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From: Klaus Vestergaard Kragelund <klauskvik@hotmail.com>
Newsgroups: sci.electronics.design
Subject: Re: EMC compliance question
Date: Fri, 11 Oct 2024 20:59:09 +0200
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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