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Harsh conditions, can it be done? — Parallax Forums

Harsh conditions, can it be done?

yarisboyyarisboy Posts: 245
edited 2011-02-22 02:19 in General Discussion
The application I'm evaluating must have the circuits shielded in a steel can to protect them from magnetic fields. For the same reason communication (out only) must be optical/serial. Here is the real kicker. I need to pot and balance the module to withstand up to 10,000 RPM. I know the Air Force has done a lot of work to perfect gun tube launched satellite electronics but I don't know how much info like that is available from the private sector. The electronics/software is no challenge at all but my processor of choice would be the Propeller due to the 3.3 voltage required. A potting compound I use to use from Masterbond was good to 10,000 PSI compressive (pricey though). The assembly should not really see any shock loads on top of the static centrifugal force field.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2011-02-21 16:59
    Depending on the magnetic fields you expect, you may need a soft iron magnetic shield like mu-metal. A steel can may not work well enough
  • localrogerlocalroger Posts: 3,452
    edited 2011-02-21 17:21
    How big is your assembly and how far from the axis? At that RPM it makes a huge difference, you don't have to get very far out before you're seeing 100G accelerations. And what is the magnitude and frequency of the magnetic field? Electronics are in general pretty immune to even very strong EM fields of audio frequency. If you're not trying to measure the output of a wheatstone bridge you can probably get away with no shielding at all.
  • yarisboyyarisboy Posts: 245
    edited 2011-02-21 19:45
    For consumer applications I would be able to build around a shaft of 1-1.5" diameter. This is the size of machine where experimentation should start. I'll have to make a dumb prototype recorder just to find the true magnitude of the signal I need to measure. I'll need to know both a low frequency (less than 1.5 Khz worst case)
    and the magnitude of a small voltage signal.
  • TonyWaiteTonyWaite Posts: 219
    edited 2011-02-22 02:19
    Hi Yarisboy,

    I did some magnetic testing for a 320MB/s ultra-320 SCSI system. It was in a 6mm-thick aluminium box. Even at levels of magnetic field equivalent to a ship being degaussed there was no perceptible effect.

    Good luck,

    T o n y
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