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Flickering bulbs clue to signal integrity problem

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Guru of Grounding
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re: Flickering bulbs clue to signal integrity problem
Guru of Grounding   9/1/2010 8:19:36 PM
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If shielded wires solved the problem, then it was not a magnetic field coupling issue but an electric field issue. At power frequencies, "shielded" cables do absolutely nothing to combat magnetic field coupling. The extremely low operating current of the NE-2 means that a long wire could easily couple (capacitively) enough energy from nearby high-voltage wiring to make it glow.

Dan Mitten
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re: Flickering bulbs clue to signal integrity problem
Dan Mitten   8/28/2010 3:15:51 AM
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This is a great story, with even greater educational value. WKetel, I agree the robustness of using a high voltage system was lost by allowing it to also be a very high impedance system, as well. Ah, nothing like adding a ballast resistor from time-to-time.

WKetel
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re: Flickering bulbs clue to signal integrity problem
WKetel   8/28/2010 1:26:22 AM
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What would have been much simpler and a lot less expensive would be to put a resistor across each neon lamp. Perhaps 10K ohms, although in PLC work we use 5600 ohm resistors. It totally prevents undesired triggering .

Dr. Phil
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re: Flickering bulbs clue to signal integrity problem
Dr. Phil   8/27/2010 1:30:34 AM
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Something we sometimes forget...we have resources among us we fail to utilize. Thanks Dwight for the reminder! p

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