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Electronics Absolute PCB noob looking for an education

Discussion in 'Modding' started by LePhuronn, 4 Jan 2019.

  1. LePhuronn

    LePhuronn Member

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    Hi all.

    I'm toying with the idea of making up a custom PCB to split a 5-wire SATA power input into a pair of 5-wire SATA power outputs and a trio of 2-pin 12V outputs for short runs of LED strips. It'll save a lot of space, a whole mess of wiring and look pretty damn fine to boot :grin:

    But my experience extends as far as a couple of etched copper boards at school over 20 years ago, so I'm looking for advice, guidance, points, etc. Start at the very beginning, assume I know nothing (because I don't).

    All I know right now (I think) is the following:
    • PCB will be tucked away in the 7mm or so gap I have underneath the motherboard and a hard drive mounting plate (the PCB will be attached to that plate), so there will be zero airflow.
    • Based on 1oz copper, I'm think I'll need 2mm wide traces to safely send about 2-3A through the PCB in those cramped conditions. Although I'm using a Samsung SSD and Seagate SHDD (1 amp each tops), one of the LED strips might pull a good 2 amps on its own.
    So where do we start? What do we do?

    Looking forward to hearing from you all.

    Cheers!
     
  2. Boscoe

    Boscoe Electronics extraordinaire.

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    I would download Eagle and start playing with it, follow some tutorials. Once you have an understanding of how it works you need to look for the PCB footprints of the components you want to use. If they do not exist in the provided libs, you need to make them from the datasheetsof the parts you want to use. Once you’ve finished the layout, you create the output files also called GERBERs. Now send them to a fabrication house like PCBWAY, Seeed or JLCPCB. I wouldn’t bother with OSHPARK. Get the boards shipped to you and solder them together.

    I am an electronic engineer, I can do this for you, but I’ll have to charge .
     
  3. LePhuronn

    LePhuronn Member

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    Cheers Boscoe. This thing is a glorified y-splitter so there's no components, just holes to trace together (although I might look for some right-angle 2-pin Dupont connectors for a it of swish :p )

    As you're an electrical engineer, let me ask this: am I barking up the wrong tree here thinking I can just trace together some holes and solder in some 18AWG wire? Am I going to "dirty" the power in any way? I don't have the knowledge or the space to start putting in capacitors and whatnot to smooth the power out if nonsense occurs (but we're talking a couple amps tops on 12V).
     
  4. Boscoe

    Boscoe Electronics extraordinaire.

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    These are just standard 2.54mm pitch headers so it'd be very simple.

    You'll be fine having the power run across the PCB, as long as the traces are wide enough, you'd have to go pretty small to cause problems. It's surprising how much current you can get through a trace as it's often such a short distance. You don't need any capacitors.

    I would potentially just go for pads rather than holes. The wires are then running in the same direction as the PCB so sits flatter without the strain on a 90 degree bend in the wire. Something like below. You need vias (~0.5mm) in the PCB for strength, pads are easy to rip off.

    [​IMG]
     
  5. LePhuronn

    LePhuronn Member

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    Soldering wires to pads would slash the overall height of this thing by half, I'll have a look.

    I found a trace width calculator. 3 amps at 12V, 50 degrees ambient temperature at 1oz copper reckons 1.76mm wide traces.

    I'll go and have a play with Eagle now - the limitations of the free version are still more than sufficient for what I want to do.
     
  6. Nexxo

    Nexxo Queue Jumper

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    KiCAD and EasyEDA are freeware PCB design programs that are also worth looking into.
     
  7. LePhuronn

    LePhuronn Member

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    Cheers Nexxo!
     
  8. Byron C

    Byron C *psst!* This guy is a loser!

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    Back when I wanted to start doing electronics more seriously, I started watching some of the Contextual Electronics courses. There's a "Designing a PCB in KiCad in 20 minutes" video here, which I haven't seen but might be worth a watch.

    I'd definitely recommend getting to grips with KiCad. It's not as fully featured or mature as something like Eagle, but it's totally free and doesn't have the restrictions that free version of Eagle does.
     
  9. Sam__

    Sam__ Member

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    This is the calc I use for PCB trace width but your numbers look alright. stick a 2.5mm trace on it and you'll have some overhead up to around 5A.
    https://www.4pcb.com/trace-width-calculator.html
     
  10. LePhuronn

    LePhuronn Member

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    Cheers Sam, useful to know.
     
  11. LePhuronn

    LePhuronn Member

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    Ooh, thanks Byron. Gonna go whip up a Sunday sammich and have a crack at that.
     
  12. Xlog

    Xlog Active Member

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    Also Saturn PCB toolkit is a nice application to have (for various pcb/cooper properties calculations)
     
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  13. Sam__

    Sam__ Member

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    I'm totally using that!! awesome.
     
  14. Altyn10000

    Altyn10000 New Member

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    Hello, can attach simple drawings of that do you want to do? It will be much easier to give useful advices with visual attachments.
    As I understood you want board with one sata f right angle that splits to one sata m right angle and two 2-pin connectors. First you need to find connectors and their specifications. 2 pin connectors pretty standard 2.54 mm, but sata varies from manufacturer to manufacturer. For sata nowadays there is 12V, 5V, and GND in use, 3.3V not used anymore. For standard 2 layer fr4 pcb with thickness of 1.6mm you can use bottom for GND and on the top layer draw power planes (not just traces but polygons) the only minor minus that you need good soldering iron.
    If you board will be less than 5*5 cm, price from services like allpcb, jlcpcb and many others that mentioned above will be not expensive.

    For reference, here my post and how I did custom pcb for front panel. https://forums.bit-tech.net/index.php?threads/cm-haf-932-front-panel-rejuvenation.346787/
     
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  15. LePhuronn

    LePhuronn Member

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    Thanks Altyn, I'll look at your log when I get home :thumb:
     
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