Radio Interference From LED Lights

[PILOON]

Speaking of RFI, where I live there is about 4-5 miles of hydro lines that make AM radio impossible to listen to.

Couple years back I complained to local hydro that RFI was interfering with my TV reception.
They arrived with a van that had a loop antenna mounted on the roof but were reluctant to run any tests trying to convince me that it was my house installation.
Fortunately it was dusk and very humid and you could see blue streaks jumping around the insulators.
They soon fixed that problem.

A fellow I once knew at Hydro research labs once told me that just about all porcelain insulators were badly decayed from ozone and acid rain. He also claimed that all cross tie hardware needed to be re-torqued as loose hardware created capacitance hence some interference symptoms. That is most noticeable on AM bands in poorer reception areas.

 

[The Fred]

I would worry about it causing problems with other modules and relays.

Some of the LEDs I've checked make HUGE voltage spikes. Buy yourself an inductor for each light to alleviate the problem.

Here's one that screwed up a John Deere loader, fixed by adding inductors. Folks those are 100 volt spikes! BAD stuff around electronics.

Regards, regrets if you don't fix it!

Fred

 

[supertaster]

I would worry about it causing problems with other modules and relays.

Some of the LEDs I've checked make HUGE voltage spikes. Buy yourself an inductor for each light to alleviate the problem.

Here's one that screwed up a John Deere loader, fixed by adding inductors. Folks those are 100 volt spikes! BAD stuff around electronics.

Regards, regrets if you don't fix it!

Fred

Good info. Thanks

 

[The Fred]

If I remember correctly those were Ebay LED lights that were advertised to work from 12-40 volts. At 12 volts those spikes were only around 50 volts, but at 24 volts watch out. I didn't want to try them at 40 volts.

Those spikes were back feeding into another relay on the same power circuit that made the machine do funky things.

I DO enjoy the small load current consumed by LEDs though as compared to equal lumens halogen lights.

Regards, Fred

CRTC Electronics - Inductors

 

[varmint]

Speaking of RFI, I had a buddy who lived in a cabin in the woods, but within sight of a massive FM radio station tower. You could literally pick up the broadcast in your fillings on damp nights, and his stereo couldn't make up its mind about which input it was using sometimes. Seems like they measured 4 volts of radio in the air, if that makes sense? This was 40 years ago, so forgive me if I am off here.

 

[clewis]

Speaking of RFI, I had a buddy who lived in a cabin in the woods, but within sight of a massive FM radio station tower. You could literally pick up the broadcast in your fillings on damp nights, and his stereo couldn't make up its mind about which input it was using sometimes. Seems like they measured 4 volts of radio in the air, if that makes sense? This was 40 years ago, so forgive me if I am off here.

Well, of course, radio transmitters work by inducing a small voltage on the receiver's antenna. But you're usually talking micro or occasionally a few millivolts. Not 4 volts. Except perhaps from a multi-mega/gigawatt pulse radar transmitter a mile or less away. Measuring voltages of RF transmitters on receiver/antenna assemblies is very very difficult to do, so unless it was a professional or proper radio amateur with the right gear, I highly doubt it. High impedance meters (eg: digital voltmeters) are somewhat tricky to use with disconnected wiring (an antenna effectively is), and they will often pick up inductive couplings by nearby house wiring with surprisingly high voltages. The term used is "ghost voltages". For example, if you flip a light switch off, and disconnect the light bulb, it's not uncommon to read 120V on the switched off hot wire - it's picking up a tiny bit from nearby wiring, the digital meter doesn't present enough load to short it out, and it looks like you have full voltage there. But if you connect the bulb (or any other load), the voltage disappears. Electricians have to be cautious relying on DVMs - voltage present _may_ not mean that the circuit is still live. This even happens in contact-free voltage testers sometimes. This doesn't happen with old fashioned "neon bulb" testers or analog meters. Probably your buddy picked up some ghost voltage induced from the cabin wiring.

Bad grounding and other issues/subtleties in building wiring will tend to accentuate these effects. Indeed, it's normal to see a few volts between ground and neutral EVEN IF they're solidly bonded together in the panel as they're supposed to be. However, if it's more than a few volts, you have a very severe and dangerous condition that MUST be checked out ASAP. Whisper "loose neutral" to the power company, and they WILL come.

 

[clewis]

I would worry about it causing problems with other modules and relays.

Some of the LEDs I've checked make HUGE voltage spikes. Buy yourself an inductor for each light to alleviate the problem.

Here's one that screwed up a John Deere loader, fixed by adding inductors. Folks those are 100 volt spikes! BAD stuff around electronics.

picture omitted

Regards, regrets if you don't fix it!

Fred

Am I reading that image right, you're seeing ringing at 5mhz? Right on the bulb? I'm a bit surprised that a brute force power circuit (with a tractor battery in it for heck's sake) could ring like that at that frequency.

 

[LSyooper]

View attachment 457906


The LED lights I installed interfere with the radio causing static. Has anyone had success with using ferrite core snap on assemblies?
The lights are currently connected using the factory wiring in the cab for the front and rear work lights.

Or, do you have other solutions?View attachment 457907

Does anyone have an answer to this? Supertaster, did you figure out a solution to your radio interference? I just recently installed 4" LED's on the front and rear of my tractor and also ended up with radio interference. I have found quite a bit of people saying they have the same issue but have not found any definite solutions. Sounds like the ferrite cores work for some and not for others.

 

[mcfarmall]

Interesting thread. I discovered this more or less by accident while camping. In 2015 I replaced all the bulbs in my travel trailer with LED lamps. I like to deploy a weather alert radio in my travel trailer while camping to keep abreast of changing weather conditions and it seemed that sometimes I'd get great reception in the trailer and sometimes not. Last summer while camping in Illinois, I was listening to the forecast in my trailer when I happened to turn on one of the interior lights and suddenly my weather radio was nothing but static. Turned the light off, weather radio was nice and clear.

My solution is to listen to the radio in the dark!

 

[Fallon]

I put a couple ferite cores on my LED light bars & radio power wires. It helped a bit on one (the least noisy one to start with), but not much on others.

It can't hurt to try, but don't count on it. Read up on HAM radio & RFI, it can be an insanely deep subject. I have my HAM radio extra license & still only get a bit of it.