Beware of possible issues when installing some LED lights on your tractor

[Industrial Toys]

So, it may still desense onboard receivers given how close the lighting is and the radio antenna is probably only feet from the lighting too.

 

[W8BYA]

So, it may still desense onboard receivers given how close the lighting is and the radio antenna is probably only feet from the lighting too.

Absolutely.

 

[W8BYA]

Tonight I played with several different quick fixes to help eliminate the RFI from the trouble maker LED assm. Right off the bat a 0.15 uF cap across the power line did hardly anything. The same capacitor in parallel with a 100 pF & a 0.01 uF cap was just a hair better but still mostly useless.

All those caps in addition to a type 31 ferrite core with 5 turns started to make a dent but had a long way to go. Adding a type 43 core with 5 turns created the "water balloon effect". That is where some frequencies got a little better but other frequencies got a little worse. We call it that because you can imagine squeezing a water balloon in one spot to make it smaller but the balloon plumps out bigger someplace else.

It became obvious it was going to take a much more serious filtering approach. I quickly designed up a combination common-mode & differential filter using discrete capacitors and inductors and tried it out. The results looked promising enough to inspire me to refine the design and actually make the filter presentable. Below should be an image showing the spectral response of the LED with and w/o the prototype filter in addition to a baseline noise level.

The top (blue)trace is the LED w/o filter, the orange trace is the LED with filter, and the green trace is the noise baseline. That green trace shows ambient radio stations and other misc transmitters and other RF sources my loose wires were picking up. The plot basically shows that at low frequencies (like around the AM band) the LED RFI levels were reduced by about 55 dB (a factor of about 3 million times less power). Higher up in frequency near the CB band the levels were reduced about 30 dB (a factor of about 1000 times less power). Even higher up in frequency near the FM radio band the levels were reduced about 35 dB (a factor of about 3000 times less power). So I am thinking when I refine the filter these numbers will be even better.

 

[k0ua]

I have been hoarding ferrit cores out of scrapped equipment. I always wondered about the application implications.

Many of the cores out of scrapped equipment are not even ferrite. Many are just powdered iron. Like a T200-2.. Many of these will not do what you want to do. There is a lot to learn about ferrite.

 

[k0ua]

Howdy James. That is one nice thing about having several VNA's around the shop....I sometimes will purposely buy ferrites that are unknown when I can get them for a steal then characterize them myself, mark them and put them in the appropriate plastic drawer for later consumption.

You and I think alike as far as what things to try first. I had just made up a parallel combo of a 1 uF, 0.1 uF and a 0.01 uF caps and was ready to try it out when I rubbed my eye and managed to get some sawdust etc into my eye. I was using the chainsaw an hour earlier and must have had some small shavings still in my hair or hat etc. Anyway saline flushes did not help and I was in real pain so before I did more damage to my Cornea off to the ER we went. Just got home and the doc found 2 small slivers pinned into my lid.

Anyway, we will start with the caps for giggles but I am not going to hold my breath. If I am real lucky and it is a common-mode issue then the ferrite bead with multiple turns may help. I suspect I will end up needing a more robust LPF design. Should be interesting & fun to see what it takes.....stay tuned. 73

Yeah, might need a pi filter design. It will be interesting to see what you come up with. If you have a 2 port VNA (Vector Network Analyser) you are ahead of the game for figuring out what you might need. For those of you that thing we are speaking Greek, we are. Or more likely we are speaking Geek. But the point is that RFI issues can get pretty hairy pretty quickly. Of course you can try simple things and it MAY fix it, or a combination of things MAY fix the problem but IF and when it doesn't then you may need some analysis.

 

[k0ua]

Tonight I played with several different quick fixes to help eliminate the RFI from the trouble maker LED assm. Right off the bat a 0.15 uF cap across the power line did hardly anything. The same capacitor in parallel with a 100 pF & a 0.01 uF cap was just a hair better but still mostly useless.

All those caps in addition to a type 31 ferrite core with 5 turns started to make a dent but had a long way to go. Adding a type 43 core with 5 turns created the "water balloon effect". That is where some frequencies got a little better but other frequencies got a little worse. We call it that because you can imagine squeezing a water balloon in one spot to make it smaller but the balloon plumps out bigger someplace else.

It became obvious it was going to take a much more serious filtering approach. I quickly designed up a combination common-mode & differential filter using discrete capacitors and inductors and tried it out. The results looked promising enough to inspire me to refine the design and actually make the filter presentable. Below should be an image showing the spectral response of the LED with and w/o the prototype filter in addition to a baseline noise level.

The top (blue)trace is the LED w/o filter, the orange trace is the LED with filter, and the green trace is the noise baseline. That green trace shows ambient radio stations and other misc transmitters and other RF sources my loose wires were picking up. The plot basically shows that at low frequencies (like around the AM band) the LED RFI levels were reduced by about 55 dB (a factor of about 3 million times less power). Higher up in frequency near the CB band the levels were reduced about 30 dB (a factor of about 1000 times less power). Even higher up in frequency near the FM radio band the levels were reduced about 35 dB (a factor of about 3000 times less power). So I am thinking when I refine the filter these numbers will be even better.

View attachment 628834

Man o man. The power supply driver in those lights are noisy sob's . Keep at it and let us know how it goes.

 

[caver]

I picked up some old heavy duty fluorescent 277 fixtures from work many years ago. I've rebuilt a few for T8 bulbs to hang in my barn at my property and they are noisy. My barn is about the only place I might listen to the radio and I can't with those lights on.

 

[Industrial Toys]

I have replaced many brand new ballasts on Florescent lights to lower RFI to listen to a radio.

 

[Mike68]

I had a similar issue with my garage door opener. I put 100Watt equivalent LED flood light bulbs in the garage. Would occasionally leave them on for several days. So we didn’t come home in the dark.

Our garage door started having trouble opening with the remote. We changed batteries, remotes and messed with the receiver antenna. It was only by accident we put 2 and 2 together and found out the LED lights were the culprit.

They did not cause an issue when only on for a few hours. But if on for several days they would begin to emit some sort of interference and block the signal from the remotes.

 

[Threepoint]

[snip] For those of you that thing we are speaking Greek, we are. Or more likely we are speaking Geek. But the point is that RFI issues can get pretty hairy pretty quickly. Of course you can try simple things and it MAY fix it, or a combination of things MAY fix the problem but IF and when it doesn't then you may need some analysis.

Yep, James, that would be me! :confused2:

I'm following W8BYA's thread with great interest, and looking forward to the Cliff Notes solution. :laughing:

I get modest RFI/EMI from my six Asian-sourced aftermarket LED work lights on my cab tractor. The radio is a Pyle marine radio that receives AM/FM and NOAA weather broadcasts. The interference is actually the most irritating on the NOAA weather band, 162.40 - 162.55 MHz, but I listen to that only occasionally and for a few minutes at a time.

For several years, I've been intending to experiment with some cheap ferrite beads that I would order online and install on the power wiring at each work light. Hopefully my procrastination will be rewarded when one of you smart guys find something that works well, and that even I can install easily.