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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: EMC compliance question
Date: Wed, 09 Oct 2024 19:21:54 -0700
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On Wed, 9 Oct 2024 21:29:09 -0400, bitrex <user@example.net> wrote:

>On 10/9/2024 7:18 PM, john larkin wrote:
>> On Wed, 9 Oct 2024 19:03:28 -0400, bitrex <user@example.net> wrote:
>> 
>>> What's the deal with the "CPU board" exemption?
>> 
>> Where is there such an exemption?
>
>It's under the section on sub-assemblies:
>
><https://www.ecfr.gov/current/title-47/part-15/subpart-B#p-15.101(e)>
>
>A "CPU board" as defined previously is considered a type of sub-assembly.
>
>As a hypothetical say someone sells a product that's a PCB with a PIC on 
>it and some relays that has e.g. RS-232 port and terminal blocks to 
>connect to other stuff. It's in some sense a functional product, but the 
>user must at least connect it to some load of their choosing for it to 
>actually do anything. And they can put it in a housing if they wish, or 
>not, whatever.
>
>Is this still a "sub-assembly"?
>
>
>>> "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?

Do you really care?

My Brit friends say that CE means Can't Enforce.

It's been a long time since I saw an FCC truck bristling with antennas
snooping around.