Gerry Duprey wrote:
> Howdy,
>
> I have a person/client who wants to use one of my boards in a commercial 
> product.  They are concerned about getting FCC certification for it and 
> I really have no experience with it.
>
> I think they can "dodge" the UL stuff by simply using an external UL 
> approved power supply/wall wart (so everything inside the product is 
> 5volts), but as I understand the FCC stuff, if you have a 
> clock/oscillator over 9Khz, it needs to be certified.
>   
Mostly correct; there are a few exceptions. Be careful with Chinese 
wallwarts; they are famous
for stealing certs from a competitor. UL maintains a list of complying 
manufacturers. It is up to
you and your client to do the due diligence work here. "I didn't know" 
won't pass muster here.
A very well-known client of mine had to destroy thousands of 
bogus-certified wallwarts when
we investigated a few bad supplies.
> If anyone has gone through this process, I'd really like to hear some 
> details about it.  Particular questions:
>   
Many times.
> 1) Are there any exemptions for small batch/lot products (these will 
> mostly be "art works")?
>   
basically, no, unless they are special commercial products, such as 
diathermy machines, etc. My
robotics client was exempt since the product was used in an underground 
sewer (unable to radiate
in normal operation). If you are not selling the product, some protyping 
is OK; unless it interferes
with airplane comm services.
> 2) Did you have to do a lot of shielding?  The controller is a PIC 
> running at 8Mhz doing a lot of RGB LED PWM stuff (www.rgbled.org).  I 
> don't think it throws off that much RF, but...
>   
Actually, PMW DOES throw off RF. Any signal that changes state rapidly 
on a long conductor throws off RF when
the sharp edge occurs (a simplistic explanation, but it covers it). The 
PCB layout is the most important factor; if
you do much PWM, you will probably need to have a 4-layer PCB to reduce 
radiation (at least one layer is GND).
The 4-layer PCB usually drops radiation by 50% immediately... think 
about it, you'll see why. If you can internalize
the signals to an inner layer, you might crush the radiation entirely. I 
normally make 4-layer PCBs, but only a GND
layer is used; I place noisy signals on the internal signal layer, then 
provide a copper pour on top (or bottom, as
needed) to encase the offender.

I have never had to shield anything to pass FCC part 15 or 68, but I 
HAVE had to shield stuff to stop external
noise from getting into the product. Strong nearby radios can swamp 
uP-based prducts, and metal boxes don't
always keep noise out. Police-band long-range radios are especially bad.
> 3) Did you use one of those FCC certification shops?
>   
Yes, my favorite is Sid Sanders' shop in Tampa, FL: Timco Engineering. 
They are extremely competent and will
tell you what to do to get your product into compliance, yet their fees 
are very reasonable. Call 1-888-472-2424.
> 4) Do you have a rough idea how much the process costs?  This could be 
> for class B certification (residential)?
>   
Its been 5 years since I rode herd on it, but then it was about $1800 
for the complete service on a still camera
accessory. That project passed immediately, took less than a month.
> 5) Did you also get a CA certification too?  If so, was the pricing similar?
>   
CE Norms? or the Canadian Standards Tests? No, but later CE Norms tests 
passed, I was told. BTW, CE Norms is NOT
exactly the same as FCC Part 15 or 68. Canadian Standards is literally 
identical to FCC, and my remembrance was that CA
was included with FCC. Canada and the US keep their standards VERY 
close, so that free trade is easy to maintain.

> Of course, while all the questions are important, #4/5 are really what 
> are going to sink/float the product.
>   
Your client is right to do this; the FCC has become quite militant in 
enforcing radiation testing. I was at a Comdex show
one year when the FCC seized untested PC accessories and arrested a few 
executives on the floor. I think it was 1980,
if I recall. Surprised a lotta folks.

- - -

You can save a LOT of grief by doing some testing yourself. Get an 
allband radio or a "bug sniffer" and try to pick up
your product with it. I paid less than $100 for a nice "bug sniffer" 
from a kit company a few years ago, and it does a
great job of detecting radiation. If you can pick up a strong carrier 
more than 4 meters away, you probably have a
problem.


--Bob Axtell
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