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From: Klaus Vestergaard Kragelund <klauskvik@hotmail.com>
Newsgroups: sci.electronics.design
Subject: Re: EMC compliance question
Date: Sat, 12 Oct 2024 11:35:03 +0200
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On 11-10-2024 21:20, john larkin wrote:
> 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.
> 
Yes, I don't understand that either. I have found some standards 
"online", if I just need to look. If I need it professionally, I need to 
buy it of course