Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: legg <legg@nospam.magma.ca>
Newsgroups: sci.electronics.design
Subject: Re: EMC compliance question
Date: Fri, 11 Oct 2024 19:31:09 -0400
Organization: A noiseless patient Spider
Lines: 71
Message-ID: <gtcjgjlhuspq5aktltgrebvgdcqgkgvk36@4ax.com>
References: <67070ba9$1$1783$882e4bbb@reader.netnews.com> <ve9e5c$39rmc$1@dont-email.me> <dsfggj1a5m9mise9781qmh1roqv3pb68jr@4ax.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Injection-Date: Sat, 12 Oct 2024 01:29:03 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="4d28fb42aa6703784ad59a872c99590b";
	logging-data="4049432"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+vrqq5332U1r96YNOK9U8p"
Cancel-Lock: sha1:zVVqEZEAxaK9xu/eFu55CuYJrgM=
X-Newsreader: Forte Agent 4.2/32.1118
Bytes: 4038

On Thu, 10 Oct 2024 14:11:35 -0700, john larkin <jl@glen--canyon.com>
wrote:

>On Thu, 10 Oct 2024 13:41:07 -0700, Don Y
><blockedofcourse@foo.invalid> wrote:
>
>>On 10/9/2024 4:03 PM, bitrex wrote:
>>> What's the deal with the "CPU board" exemption?
>>> 
>>> "CPU board. A circuit board that contains a microprocessor, or frequency 
>>> determining circuitry for the microprocessor, the primary function of which is 
>>> to execute user-provided programming, but not including:
>>> A circuit board that contains only a microprocessor intended to operate under 
>>> the primary control or instruction of a microprocessor external to such a 
>>> circuit board; or
>>> A circuit board that is a dedicated controller for a storage or input/output 
>>> device."
>>> 
>>> So if one sells a board that has say a PIC on it and some support logic, and 
>>> the 9kHz+ signals are all internal to the uP (self-clock), but it's otherwise a 
>>> functionally complete design other than it's not in a housing, is that an 
>>> exempt product?
>>
>>Who is your customer?  If you are selling it as a *product*,
>>it is not a *compliant* product so your customer inherits
>>no certifications (because there are none).
>>
>>If your customer integrates it into *his* product, then
>>the responsibility for "product certification" falls on him
>>(so, you have saved *yourself* a few pennies on the certification
>>process and left him with any "problems" that your board may
>>pose to *his* certification).
>
>A few pennies for a certified test lab to do full certs?
>
>>
>>If you are selling to hobbyists, you *may* be able to get by
>>as a noncompliant product (the first case, above) -- so long
>>as none of your (few?) customers finds themselves drawing
>>the ire of neighbors, etc. when your device interferes with
>>their pursuit of life, liberty and happiness.
>>
>>But, you are still exposed as the seller of that noncompliant
>>product.  How likely will your customers "have your back"
>>if things get sticky?
>>
>>In the latter case, your customer (integrator) will *likely*
>>be thankful for any steps you have taken to certify your
>>"component" as he goes about looking for certification on
>>*his* composite system.
>>
>>Why do you think so many products are sold with El Cheapo,
>>off-brand wall warts instead of taking the power supply
>>design *into* the overall product?
>
>A wart relieves one of all the AC-line safety certifications. There
>are some big warts these days, including 48v ones.
>
>One can resell a cheap wart with the usual molded-in (usually fake)
>UN/CE/CSA markings, or let the customer buy their own wart.
>

A wart used in an EMC certification becomes part of it. Hence 
mrfs listing and retailing part numbers for suitable use.

Warts can be (and are) listed independently, to reduce 
potential testing and deployment gliches. A listed 
wart doesn't guarantee radiated compliance, only facilitates 
conducted performance on that one, main, port.

RL