🚀 go-pugleaf

Hullo--

Having taken my first product through the rigors of FCC testing recently,
I am delighted to inform you that the answer is an unqualified "maybe."

The clock-speed exception is probably safely ignored since the FCC
defines a "digital device" as something that uses _digital techniques_
and employs timing signals or pulses whose frequency exceeds 9 KHz.  In
other words, any useful embedded-controller device will interest the FCC.

The useful exceptions center upon where and how the circuit is going
to be used.  Anything designed to be used _exclusively_ on a car,
train, or other moving vehicle is exempt from the emissions testing
requirements.  Anything used _exclusively_ in an appliance (smart
toasters, programmable blenders...) is also exempt.  Industrial
controls, low-low-low power gismos ( < 6 nW), and non-commercial
medical equipment are exempt.  Finally, if your product is meant to be
battery-powered and has no sources higher than 1.705 MHz, then you're
free and clear.  

If you want to consult the applicable canon, call the G.P.O. and order
47CFR parts 0-19.  You'll be interested in section 15 in this case.

If you aren't lucky enough to qualify for the above exemptions, then
I can refer you to a good testing lab.  One thing I strongly suggest,
however, is to avoid designing your own switching power supply: the
"conducted emissions" standards of the FCC (how much switching noise
can appear on the AC mains) aren't kind to the uninitiated.

Good luck!
--Cliff

-- 
| Cliff Bowman     |(501) 968-2232 Voice | As of 1 December, 1992, I was |
| Electronics Wonk |(501) 964-6118 Pager | approximately $1,017,077 shy  |
| Innovation Ind.  |(501) 968-7986 Fax   | of being a millionare.        |