[sdiy] FCC And Other Testing

Richie Burnett rburnett at richieburnett.co.uk
Wed Jan 13 15:13:29 CET 2021

Ben gave a good summary.

There are broadly two aspects of CE/FCC compliance testing.  "Immunity" and 
"Emissions."  Immunity refers to whether or not your device malfunctions 
when exposed to some external interference from another piece of equipment. 
Emissions refers to whether or not your device produces interference that 
might cause someone else's equipment to malfunction.  For example, an 
immunity problem might be that a Digital Synth reboots every time the guy 
next door uses his stick welder, or your house heating boiler fires up.  An 
example of an emissions problem might be that the Digital Synth radiates 
enough interference to block radio reception in the area.  Clearly the 
implications of each type of failure are different, and so are the ways you 
might find out about them if you haven't done formal testing.  A typical 
customer would probably put the odd Synth reboot down to a firmware bug or 
just overall poor product design, and it would probably generate feelings of 
frustration and a customer complaint at worst.  On the other hand, the 
jamming of nearby radio reception is potentially a much bigger problem, 
particularly if those radio communications are for a critical service like 
Fire, Ambulance, Police or Aviation.

There have been cases where poorly designed or old malfunctioning television 
sets have done things like crippled the broadband service in an entire town, 
and even initiated a full blown coastguard search-and-rescue mission after 
radiating on a satellite monitored international distress frequency.  Whilst 
these cases might seem mildly amusing when you think about the authorities 
taking away some poor old lady's ancient B&W TV set, the consequences of 
non-compliance can potentially be drastic.


-----Original Message----- 
From: Ben Stuyts
Sent: Wednesday, January 13, 2021 11:05 AM
To: Steven Cook
Cc: Synth-diy at synth-diy.org
Subject: Re: [sdiy] FCC And Other Testing

I have some CE-related experience:

A CE declaration is written and signed by the manufacturer. Not by a testing 
house. The manufacturer must have a dossier proving that the device complies 
with all the regulations that are mentioned in the CE declaration. This 
shows they have done their due diligence making sure they comply with all 
the various directives (EMC, low-voltage, machine, etc). This could even be 
done without any testing at all, but by (meticulously documented) design. 
Although I have never seen that in practice.

Then there’s this grey area: In case of a module (or sub-component) of a 
system, there is something called a type-II declaration. This means that the 
manufacturer declares that the device complies to the regulations, if 
installed properly, etc. But it is up to the integrator/builder of the full 
system to check that it complies. Perhaps this is applicable to synth 
modules, I’m not sure.

The most important, if not only, regulations for synth modules would be the 
one related to the EMC directive. If you hire a testing house to do a full 
compliance (traceable) test, this can become costly. Many thousands of 
currency-units. But you can also ask for a pre-compliance test. An EMC-only 
test should be less than 500 I would guess, if they find no problems. They 
will also help you solve any problems. (You could even do this yourself, but 
it is both science and art, and you need some costly equipment.)


> On 13 Jan 2021, at 10:38, Steven Cook via Synth-diy 
> <synth-diy at synth-diy.org> wrote:
> Hi, I'm developing a Eurorack synth module which uses a microcontroller. I 
> recently asked a question on here about ground planes and someone mention 
> it might be tricky to get FCC approval, something I'd never even thought 
> about. Having looked into this, it seems like it could cost tens of 
> thousands of pounds just to get FCC approval, and that there are lots of 
> other sets of rules in other countries, such as CE, Industry Canada, VCCI, 
> CNCA, and EASC (to name a few).
> Realistically, do micro businesses selling Eurorack modules actually go 
> through all these convoluted and expensive test procedures?
> Regards,
> Steven Cook
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