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

[PILOON]

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

My radio is a retired automobile AM/FM and I have stereo speaker behind mt operators station.
I will add that all my antenna lead in is shielded so that might help.
The only EMI/RFI issue I have is that I do hear the click/click from my home made strobe light which is actually 3 12 volt halogen bulbs that I flash with a standard flasher unit with a load resister for loading. And at that it is minimal.

I might be that as a retired Avionics technician that I used standard aviation techniques in my installations.
Like, shielding, bonding sound bonding etc.
Aircraft are very critical platforms for radios and nav aids.
AKA, I've seen it all!

 

[W8BYA]

Thanks for the update, and for all your efforts!

You are most welcome. I am not stopping this study.....I will continue looking for an inexpensive commercially available filter that others will be able to use.

 

[W8BYA]

You be the judge, W8BYA, but I propose to push this further off in an entirely different direction...lol, but it IS related to LED lighting on tractors.

My Terramite T7 came with an amber beacon on the roof. The original (strobe based, talk about RFI) died, and I decided to replace it with one of the cheap, LED based offerings. Long story short, I went through 3, made by 2 manufacturers. All of them died within the first few hours of use. The failure mode was the destruction of the driver chip. After the second one, I measured ambient and running voltages on the machine, and all was nominal. Tops was about 13.9VDC running with a fully charged battery. I figured I had settled on a poorly designed unit that couldn't handle a high duty cycle in the Texas heat, and recently got a unit from Tractor Supply that is a re-design of an un-impressive one they sold a few years ago. I installed it, and it worked great till the second time I started the machine, and now it's dead. If I take it apart I am expecting to find another cratered driver.

The light bulb (the one in my head) finally went on. I am probably looking at starting motor generated transients, and I need to install something on the B+ line, or in line with the strobe to protect it from such events. I am currently deciding what specifically to use. I don't have a number for a suitable MOV or module or coil, and I'm wondering if anything comes to mind for the purpose. The strobe is wired to go on with the ignition, and I want to keep it that way (i.e., no switch).

I love my Terramite, but they sure don't have any parts installed in them that are not absolutely necessary, and apparently, some kind of electrical system surge suppressor is on that list. Now that I think about it, I don't even know if cars have a discreet component that fulfills that mission. Anybody have any ideas?

I can sympathize with your strobe issue. I think it would make a great new thread. Seriously go ahead and start one up, I'll bet you will get a lot of other folks with similar issues. I would like to keep this one on target, as much as possible anyway. As many have already noted we have managed to rack up a lot of pages, and some of them not really related <g>.

Anyway, without throwing an oscilloscope across the power lines near where the lights would go I really would not feel right just shooting from the hip. But if forced into a corner where I had to spit something out in 5 seconds I would suggest trying a simple L-network on the positive power lead. Take the +13.8VDC line and pass it through something like a 0.5 mH inductor then to an electrolytic capacitor from the + line to chassis ground. The cap might have a value like 5,000 uF rated for 50 VDC operation.

Absolutely no promises on the suggestion, not w/o some idea of what you are really trying to keep out of the flasher electronics. But please do start a new thread and I will be happy to join you there. GL

 

[W8BYA]

My radio is a retired automobile AM/FM and I have stereo speaker behind mt operators station.
I will add that all my antenna lead in is shielded so that might help.
The only EMI/RFI issue I have is that I do hear the click/click from my home made strobe light which is actually 3 12 volt halogen bulbs that I flash with a standard flasher unit with a load resister for loading. And at that it is minimal.

I might be that as a retired Avionics technician that I used standard aviation techniques in my installations.
Like, shielding, bonding sound bonding etc.
Aircraft are very critical platforms for radios and nav aids.
AKA, I've seen it all!

Yup you are absolutely right. Proper bonding and shielding are a vital part of a sound engineering approach. But don't forget filtering. I have already determined & noted that my particular issue is due to massive RFI in the form of conducted emissions on the DC power lines being generated by the switch mode power supply in the LED light fixture.

In my case that corrupted DC power is making it's way directly into my AM/FM radio. I can completely disconnect the antenna from the radio and still have a wiped out receiver. RFI can come in the form of radiated or conducted emissions or a combination of both.

There are some radiated emissions that I can detect but the vast amount of RFI is getting into the radio via the power lines. Also the coaxial line that connects the antenna to the radio is properly shielded and terminated at both ends. Thank you for your suggestions.

 

[radios1]

I remember when I built my WWVB receiver I had to use metal cased tantalum capacitors to keep out RF from the receiver power lines, no other capacitor type would work.. I didn't try SMD chip capacitors though.. they may have worked. also, did you put your filter as close as possible to the lights, so that you don't have RF along the wires?.

 

[W8BYA]

I remember when I built my WWVB receiver I had to use metal cased tantalum capacitors to keep out RF from the receiver power lines, no other capacitor type would work.. I didn't try SMD chip capacitors though.. they may have worked. also, did you put your filter as close as possible to the lights, so that you don't have RF along the wires?.

Tantalum caps are very common because of their dielectric (they provide a lot of capacitance for their small size) but they tend not to hold up well in hostile environments. We tended not to use them in military hardware because they had a high failure rate vs. time. Your idea of chip caps are spot on....they are generally excellent for RF applications and usually very stable over time (but it depends on brand, model, etc). Another good choice for RF bypassing and filtering, believe it or not, are Silver-Mica caps, like the ones made by CD. For high values believe it or not a good quality Sprague etc Electrolytic cap can be hard to beat.

Some time ago for giggles I tested on a VNA how the capacitance of a capacitor changes with frequency. A lot of folks think when they shunt or bypass a DC line with, say, a 10 uF cap, that it will be 10 uF from DC to daylight. That is not always true. I was even testing expensive RF chip caps made for transmitting applications and saw changes starting even down at low frequencies.

I did this as I was designing a LPF for a 1 kW RF amplifier for our 6m amatuer band and the prototype I built did not match the predicted performance curves I was expecting based on modeling. Anyway, some tests on the VNA showed my why.....it was fascinating and eye opening, even to an RF engineer. Not all caps are made the same. Lets see if I can get a plot below of several caps I tested that show the fall off of capacitance as the frequency is increased. Believe it or not (SOME) Silver Mica caps were better then very expensive chip caps made for transmitting applications.