[ARC5] externally generated noise from switching controllers.

[Dennis Monticelli]

I agree with John's assessment of spread spectrum. Taken to the limit, they
only end up raising the overall noise floor.  But in a world where analog
comm modes in effect must share spectrum with random digital pollution, a
spread spectrum RFI reduction technique is less onerous to narrow band users
like hams than the alternative.  It is still evil, but the lesser of the
evils.  As for evading the law, the FCC Part 15 rules themselves are
outdated and inadequate in their protection of any weak-signal authorized
spectrum user.  The original rules never contemplated the extensive use of
digital "unintentional radiators" in such close proximity to weak-signal
users.  Manufacturers can comply with Part 15 yet the RFI problem is only
mitigated, not eliminated.  Meanwhile, unintentional radiators keep
multiplying like rabbits in our homes and neighborhoods.  I don't have a
solution to this madness. The quest for energy efficiency is the major
driving force behind PWM control techniques and that trend will only grow
stronger.

Dennis AE6C

On Wed, Jun 9, 2010 at 6:19 AM, J. Forster <jfor at quik.com> wrote:

> Soapbox Mode On:
>
> IMO, the spread spectrum switchers are EVIL. They are, philosophically,
> equal to "Dilution is the solution to pollution" in the chem engineering
> business. They are a way of evading the law and getting away with it. What
> you wind up with is a raised noise floor everywhere.
>
> Soap Box Mode Off.
>
> -John
>
> =============
>
>
>
> > My company is a leading maker of LED drivers.  The switching style
> > controllers have to pass FCC Part 15 just like everything else.  The bad
> > news is that passing does not insure RFI low enough to satisfy hams or
> > other
> > so-called "weak signal" spectrum users.  Part 15 did not contemplate such
> > ubiquitous use of "unintentional radiators" when it was first drafted.
> > The
> > good news is that some manufacturers are trying to get below FCC limits
> by
> > using sophisticated spread spectrum techniques which are less onerous to
> > narrow band users like ourselves.  But overall, it is kind of a losing
> > battle we hams wage as switch mode controllers of all types invade our
> > homes
> > and offices in the form of lighting, HVAC, solar arrays, and flat screen
> > TV's to mention just a few.
> >
> > Dennis AE6C
> >
> > On Tue, Jun 8, 2010 at 9:03 PM, Brian Clarke
> > <brianclarke01 at optusnet.com.au>wrote:
> >
> >> OK, Les,
> >>
> >> It's just that this email stream started off with concern about the
> >> amount
> >> of RFI generated by household lamp dimmers, not that generated by the
> >> new
> >> CF
> >> lamps. That's why my question about dimming LEDs. My lad wants to dim
> >> LEDs,
> >> too, and I have told him the dynamic range is very small - perhaps 3:1
> >> at
> >> most.
> >>
> >> 73 de Brian, VK2GCE.
> >>
> >> Les said:
> >>
> >> > Hi Brian,
> >> > These lights are on or off.  There is no control over intensity -
> >> except
> >> > by changing the series resistor.  If I was going to control the
> >> intensity
> >> > I would do a very nasty thing.  I would connect an X2 rated cap (or
> >> series
> >> > of X2 rated caps) in series with the primary of the power transformer.
> >> > (Or alternately a big fat inductor).>
> >> > Les
> >> >
> >> >
> >> In response to Brian's:
> >> >>
> >> >> What dynamic dimming range do you get with these LEDs?
> >>
> >>
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