[RFI] Autopsy on a Lutron dimmer

Dale svetanoff at earthlink.net
Mon Dec 2 12:18:44 EST 2013


Sorry, the main reason that dimmers meant for incandescent and halogen lamp loads has nothing to with the waveform.  It has everything to do with the driver electronics that are inside the CFL or LED bulb assembly packages.  There are various ICs made these days that provide one-chip controller and driver solutions to the makers of these products.  SOME of the controller/driver chips have a special input pin designated as a dimming control.  From what I can tell, few CFLs have the ability, but most, if not all, of the LEDs have the dimmer ability.  However, dimming control needs to come from special dedicated dimmers - hopefully, that will change and existing standard dimmers can be used.  

I get many trade rags that advertise these controller chips.  I have no interest in them other than to note their functionality.  I might add that none (or very few) of these chips include RFI suppression - the end product maker is responsible for designing that part into the various bulbs.

As for your particular Lutron dimmer, I'd say try it.  I have no idea as to whether Lutron includes RFI control in all of their products (but see Charlie's post).  If you do end up with a noisemaker, take it back and get one of the DIVA series.  

73, Dale

-----Original Message-----
>From: "xquercus ." <jeff at mossycup.com>
>Sent: Dec 2, 2013 9:52 AM
>To: Dale <svetanoff at earthlink.net>
>Cc: Charlie Gallo <Charlie at thegallos.com>, Rfi List <rfi at contesting.com>
>Subject: Re: [RFI] Autopsy on a Lutron dimmer
>It's good to hear about Dale's autopsy as well as the claim that
>Lutron is very "RFI aware".  Just yesterday I purchased a Lutron
>TGCL-153PH-IV dimmer and will be installing it sometime this week.  In
>my situation, if it's RFI quiet, great -- otherwise I'll just put the
>old single pole switch back in.  This seems to be a lower quality
>product than the one Dale disassembled.  There are no Torx screws for
>disassembly.  The unit is held together by plastic clips which are
>each locked closed by crushing a small piece of sheet steel.
>When I was at the big box store picking this up over the weekend, I
>was thinking about not only RFI but whether or not manufacturers have
>made any changes to dimmers in order to make them potentially more
>compatible with dimmable CFL and LED bulbs?  With an incandescent
>bulb, the output waveform from a dimmer probably doesn't matter much.
>I doubt one could tell the difference between an incandescent driven
>by a pure sine wave, a square wave (or a triangle wave for that
>matter) provided the average power was the same between the waveforms.
> In contrast, I wonder if the circuitry in CFLs and LED lights might
>require something more closely resembling a sine wave.  If this were
>true, then just designing a dimmer which provides a better quality
>output waveform might decrease harmonics.  IDK, just a thought.

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