Re: EMC compliance question

On 13/10/2024 10:30 am, john larkin wrote:

On Sat, 12 Oct 2024 23:30:46 +0100, John R Walliker
<jrwalliker@gmail.com> wrote:
 

On 12/10/2024 18:07, john larkin wrote:

On Sat, 12 Oct 2024 12:25:27 -0400, bitrex <user@example.net> wrote:
>

On 10/12/2024 11:22 AM, john larkin wrote:
>

48 is super common now. All our phones are PoE powered, which is
typically about 54 volts. Digikey sells warts up to 65.
>
The phones are cool. I can take one to Hawaii and plug it in and it
works just like it does here.
>
I imagine that europe has tens, maybe hundreds of millions of PoE
devices with the chinese version of the CE mark molded into the case.
>
So if european manufacturers realy have to do all the CE certs and
testing, they have one more reason that they can't compete with
imports.
>

>
So as of 2019 it looks like the US rules are similar to the European
"can't enforce" rules in that the manufacturer takes responsibility for
everything and it's up to the mfgr how and what tests they perform to
determine compliance:
>
<https://www.electronicdesign.com/technologies/test-measurement/article/21209868/recent-developments-in-emc-legislation>
>
This makes it sound like it's not too expensive to do some basic
compliance tests on a small-volume product in house:
>
<https://incompliancemag.com/emc-bench-notes-how-to-use-spectrum-analyzers-for-emc/>
>
Need a 1 GHz-ish spectrum analyzer at least as the main tool which
aren't exorbitantly expensive nowadays.

>
I can buy a spectrum analyzer and a surfboard antenna for under $1000,
and can take a product out in the country and do an open-field test
and crudely ballpark its EMI signature.
>
CE requires screen room testing and more quantitative measurement.
>
The reality today is that few products are honestly certified for EMI
or safety, and life goes on pretty well. If a product causes massive
EMI problems or hurts people, civil and criminal liabilities apply.

>
My experience differs.  Every product that I have been involved
with has been independently tested by Intertek or a test lab of
similar status.
  > It's impressive how few EMI problems there are in real life.

>

Maybe that is because many products are actually tested and compliant.
I can remember when audio equipment was very susceptible to
interference from many sources.  Those days are mostly gone.
I have come across exceptions of course.
>
John

 Most audio equipment is digital now.

Most of most audio equipment is digital nowadays. The inputs aren't, and neither are the outputs. Domestic audio equipment usually gets it's input as a digital data stream - FM radio is an exception - but creating that input depends on analog microphones.
--
Bill Sloman, Sydney