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FAQs / Re: shielded stepper motor cable or not?
« on: September 07, 2008, 05:08:00 PM »
Dave,
If a junction box or just mounting a board inside something ok with lining it. You didn't say, but with a fan, I assume
you talking about a controller box and that one I would make out of metal or at the very least have a metal plate for one side of it. This way you have a nice metal conductor and it's not paper thin. The fan shouldn't be a problem as we have used ones for PC's.
If the fan has brushes then your generate noise. May or may not cause any problems. The opening for the fan should have a metal mesh screen which serves to keep something from getting into the controller but it also helps to keep an
electrical mechancal interference (EMI) from being conducted onto say a sensitive board inside. The screen is attached to make contact with the metal box and the box is grounded. The metal screen acts as a shield ( interferes with any electrical field trying to enter from outside the box) and it hopefully goes to ground. The screen openings ?? 1/2 or 1/4 wavelength of the EMI frequency ?? Been a while since I was up on this stuff so hope I'm not to far off base.
Those "E" electrical guys know all about this stuff.
Maybe I'll post some pictures of RF, EMI pictures just for kicks. ( No it won't look like a snow storm )
RICH
If a junction box or just mounting a board inside something ok with lining it. You didn't say, but with a fan, I assume
you talking about a controller box and that one I would make out of metal or at the very least have a metal plate for one side of it. This way you have a nice metal conductor and it's not paper thin. The fan shouldn't be a problem as we have used ones for PC's.
If the fan has brushes then your generate noise. May or may not cause any problems. The opening for the fan should have a metal mesh screen which serves to keep something from getting into the controller but it also helps to keep an
electrical mechancal interference (EMI) from being conducted onto say a sensitive board inside. The screen is attached to make contact with the metal box and the box is grounded. The metal screen acts as a shield ( interferes with any electrical field trying to enter from outside the box) and it hopefully goes to ground. The screen openings ?? 1/2 or 1/4 wavelength of the EMI frequency ?? Been a while since I was up on this stuff so hope I'm not to far off base.
Those "E" electrical guys know all about this stuff.
Maybe I'll post some pictures of RF, EMI pictures just for kicks. ( No it won't look like a snow storm )
RICH