a couple of power rails where VDD normally means a digital supply rail and you should be able to edit the name and add a voltage. Likewise with VCC that you might have positive and negative rails of the same voltage as is common with Opamps.
The trick to having the CAD program do all the work for you is to specify the correct power Net for IC supply pins and although some CAD programs hide IC supply pins when schematics are transferred to the PCB all the Net connections will be correct it you've set it all up correctly.

--- End quote ---

Ah, well that’s good but I’m still at a loss as to the specifics of what these “power flags” do, and when it’s apt to use them. Any help would be useful, as YouTube is hit and miss as regards finding a specific guide. Thanks

nctnico:

--- Quote from: tautech on November 25, 2021, 11:44:00 pm ---The trick to having the CAD program do all the work for you is to specify the correct power Net for IC supply pins and although some CAD programs hide IC supply pins when schematics are transferred to the PCB all the Net connections will be correct it you've set it all up correctly.

--- End quote ---
Back in the days when logic was powered from 5V, -5V and -2V power nets and hidden power pins where a good thing because you didn't need to draw all the power pins. Nowadays hidden power pins are horrible. Even a simple digital circuit with 3 chips (each 48 pins or less) can have a 4 or 5 power nets.

The nicest things about the power net markers / symbols is that they connect across sheets. A net typically is local to the schematic sheet it is on (like a variable declared static in C). You'll need to use off-sheet ports to transport a net to other sheets. Power nets which use a power net marker / symbol don't need that.

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