[RFI] "No RFI" LED bulbs

Kim Elmore cw_de_n5op at sbcglobal.net
Wed Aug 16 20:17:10 EDT 2017

This interesting.

I've been switching o LED Christmas lights and was originally worried 
about RFI. I"m not certain how these work: Some provide FWB 
rectification while others provide only have-wave rectification. But, 
it's obvious that these don;t have a built-in PS. As far as I can tell, 
these things are RF-silent. I hear no change at all when I turn them on.

LED light bulbs are different because they have their own switching PS 
inside. I've used mainly Phillips, a few Cree and couple of no-names 
and, so far, haven't heard a thing form them. I've also replaced 
fluorescent tubes with LED equivalents and they're also quiet (both the 
kind that requires wiring around the ballast and the kind that will use 
a SS ballast). The same goes with CFLs. Sounds like I should thank my 
lucky stars!

Kim N5OP

On 8/15/2017 6:25 PM, Jim Brown wrote:
> I suspect the RFI problem is caused by a poor quality power supply, or 
> the use of AC to drive the LED directly.  I've used a lot of the LED 
> strips that Wired Communications sells at hamfests, mostly in the 
> western US. I use five of them to light my shack, powering them from 
> the 12V battery that is float-charged from a linearly supply.
> Last month, I mounted two strips on a shelf to light the area around 
> my computer desk, and, by accident, grabbed a 12VAC wall wart (in 
> other words, just a transformer) to power them. The RF noise was VERY 
> strong. Replaced the transformer with a 12VDC linear supply and the 
> noise went away.
> Of course, a switch-mode power supply would also generate noise.
> 73, Jim K9YC
> On 8/15/2017 4:08 PM, Ken Winterling wrote:
>> I have also heard some reports that the fluorescent or LED bulbs in an
>> opener can cause trouble with electric car door locks.  Some folks had
>> difficulty locking/unlocking their car doors while the opener lights 
>> were
>> lit.
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Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"In theory there is no difference between theory and practice. But, in 
practice, there is." //– Attributed to many people; it’s so true that it 
doesn’t matter who said it./

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