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PostPosted: February 26th, 2020, 10:18 am 
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Joined: December 14th, 2013, 2:19 pm
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Don't use NM cable (Romex) for ANYTHING that radiates noise back into the power line (like SMPS, except for well designed ones like Dave B's). You are adding an antenna to a noise source. Use armored cable or metal clad cable, BX or MC. Seen it too many times. Not always a matter of noise on a common circuit with a sensitive load, the source and "receiver " can be on opposite phase circuits and still have unwanted communication. I've diagnosed and fixed this as part of my job.

Unfortunately, so many devices, like Jim's cheap-ass Chinese LED lights are in use that such noise is everywhere now.


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PostPosted: February 26th, 2020, 10:28 am 
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I suspect the only products made today that do not have switching power supplies is high(er) end audio gear, and even quite a few of those are using switching supplies.

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PostPosted: February 26th, 2020, 11:05 am 
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Given that and the slim chances that general use appliances, fixtures, etc. are ever likely to improve absent regulations requiring it, the only practical solutions are improved shielding AND filtering of our gear, DIY or otherwise.


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PostPosted: February 26th, 2020, 12:11 pm 
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I ran into an interesting situation using the X10 protocol which sends control info over AC lines for home automation. When I first started using it the results were OK. Over time, communication got worse. I determined it was from all the other newly added electronic equipment that was drawing power off the AC line but also had noise filters at the input. They reduced noise into and out of the equipment but also reduced the X10 signals trying to get across the AC lines. So it is not a simple situation. Stuart is correct that you have to take action at every step along the way. If you have good power supply design on your equipment it should largely be immune to line borne noise but still potentially will have problems with air borne noise. Having tight fitting enclosures that are properly grounded will help, but the devil is always in the detail.


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PostPosted: February 26th, 2020, 12:25 pm 
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Location: Parkville, Maryland
tomp wrote:
It depends on if you want source mateial that is not on any broadcast. It extends past what cable can provide and goes into Netflix and Amazon presentations over the web such as the SciFi show The Expanse on Amazon Prime TV.


I get that -- it's just that I have no interest in any of the cable or FIOS offerings. Never had. What turned me off to cable TV a long time ago was the promise that with cable there would be no commercials to deal with.

That promise lasted only about two years. When away on business and I am forced to view TV via cable (or satellite) there are just as many annoying commercials as there is on over-the-air broadcasts.

To add insult to injury their stuff is compressed -- not so with over-the-air.

So -- why underwrite cable services when the revenue from advertisers does just that? I have friends that do not realize they can get over-the-air digital TV and are shocked that the option is available to them.

Retail salesmen for the most part do not realize that option is available.

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PostPosted: February 26th, 2020, 12:48 pm 
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All HDTV available to you in your home is compressed to fit into a 6 MHz portion of a QAM channel. All the same, regardless of what Verizon tries to tell you.

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