8 MHz dsPIC33F clock on stripboard?

Discussion in 'General Electronics Chat' started by tom66, Jul 11, 2010.

  1. tom66

    Thread Starter Senior Member

    May 9, 2009
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    Does anyone know if I can get a 8 MHz crystal on a stripboard connected to a dsPIC? The stripboard is only standard stuff, so probably has high inter-track capacitance, which is what I'm worried about.

    Thanks!
     
  2. sceadwian

    New Member

    Jun 1, 2009
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    Why even try? Knowing that this is bad it's simplicity itself to bend the leads for the crystal lines from the MCU straight up and wire the crystal and it's caps above the strip board, isolated completely. Problem solved and you don't have to worry about the parasitics of the stripboard.

    You're thinking too inside the box, strip board is flat, the world is three dimensional.
     
  3. tom66

    Thread Starter Senior Member

    May 9, 2009
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    Well, I suppose I could do that. It's only a prototype. But I have figured out that the internal 7.37MHz oscillator should work suitably well... it doesn't need to be high accuracy.

    Does anyone actually know the capacitance of stripboard?
     
  4. sceadwian

    New Member

    Jun 1, 2009
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    It's not static, it depends on the board, this is a prototype, again avoid the whole issue, bend the pins up and do the oscillator portion off the strip board. Or simply remove the rest of the traces on the strip board then you don't have to worry about the capacitance or inductance.
     
  5. womai

    New Member

    Jul 8, 2010
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    The inter-trace capacitance of even a large stripboard is just a few pF. Much less if you cur the traces to just their necessary length. Also you could reduce the capacitor values used in order to compensate for the added trace capacitance. But no need to get overly worried. I have successfully run PIC and dsPIC microcontrollers on stripboard and breadboards with external crystals and resonators up to 20 MHz, with no special tricks and precautions.

    Wolfgang
     
  6. sceadwian

    New Member

    Jun 1, 2009
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    womai, so the circuits you're speaking of will run perfectly well on both breadboard and stripboard using the same design?
     
  7. tom66

    Thread Starter Senior Member

    May 9, 2009
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    I can vouch to overclocking a PIC rated for 20 MHz at 33.33MHz on a breadboard, but I haven't tried stripboard yet.
     
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