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Gadget Gangster vs Parallax design decisions? Which board has better power/decoupling — Parallax Forums

Gadget Gangster vs Parallax design decisions? Which board has better power/decoupling

rwgast_logicdesignrwgast_logicdesign Posts: 1,464
edited 2012-03-10 04:53 in Propeller 1
Ok in the quest to design a board that OC's well ive really been looking at schematics and how caps are layed out while trying to learn as much about the process of decoupling as I can so im not just blindly soldering caps on a schematic, may as well buy a kit. When I started writing this my question was does anyone know why GG prop platform uses 47uf cap while parallax boards use 10uf caps, then it hit me there VRegs are different part numbers so that is probably why lol. But the question still arises does anyone know why GG chose these caps and VRegs over the the ones parallax uses? Does anyone have a GG Prop Platform and if so have you noticed good overclocking results with it? Ive also noticed the regs on the GG boards are heat sinked while none of the parallax stuff is.

Comments

  • tonyp12tonyp12 Posts: 1,951
    edited 2012-03-09 15:14
    When it comes to bulk capacitors that is used to filter/store energy
    Larger cap is just a good design and going larger than the specs says does not hurt.

    But if you try to keep cost down when you make thousands of units
    you go with the bare minimum value and that can be smt mounted.

    Larger volt regulator you go with the model for what your expected amperage needs are, most smt models use the pcb copper as heatsink.

    With rf caps and I would say even decoupling caps you go with the value in schematic, not larger or smaller.
  • RaymanRayman Posts: 14,844
    edited 2012-03-09 17:04
    I'd guess 10uF is fine. I would seriously doubt adding more would have any impact on the ability to overclock...
  • Cluso99Cluso99 Posts: 18,069
    edited 2012-03-10 02:22
    It is not necessarily true that more capacitance is better. For instance, if you are supplying the 5v from a usb (pc) then the spec says you cannot have a cap >10uF. Putting a 1,000uF may well damage your pc. Putting 20uF is unlikely to do any damage, but I cannot say that in every circumstance that will work without problems. Everything depends on your circuit.

    A pcb with a copper plane located under, but spaced, below a perf board will do almost nothing. It may help emi, but under some circumstances can in fact act as a groundplane to an aerial and increase emi. Can anyone recomment some good books on the subject for rwgast?

    I have 40 years of design experience and back then there were really no books on the subject, so everything I learnt was from seeing lab results of my designs. After a while you pretty much know, but how do you explain this I am unsure.
  • LeonLeon Posts: 7,620
    edited 2012-03-10 04:53
    The Pulsonix PCB software I use can output files for analysis by Mentor Graphics Hyperlynx:

    http://www.mentor.com/products/pcb-system-design/circuit-simulation/

    It's rather expensive, though.
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