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RE: Noisy dimmer switches and RFI
I've
also found with my low voltage lights that the transformers make a big
difference.
In the
lounge I have a futronix dimmer connected to 7 low voltage lights, each
with
it's own transformer.
The
transformers were originally powermark cheapo crappo ones at about 3 quid
each.
I
replaced them with mode transformers at about 15 a piece and the noise was
_significantly_ reduced.
Now
all I have to do is find the dosh to replace the 12 in the dining room
and
the 12 in the kitchen :-(
Tony
Hi
Tracey,
Any
dimmer will generate noise. It is caused by chopping up the mains and
suddenly
applying current. It can be lessened by the judicious use of chokes to
limit
the rate of rise of current thereby limiting the magnetic field created.
Better dimmers have larger chokes.
One
way of trying to minimise the interference is to ensure that Live and
Neutral
follow the same path (something that doesnt always happen with house
wiring)
thereby creating a balanced circuit. Because the conductors are in close
proximity and carrying identical but opposite currents the radiated
magnetic
field will be effectively cancelled.
The
majority of interference is radiated by the WIRING not the dimmer. The
dimmer
is the cause but it is worsened haveing a bloody great aerial attached
!
Keith
With
reference to the attached, is it possible to get these
Lutron
dimmers
in the UK, or has anybody got any suggestions about
"clean"
dimmers
that are available in the UK?
Tracey
>>
>> Are
there any particular brands or specific models of dimmer
>>
switches(!!) that don't pollute our low frequency bands
with
RFI?
>>
>> 73,
>> Charlie,
N0TT
>>
>Yes, there are. The problem is that there are so
many styles and
models of
>dimmers---rotary knobs with switches at
the CCW end or with
push-in
>switches, sliders with or without
switches, and toggles. There
are single
>and double pole dimmers,
600W and 1000W (and more) dimmers,
dimmers for
>low-voltage
lighting, designer dimmers, and so on. I think you
get
the
>picture.
>
>Generally, the "good" units include
small
ferrite beads and
maybe
>capacitors, and often the product
description will mention the
RFI
>protection in some way.
Unfortunately, such switches often have
a (small)
>added cost
increment--so most people, unaware of what RFI is and
why
they
>should be concerned, buy price and get the cheapest units
from
Ace Hardware.
>
>Several years ago, I made up a test
jig
with a bunch of
different dimmers
>and a 100W bulb, and put a
portable AM radio next to the kludge.
To achieve
>a meaningful
comparison, all were single-pole, rotary knob, 600W
>incandescent
units---the most common denominator. I think I
had
a
>representative sampling---by no means was it
comprehensive.
>
>The difference between these dimmers in terms
of RFI was quite
>significant---stunning, really. My hands-down
favorite for a
plain vanilla
>rotary 600W single-pole incandescent
application was and is the
Lutron
>"Traditional" D-600 series.
Lutron claims "superior radio
frequency
>interference (RFI)
filtering" and I agree.
>
>I have since placed a half-dozen of
these in neighbors' homes.
To find the
>offending RFI generator, I
walk the neighborhood with a portable
AM radio
>tuned to the top
of
the BC band. The buzzer will often just leap
out at me
>as I walk
past a house. Most folks, when I explain my mission,
allow me
to
>replace their units, but there is a possible liability
factor
involved in
>not being a licensed
electrician.
>
>W.W. Grainger sells the D-600's for $5.14 in
singles. Their
stock number is
>4LX92 (white) or 4X603 (ivory).
The
3-way versions are the D-603
series:
>Grainger numbers are 4LX93
(white) and 4X852 (ivory) @ $7.84.
>
>There are also Lutron
toggle (AY-600 single-pole and AY-603
3-way) and
>slider (GL-600
single-pole and GL-603 3-way) units in that
series. These
>cost a
LOT more ($12.12 for the GL-600 to $54.90 for a 1000W
3-way
toggle
>unit), so I don't even consider them for freebie
replacements.
Ditto the
>"Designer" Series, which run from $16.26
to $91.45! As if these
were not
>enough, there are High Power
dimmers (to 2000W) which generally
sell to
>commercial and public
space applications and which can cost
hundreds of
>dollars
eaach.
>
>The relevant pages in the huge and wonderful Grainger
catalog
are 879-882. A
>whole tree died for each one of
these.
>
>The standard disclaimers apply---I have no personal
interest in
Grainger or
>Lutron. But Grainger is a toystore for
adult males, fer sherr.
>
>Aren't you glad you asked?
:-)
>
>Garry, NI6T
>
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