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Old Jan 28, 2013, 09:14 AM
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EMF Shield

I want to use higher PWM on my ESC, so on someone's recommendation from this website I bought the following items to make a shield to protect my radio reception using higher Pulse Width Modulation. Should make the ESC more efficient. Especially at mid range throttle. I will solder the resistor to the tape and then wire that into the negative of the battery.
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Old Feb 03, 2013, 11:30 PM
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emi shield

if the copper foil isn't adequate, try solid ferrous material (tin can?) shield. When testing brushless EV motors, I had considerable noise problems which essentially disappeared when i shielded the motor wires with conduit. Multiple wraps with copper and braided cable wraps were not effective.
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Old Feb 04, 2013, 08:18 AM
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Wow, multiple wraps and conduit didn't do it? What did you use to test it?
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Old Feb 04, 2013, 11:54 AM
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I don't remember exactly, I did this about 15 years ago, but I think I used a oscope and a 3 phase ac power meter. The noise would cause random erroneous power measurements, when I shielded the motor lines with flex conduit the errors ceased. I used the scope to observe for hi freq noise which also ceased with flex line conduit shielding. Up to then I had tried many different shielding and grounding schemes of which none had worked reliably. Btw, in most cases double braided shields has worked, but in this test (20KW about 30' away) it did not. Seems that there was too many places for the RF to 'leak out' and couple. The flex line conduit created the best mechanical /electrical faraday cage type shielding. Anyway there were some theory arguements, but in the end, results is what counted and what won out.
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Old Feb 04, 2013, 03:58 PM
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How extreme did you shield the motor lines? Individually or all in one braided sleeve?
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Old Feb 04, 2013, 06:08 PM
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The 3 motor lines were internally braided (like a woman's pony tail) within the metal flex line conduit cable. Both ends of the cable were mechanically integrated to the connector's back shells, essentially creating a faraday cage from the power inverter housing to the load. At the time, it was a controversial cable design, since no other cable had been built that way. It may be hard to do the same for our RC models, since it would require a continuous faraday cage over the ESC, motor lines and motor. But, who knows, maybe not all that necessary (perhaps with very short motor lines) at our power levels. The above was done when I was implementing test equipment for GM's EV1.
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Old Feb 04, 2013, 06:32 PM
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Oh Ok. The guy who recommended my setup works for Disney building robots.
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Old Feb 16, 2013, 11:07 PM
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Flew three batteries through on 16K and no radio problems. Not sure how much a difference in efficiency probably a few percentage tops. Need to test with a watt meter.
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Old Jun 18, 2013, 05:23 PM
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I now fly this plane with my FPV regularly and have had no issues with it at all. I have flown it many many times and sometimes very far from me. I don't know if the shield was the reason or there wasn't anything to worry about to begin with, but I think this mod is worth doing and will incorporate it into other models when I get the time.
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