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

[hawkeye08]

I agree. I shared my findings with my dealership and they were very thankful and said the information would be passed on. I feel good knowing that I brought some awareness to them about a subject that I doubt they had much experience with.

Also the thing that makes this more complicated is that as far as I know the radio that I had installed is not one that NH normally provides or has available. As stated earlier it is very possible that even these very noisy lights with a different radio would yield entirely different results. Again, EMC must be treated at the system level not an individual or component level matter.

Perhaps the dealer would "loan" you the LED lights they sell so you can test them? See if they have the same issues or part of their price is a internal filter that solves the issue?

 

[W8BYA]

He may also have a better radio. Most people only listen to one station. How about a tight band pass filter?

In this case a bandpass filter would not help at all because the RFI being generated covers the frequencies being received. If this were a matter of front end over load or mixing issues (spurious response performance) etc than a BPF might be in order.....but not here. It looks like the lights he has use filtered SMPS (like my red "Toro" light) where I hardly found any RFI at all. And his radio may have some powerline filtering which does not hurt at all.

 

[radios1]

I understand and we're on the same page.
Ok...
"The SMPS and LED's are all inside a die-cast aluminum enclosure. The issue is the SMPS contaminates (inadvertently) the 13.8 VDC supply (INPUT) voltage from the tractor."

What I'm trying to say in that simple drawing is do not supply LEDs tractor power. Instead tractor power to anode of diode. Diode cathode to LED supply.
I'd use one diode+cap each light.
Instead of 13.8v going to each LED you would have 13.1v. Scope this point. Cap value for lowest noise.
Simple...hopefully this diode/filter cap prevents feedback from LED back to tractor "B+".

I used ECG125 diodes all the time. 1000 prv, 2.5A.

for this, you should use fast recovery diodes, since the SMPS probably operates at 60 KHz, and standard recovery diodes would easily act like a low ohmage resistor at that frequency!..

 

[Fuddy1952]

Google "radio noise after LED install", or similar. Tons of information. Briefly looking at some information they mentioned the best LED assemblies are FCC approved and stamped.

 

[Fuddy1952]

for this, you should use fast recovery diodes, since the SMPS probably operates at 60 KHz, and standard recovery diodes would easily act like a low ohmage resistor at that frequency!..

Good point.

 

[W8BYA]

Perhaps the dealer would "loan" you the LED lights they sell so you can test them? See if they have the same issues or part of their price is a internal filter that solves the issue?

That is a great idea. I will ask them if they are willing to play.

 

[Industrial Toys]

I don't totally agree on the front end business. A tight, selective front end goes a long way to rejecting unwanted signal. We who used Motorola commercial FM rigs always laughed at the Hammy Hamster Rigs and their lousy front ends. We wouldn't have the RFI and intermod troubles that they did.

 

[W8BYA]

for this, you should use fast recovery diodes, since the SMPS probably operates at 60 KHz, and standard recovery diodes would easily act like a low ohmage resistor at that frequency!..

This particular SMPS operates up at 477 kHz and I found approx 1.6 V(p-p) RFI riding on top of the 13.8 VDC supply line. But as noted, when I tested 3 additional and different LED fixtures 2 out of the 3 had hardly any noise. Lab results matched field results when I took them outside, wired them one-by-one to the tractor and tuned various AM & FM stations.

 

[radios1]

This particular SMPS operates up at 477 kHz and I found approx 1.6 V(p-p) RFI riding on top of the 13.8 VDC supply line. But as noted, when I tested 3 additional and different LED fixtures 2 out of the 3 had hardly any noise. Lab results matched field results when I took them outside, wired them one-by-one to the tractor and tuned various AM & FM stations.

yep, that differentiates the good from the junk designs!. the problem is, try to fix the junk, or try to find good designs without a large outlay of cash!..

 

[PILOON]

Some years back I owned an aviation facility that did lots of avionics installations.
Let me tell U it got rather hairy at times.
A common installation for us was HF communication radios.
Crazy things could happen.
Transmit on 4182 (ex) and the helicopter main rotor indicator could show a crazy RPM like 12 rpm.(should be ,ex 600)
Or another frequency might say your engine just quit,
Now with HF (AM and SSB) which is 2-30 Mhz those tests too literally days to really complete.oing tests to chart EMI/RFI interference soon became more costly than the physical installation.
It also required a certified mechanic that could run that machine on the ground.
OK, I got smart and simply placarded like. at 3i50 hz main rotor will read erroneous.

All to say,EMI/RFI can be a real problem.

If it simply affects your radio you are still in the safety zone.
To comply with all the regulations became so costly that clients balked.