Hi Mike,
Doing some quick reading there are lots of different variants of LED strip
lights, but I suspect the ones my neighbor has are low end in which all of
the smarts are in the controller and the controller does dimming using PWM,
and my guess would be that the PWM carrier frequency is 10 KHz based on the
RFI frequency repetition I'm experiencing (note that the RFI is very stable
with virtually no drift). I actually see that some companies recommend PWM
carrier frequencies for LED strip lights be 25 KHz and above for various
reasons so 10 KHz is definitely not a ridiculously high PWM carrier
frequency. I've never dealt with LED strip lights before so I was really
caught off guard yesterday and wish I would have looked at the actual strip
of lights closely whereas I just looked closely at the wall wart power
supply and the controller. I suspect my neighbors' strip lights are either
RBG or RBGW but that's just a wild guess on my part.
I'm going to send Steve at the ARRL pictures of the wall wart and
controller that I took which shows all the text I could find on them.
I will probably go back to my neighbors house at some point (maybe next
weekend if they are available) to take a closer look at the LED stirp and
also see if she can find her original packaging or amazon order details but
I need to be considerate because I'm dealing with her bedroom as well as
her daughters bedroom, in addition to her daughter still recovering from
her brain surgery.
P.S. I do have experience with PWM generated RFI from lots of different
devices, I've used lots of PWM devices in designs at work, and I also
designed my own PWM solar charge controller many years ago using a
microcontroller so I atleast have a decent technical background related to
PWM in addition to RFI as a result of it.
Just FYI, and 73.
Don (wd8dsb)
On Mon, Dec 2, 2024 at 6:03 AM Michael Carter <Mike.Carter@unh.edu> wrote:
> Don, you mentioned the suspected generator of RFI is the LED strip light
> 'controller.' You replaced the power converter with a linear bench supply
> to no avail.
>
> What features of the LED strip lights are governed by the 'controller'
> box? Pulsing of the string and/or dimming by PWM would be obvious sources
> of RF emission.
>
> Even though the problem was 'solved' by the owner discontinuing use of
> that LED strip light, I am curious about the mechanism of RF generation in
> the 'controller' box.
>
> Thanks, and 73,
> Mike, K8CN
>
> ------------------------------
> *From:* RFI <rfi-bounces+mike.carter=unh.edu@contesting.com> on behalf of
> Don Kirk <wd8dsb@gmail.com>
> *Sent:* Sunday, December 1, 2024 10:25 PM
> *To:* jim@audiosystemsgroup.com <jim@audiosystemsgroup.com>
> *Cc:* rfi@contesting.com <rfi@contesting.com>
> *Subject:* Re: [RFI] RFI 80 through 10 meters every 10 KHz tracked down
> to neighbors house
>
> CAUTION: This email originated from outside of the University System. Do
> not click links or open attachments unless you recognize the sender and
> know the content is safe.
>
>
> One correction, I probably should have said they were LED strip lights
> whereas I called them string lights.
>
> Don (wd8dsb)
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
>
> https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.contesting.com%2Fmailman%2Flistinfo%2Frfi&data=05%7C02%7Cmike.carter%40unh.edu%7C5379c334644940bedb2208dd12811904%7Cd6241893512d46dc8d2bbe47e25f5666%7C0%7C0%7C638687067890900117%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=3tpH0VS3sztTc%2Bc%2B9YNQ0FL%2BtLr5ZJ3BJGq524xdPhk%3D&reserved=0
> <http://lists.contesting.com/mailman/listinfo/rfi>
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|