[RFI] RF Noise Free LED Lighting

[KD7JYK DM09]

> Not sure if this info has been shared. They are advertising LED lighting
> which is noise free!

This brings up something I ran into several years ago.

Most LED lighting seems to produce noise due to the switching mode power 
supply.

I doubt any of us suspect the crystal within the LED itself to generate 
noise, but I suspect that happened with some automotive LED lights I bought.

I don't recall the brand, and I may no longer have them, but...

I replaced the backup lights in a sedan with LED equivalents.  They were 
bright white in color, inexpensive, purchased from O'Reilly auto parts.

They were simple in design, a molded plug and holder, the LEDs were on a 
flat PCB about the size of a quarter.  Two wires could be seen 
connecting the PCB with LEDs to the pins on the plug, a pretty straight 
forward design.

No electronics could be seen, although there may have been an SMT 
resistor on the board.  The light operated on the typical 12VDC provided 
by the vehicle.

When the vehicle was put into reverse, broadband RFI in the form of a 
loud, harsh hissing noise could be heard from an FM transceiver, into 
the mid-500 MHz range.

I didn't try to quiet them, or do any further analysis.

Kurt