🚀 go-pugleaf

I'm not a lawyer, nor do I do FCC certifications for a living, but based
on what I have read (including a copy of part 15 Subpart J, some time ago),
I'll try to answer best as I know.

In article <221@scdpyr.UUCP> hpoppe@scdpyr.UUCP (Herb Poppe) writes:
+---------------
| 1) Is every "device" used in the home that contains a "computer" (micro-
| processor, microcontroller, etc.) consider a "Class B computing device"?
+---------------

Yes. Notice that it doesn't have to be a computer. The definition is
(approx.) "any device which generates or uses radio-frequency energy"
not otherwise covered in some other specific FCC rule. "Radio-frequency"
in Part 15 Sub J includes digital pulses at a rate of 10 KHz or higher.

+---------------
| Is that fancy microwave oven, washing machine or toaster(?) containing
| a single-chip micro have to be certified by the FCC?  If not, what are
| the rules associated with allowing such devices to be exempted.
+---------------

Yes, unless there are specific Parts or Sections in the FCC Rules which
take precedence. For example, wristwatches (which typically use 32 KHz
crystal oscillators) are specifically exempted from Subpart J (but not
from Subpart C and other Parts).

+---------------
| 2) A micro is just a (relatively) high speed digital circuit. Certainly
| other high speed digital circuits that are not "computers" also generate
| RF energy that could interfere with radio/TV reception. If such circuits
| appear in products used in the home must they be certified as Class B
| computing devices? If so, what is considered "high"?
+---------------

Yes. "High" is anything over 10 KHz. For example, that includes such things
as the vast majority of infrared remote control units, since they use digital
techniques and >10 KHz pulses. (Even though the IR *light* is not covered by
the FCC Rules, the LED *driver* circuit is.)

+---------------
| 3) How is the "hobbyist" affected by the rules? Can I "homebrew" a system
| and be legal?
+---------------

There are other Subparts of Part 15 which concern what you can build and
use "for yourself". Part 15.C is (I think) if for what have been traditionally
called "Part 15 devices", that is, short-range radios, radio-control, and
the like. I think you may be able to use 15.C for home-built devices, but
don't hold me to this one...

Part 15.J is for "computing devices" (broadly defined), and because they are
more likely (due to their manufacturing volume) to cause interference, the
radiation limits are more stringent than for 15.C devices. (It may even
apply to home-built "computing devices", but better check the regs.)

The Class B radiations limits are (roughly), measured at a distance of
3 meters from the device:

	30-88 MHz:	less than 100 uV/m
	88-216 MHz:	less than 150 uV/m
	216-1000 MHz:	less than 200 uV/m

and no more than 250 uV conducted into the power lines (0.45-30MHz).

In any case, the ultimate test is that thou shalt not cause harmful
interference to other services or to your neighbors.

(Really, even these limits aren't too stringent! You often can't listen
to a weak radio station a few feet from a Class B device.)

+---------------
| If so, can I make systems for my friends?
+---------------

I don't THINK so...   ;-}   ;-}	

But check the regs. (They're easy to get. Call the U.S. Government Printing
Office and say you want a copy of the "FCC Rules and Regulations, Part 15
Subpart J". They'll sell you whatever's the enclosing volume of the Rules
which contains 15.J. You may want to look at *all* of Part 15...)

+---------------
| Can I describe such a system in the hobby press and be legal?
+---------------

Sure. You're not "building" anything. Anyone can publish information
(within broad First Amendment limits). Look at magazines like Modern
Electronics or Hands-On Electronics, which run several construction
projects per issue. "Ciarcia's Circuit Cellar" in Byte does this.

It WOULD be polite to provide a warning to potential builders that they
are liable for the consequences of any violations...

+---------------
| If so, can I offer "kits" for the described project at cost? for a profit?
+---------------

Wups! Now we're back to manufacturing! I think it's "No", and "No".
UNLESS... you have the whole think FCC type approved for "home
construction" (as Heathkit and some others do for some of their
computer kits). Such is possible, but not cheap.

I know, it sounds like the FCC suddenly became "bad guys". (NOTE! Way
back in 1982, when this finally went into full enforcement!) But for
years before, they'd been getting increasing numbers of complaints
about interference with radio & TV from folks whose neighbors had
small computers, etc. (Some of the early Apple-II's and S-100 systems
would wipe out low-numbered TV channels!) They decided to study the
expected growth in home electronics, and to set rules that would
insure that they wouldn't have to be in the middle of millions of
interference complaints and enforcement actions (which the FCC is
simply NOT staffed for!). The proposed Subpart J rules were circulated
for several years, and even after they went into effect, several
computer companies (including Apple) were able to get exceptions/extensions
for a couiple more years, on the grounds that compliance would cost too
much. By now, most everyone is up the learning curve on how to build
Class B confoming systems, and it's no big deal... except for the
raelly little guy such as yourself.  (Sorry!)


Rob Warnock
Systems Architecture Consultant

UUCP:	  {amdcad,fortune,sun,attmail}!redwood!rpw3
ATTmail:  !rpw3
DDD:	  (415)572-2607
USPS:	  627 26th Ave, San Mateo, CA  94403



Rob Warnock
Systems Architecture Consultant

UUCP:	  {amdcad,fortune,sun,attmail}!redwood!rpw3
ATTmail:  !rpw3
DDD:	  (415)572-2607
USPS:	  627 26th Ave, San Mateo, CA  94403