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From: john larkin <jl@glen--canyon.com>
Newsgroups: sci.electronics.design
Subject: Re: EMC compliance question
Date: Fri, 11 Oct 2024 12:20:09 -0700
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On Fri, 11 Oct 2024 20:59:09 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:

>On 10-10-2024 23:11, john larkin 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.
>> 
>
>If your product can power usage is larger than 15W, then you get close 
>to nothing by using external SELV supply, because then a lot of the 
>demands on safety are back in play
>
>> 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.
>> 
>> 
>>>
>>> Lastly, it's just "good engineering" -- and great experience -- to
>>> go through the process so you know what to *avoid* in your
>>> future designs.  (ditto for safety requirements)
>>>
>>> Increasingly, I am seeing extra scrutiny on devices that CAN "talk"
>>> to ensure they aren't talking to anyone that they can't *justify*.
>>> "Why are you phoning home?"  "Why are you initiating HTTP requests?"
>>> "Why are you trying to resolve some oddball domain name?"
>>>
>>> [These, of course, are a lot harder to "guarantee" without (and
>>> even *despite*!) releasing full sources.  Especially for OTS/FOSS
>>> OSs that may have been preconfigured (for your convenience) to
>>> support services having communications requirements that you
>>> of which you may be ignorant!]
>> 
>> Software certs on top of hardware certs?
>> 
>>>
>>> Assume your customer is going to need/want to certify his
>>> use of your device and give him a leg up in that process,
>>> pre-sale.
>> 
>> For a small company making a modest number of some test instrument,
>> full certs will multiply development cost. That may be why I don't see
>> a lot of small instrument companies in europe.
>> 
>> The guys I was working with in Oxford laughed at me when I asked if
>> our atom probe system would need to be CE tested. "CE means Cant
>> Enforce."
>> 
>
>Some just takes the risks. If you are caught it can be an expensive 
>risk. On the other hand, I have never heard of a case where the company 
>went bankrupt. Have heard of large fines, but nothing that killed the 
>company

What's crazy is how expensive the CE specs are. I can buy one PDF for
$600, and it will reference a bunch of others. Recursively.

These specs have the force of law. It's like being forced to pay to
know what's legal or not.