RGB LED strips pollution

[TheCynicalCris]

Hi,

 

I've been trying with a few models of LED RGB strips but to my surprise, they pollute FM signals like crazy. Only my tuner connected to the external antena works properly when RGB is on, other three FM Tuners (all Technics branded) on indoor antenas receive a lot of pollution. Why RGB strips pollute so much on FM signal?

 

 

[GoodBytes]

4 hours ago, TheCynicalCris said:

Hi,

 

I've been trying with a few models of LED RGB strips but to my surprise, they pollute FM signals like crazy. Only my tuner connected to the external antena works properly when RGB is on, other three FM Tuners (all Technics branded) on indoor antenas receive a lot of pollution. Why RGB strips pollute so much on FM signal?

 

 

It's more the controller circuitry than the LED itself. Cheap circuitry at work that don't fully comply with EMC.

You can read more here: http://www.ledbenchmark.com/faq/LED-interference-issues.html

 

 

[ThatWheelchair]

that is kinda crazy but I think it has to do with the controller or receiver

[Syntaxvgm]

The controller yah. Some of my keyboards do this too. This seems to happen more with pwm. All either on or off seems to not cause this- Full red for example 100% brightness is fine. 

[straight_stewie]

8 hours ago, TheCynicalCris said:

I've been trying with a few models of LED RGB strips but to my surprise, they pollute FM signals like crazy

Anytime electricity flows, a magnetic field is created. This means that high speed switching circuitry, like data circuits, clock circuits, or switched power regulators (common in LED control circuitry) can induce electromagnetic radiation in the FM range.

[Unimportant]

22 hours ago, TheCynicalCris said:

Hi,

 

I've been trying with a few models of LED RGB strips but to my surprise, they pollute FM signals like crazy. Only my tuner connected to the external antena works properly when RGB is on, other three FM Tuners (all Technics branded) on indoor antenas receive a lot of pollution. Why RGB strips pollute so much on FM signal?

 

 

A constantly changing current level trough a conductor causes it to radiate electromagnetic interference. They use a PWM square wave to control the light intensity/color of these LED strips.  Square waves are a nasty waveform, EMI wise, because it contains a broad spectrum of frequencies up to very high frequency (harmonics). This, in combination with the fact that these strips and their supply wires are probably about the right length to make excellent FM radio antennas (+- 3meter/1.5 meter), is the cause of your FM radio interference.

 

This is why you often see arrays of ferrite beads or some other high frequency filter devices near I/O connectors on computer boards, etc. You'd want to keep the surface of your HF loops small and thus keep them off of (long) wires.