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I'm 20 years removed from radio work but this doesn't sound like RF. Ground issue maybe but otherwise stumped. If you mean the cab radio, there are two electrical systems in the RV with the radio fed by one and if I am understanding you lighting is house side, that is on another. The grounds are common but that doesn't mean they aren't an issue and ground loops can do strange things. AM good? Ant ground? I repaired car radios but dislike them. Hateful little devices.

Edit: This kind of question is the stuff that keeps me laying awake at night. (I kid). A quick (or not so) rational. It's a cheap power supply for a led light. What range do you think it operates in? It is not going to be high freq as they wouldn't want the added cost for components rated for it or the added complexity. FM is 66 to 108 MHz. and even IF is 10.7. Even if I was willing to calculate out complimentary frequencies, I just can't see some light putting out enough broadband RF as to kill the entire FM band. Make sense? Every station? Some strange ground related noise..maybe..who knows...kinda sounds like a crap shoot. I don't know what you've got installed, how it is installed and how tight your DC electrical system is. Maybe you popped the radio in the dash and are counting on a iffy antenna ground and didn't bond the black ground wire at all. Maybe you did and even used the little metal strap that came with the radio to secure it and it is in better than I could have done. Still a bunch of unknowns but still not sure why you are convinced it is RF or IF. You said you tried caps. On the power? Try a little bit of L with the C. Makes a better noise filter. They used to make LC filters in little cans for Alternator whine. I've no idea what to suggest for EMI, RFI or what ever kind of noise this led light power supply of indeterminate design and manufacture is crapping out.

I am publicly on record in this post as stating I dislike radio. Radio is dead to me (and a dying platform for many). This is just one more reason added to my list.

This seems to be an issue with these particular LED's I have two other friends with them and they have the same problem unfortunately I was the one that told them about the light's! It is a shame they are very will built bright flush mount lights. It is a switching supply and they are noisy if not well built. I have a friend that is an RF consultant (people call him Mr. Intermod) I may just take one to his shop.

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This seems to be an issue with these particular LED's I have two other friends with them and they have the same problem unfortunately I was the one that told them about the light's! It is a shame they are very will built bright flush mount lights. It is a switching supply and they are noisy if not well built. I have a friend that is an RF consultant (people call him Mr. Intermod) I may just take one to his shop.

It's a led light. Low voltage, low current at the led itself. You seem sharp enough to figure out how to perhaps modify/bypass it for normal 12 DC operation. Just don't tell me there is a dimmer with this.

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I do ham radio AM even up into the 6 meter band (50 MHZ) it has nice audio because of its band width but it is prone to noise and static crashes so it's not something I use on a regular basis. I used to love AM as a kid playing with crystal sets and DX with better radios when it was quiet at night listening to the clear channel stations like WOWO and WBAL. Now my listening is sat. radio (works everywhere) 900+ channels something for everybody no adds every 5 mins. and FM radio for local news/weather.

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It's a led light. Low voltage, low current at the led itself. You seem sharp enough to figure out how to perhaps modify/bypass it for normal 12 DC operation. Just don't tell me there is a dimmer with this.

No dimmer but it's a wide voltage lamp up to 30 volts. The supply output is 10 volts I had toyed with the ideal of a 12 volt LM 7812 and a couple other dodads on the lighting circuit powering all on that home run and scrapping the switching supply.

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No dimmer but it's a wide voltage lamp up to 30 volts. The supply output is 10 volts I had toyed with the ideal of a 12 volt LM 7812 and a couple other dodads on the lighting circuit powering all on that home run and scrapping the switching supply.

Quick idea. Disconnect supply and connect some value of resistor equal to the load of the led and turn on (aprox 1k @ 12v for 10mA halve for every doubling). It will isolate the supply from the light. At least you'll know which end is giving you fits.

More info than you'll likely want but have a look here Somewhere within this thing is likely some of the devices listed there built into that light. Otherwise beyond my ability to discern over the web.

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Something else to play with, if you need some cheap computing power

http://makezine.com/2015/05/07/next-thing-co-releases-worlds-first-9-computer/

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I'm platform agnostic in that I do not care what the anyone else uses. I often wonder though, is Linus Torvalds so angry because he's had to use Linux for 20 years? Sometimes I picture him sitting alone in a dark locked room, pulling a macbook from under his bed and weeping in the glow from the screen.

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Quick idea. Disconnect supply and connect some value of resistor equal to the load of the led and turn on (aprox 1k @ 12v for 10mA halve for every doubling). It will isolate the supply from the light. At least you'll know which end is giving you fits.

More info than you'll likely want but have a look here Somewhere within this thing is likely some of the devices listed there built into that light. Otherwise beyond my ability to discern over the web.

Yeah I have had these things apart they are switch mode that's a nice site good stuff there.

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Yeah I have had these things apart they are switch mode that's a nice site good stuff there.

A couple of things first before I eat my hat. Did you at least do any cursory searches on the web on this subject? I'm on vacation this week, I'm supposed to be allowed to be lazy.

So sure, I did a bit of poking around. Cheap device, cheap electronics, loads of RFI noise. Manufacturers make no attempt to mitigate due to cost of producing a better product. You said this was an under the counter light? MR16 type bulb perhaps? Just amuse me and open a blank web page and go do a google search for "led lights interfering with radio reception". From the little I read, its a bit all over the map. Some are transformer issues other strange power anomalies. I've been working with and using pulse width modulating power supplies for a long time. Never any issues. Probably because I don't buy cheap crap.

Here, start with this. Seemed like the best treatise on the subject at least within my limited search. Just please don't ask me how to fix it. Just get a different bulb and retro it in the fixture and call it a day. Now I really hate radio. Where is that salt. I'll be in the kitchen figuring the best way to cook hat.

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It wipes out the receiver no real noise just kills the receiver front end to the point it's all most like the antenna was unplugged. I don't know what the freq is the counter will not pick it up. It's mixing with some thing in the FM band and the IF but like I say the sat stuff is way out of it's range so I still have my tunes!

Ok, I've been able to sleep on what little I've read and have put together a speculative connect the dots opinion of what I think is going on. I have partial information on a couple things and basically no information on the rest so no chance I can mess this up right?

The last link I posted seems to have one thing in common. Most of these bulb types are legacy bi-pin halogen's where many of the LED bulbs were designed to replace them. A lot of the fixtures were the old low voltage transformer types. Hence AC. The LED's that came out to replace those were designed to work without loading the transformer and have minimal current draw hence the higher freq pulse mode supply. Good ones worked ok if anyone bothered to consider RF. This part is pretty well documented and I can point to a few reputable resources to back this part up. Starting with this fact sheet

From here on out, total speculation. LED's have become popular sellers and now enter cheap knock offs. Problems begin with the above type bulbs prompting even regulatory bodies to write papers on it. These papers address the issue from the original design aspect, mainly installation of the bulb in a transformer fixture. I would speculate that the light fixture you have has no transformer. So why would it have such a bulb? I think some manufacturer had these bulbs available cheaply and rough shod a quick power supply to drive it, packaged it in a fixture then some guy installed it in his RV killing his radio whenever he turns on the light. I'm speculating the issue isn't with the power supply feeding the fixture but the electronics built into the bulb itself. If the bulb itself is not removable, your only recourse might be to junk the light. You can confirm this for yourself by simply doing the troubleshooting I suggested by putting a load on the external power supply for the fixture and running it without the LED lamp. If it doesn't kill your radio, it is the bulb itself.

When I retro fitted the RV to LED, I used bulbs meant to work with 12 volts using the existing fixture. There are plenty of bulbs out there. Unlike the bulbs you buy designed to plug into you household fixtures that run on AC, these have no need for all the electronics. LED's are a DC device, need very little current and work fine off the RV battery with minimal current regulation and a bit of diode protection. My thought was why the hell would a LED need a high freq PM supply? It certainly doesn't in your RV.

My advice still stands. Get a bulb intended to work directly with 12 volts and retro it in the fixture. If the bulb is a cheap knock off of the type listed in the link I posted, you are not likely to fix it short of wrapping it in grounded foil but then you'd get no light from it.

I started this post to show people how to make use of the RV battery for powering common every day items. I want to clearly let everyone know that your problem is an anomaly and not the norm with power supplies. The little buck converters I use run at very low frequencies and do not create any of the issues you are having. There is nothing inherently wrong with switching power supplies.

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When I retro fitted the RV to LED, I used bulbs meant to work with 12 volts using the existing fixture. There are plenty of bulbs out there. Unlike the bulbs you buy designed to plug into you household fixtures that run on AC, these have no need for all the electronics.

My advice still stands. Get a bulb intended to work directly with 12 volts and retro it in the fixture.

I started this post to show people how to make use of the RV battery for powering common every day items.

There are many 12 volt DC LCDs that also can give some interference with the FM band. Seems they all have built-in power supplies, regardless if meant for 120 VAC input or 12-14 volts DC input. I've got a whole cabin full of 12 volt DC lights (off grid solar) and only had a few slight problems. Kind of a crap shoot. Buy the bulb and try it. More on the AM band then FM for me. But yes, 120 volt AC to 12 volts DC conversion in some uses can wipe our fringe (weak) radio reception - regardless if in a LED light-bulb/power supply or just built into a radio itself. I spent many years participating in a few fringe-reception forums (for TV and radio) and bought some radios touted as having the best reception. One - targetted at the AM band is my Katio KA1103. In the weakest signal areas - it pulls in channels very well when on battery power, but if I plug it in to an AC outlet to power it - I lose those weak channels. Same with my Grundig (which is really a Tescun BCL-2000).

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OK these are designed for RV's and sold as such the LED is not a plug in and has no electronics of it's own.For what these lights are they were quite cheap and it kind of leads me to believe one of two things. They quit selling them because of the noise or the FCC told them not to as I say I'm not the only one that has had noise issues with them. I have fixtures that in their former life were 10 watt halogens those work fine with a G4 base LED. I know part of the issue is the radio it's self there has been little or no real effort to reduce noise and in a modern car that really is not much of an issue but not so in a camper with added electronics. This thing does not like any type of PWM my PWM controller for my portable solar sounds like a motor boat! I agree the modern switchers are usually fairly quiet i have several running and it does not bother my ham gear.

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OK these are designed for RV's and sold as such the LED is not a plug in and has no electronics of it's own.

I'm not saying they don't exist, but I've yet to come across an LED for lighting purposes that does not have some sort of power-supply or regulator on board. Even my new 12 volt LED marker and clearance lights have circuit boards with little goodies on them.

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I'm not saying they don't exist, but I've yet to come across an LED for lighting purposes that does not have some sort of power-supply or regulator on board. Even my new 12 volt LED marker and clearance lights have circuit boards with little goodies on them.

A regulator is one thing. Active current limiting and polarity protection is not inherently noisy. The only reason I can speculate that makes sense to have anywhere near the high freq that gets into the FM band is bragging rights or to produce some near white band of light. Everyone seems to want to claim the lowest power consumption. Maybe that. Again, I keep saying that I am speculating and 20 years removed from radio anything except for wireless microphones perhaps. What I do for a living these days is not anywhere remotely related. I'm just some moron behind a keyboard.

I'm pulling out to go head to the beach even though the weather is supposed to be crappy over the next couple days. Hoping to at least get a hint of sun sometime within the next couple days. This is going to be the first trip in almost 3 years. Had a couple trips this summer that has gotten cancelled due to family circumstances. Even today we have to stop off on our way to deal with issues with my wife's mom. I hope we make it to the Cape. If I post later tonight, you'll know things did not go well. Mom is not transitioning well in the care facility. Thanks for the distractions guys.

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I'm not saying they don't exist, but I've yet to come across an LED for lighting purposes that does not have some sort of power-supply or regulator on board. Even my new 12 volt LED marker and clearance lights have circuit boards with little goodies on them.

Yeah they all do usually have a small chip in the led board. The ones I have has an external board feeding the LED's.

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A regulator is one thing. Active current limiting and polarity protection is not inherently noisy. The only reason I can speculate that makes sense to have anywhere near the high freq that gets into the FM band is bragging rights or to produce some near white band of light. Everyone seems to want to claim the lowest power consumption. Maybe that. Again, I keep saying that I am speculating and 20 years removed from radio anything except for wireless microphones perhaps. What I do for a living these days is not anywhere remotely related. I'm just some moron behind a keyboard.

I'm pulling out to go head to the beach even though the weather is supposed to be crappy over the next couple days. Hoping to at least get a hint of sun sometime within the next couple days. This is going to be the first trip in almost 3 years. Had a couple trips this summer that has gotten cancelled due to family circumstances. Even today we have to stop off on our way to deal with issues with my wife's mom. I hope we make it to the Cape. If I post later tonight, you'll know things did not go well. Mom is not transitioning well in the care facility. Thanks for the distractions guys.

Have fun on your trip. Little update it is definitely RF I carried a portable receiver out to the camper it does the same thing even standing outside.

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Cowboy RF noise trouble shooting, Get the cheapest old fashion AM portable radio and just hold it near possible noise sources. You can tell real soon where the problem is.

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Yeah it works great in some cases we have used them for power line noise when you think you have honed in on the noise grab the guy line and shake the pole!

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Yeah they all do usually have a small chip in the led board. The ones I have has an external board feeding the LED's.

Most LED's require a little under 1.5 volts to overcome the PN junction. The D after all still stands for diode. The newer high output LED's can have up to a 3.3 volt forward bias requirement. So driving them is not so much an issue till you start to get into arraying them. In its base circuit all a LED needs is a current source (battery) and some sort of current limiting device. Typically for use as an indicator it has simply been a resistor. So current + LED + resistor = light. Most bulbs however are arrays of series, parallel or series-parallel arrangements of LED's. The design choice balances simplicity and reliability along with cost. If many LED's are connected in series, then there is a need for higher voltage. Cost savings are realized connecting in series as only one current regulator circuit is needed. This is the only reason for a switch mode supply to drive LED's as now your array needs far more voltage than the 12 volts the RV is supplying. The current regulation regardless if IC or just some resistors will have no noise issue. All the reading I've done suggests the problems is with cheaply designed power circuits that are minimally spec'd to just work with no consideration for RF. The FCC isn't hunting any of these manufacturers down and fining them so no incentive to change that.

A couple of the more hard core ham guys have dissected more than a few such offending bulbs. Most of these are designed for AC use and hence more complex power supply and regulation. Their experience has been that many of these cheap offending bulbs have no filtration at the drive coil and as such the ringing of the pulse is creating all sorts of noise. A few have added small value Caps between the drive voltage and ground and have effectively stopped the noise or at least got it down to the point where they could operate their radios. Here the ability to do the math is helpful in figuring what value is needed for the frequency range. The coil is not going to be very high Q so a filter cap is not going to be narrow in band which is this case would be good.

I've got some of the cheapest 1156 bulbs I could find in my RV and while camping this week I turned on the radio while I had all the lights a blazing. No problems. Pretty sure given the size of these things, I am not going to find a switch mode supply inside with an offending coil. I'll take one apart later this weekend and figure out what it is using for current limiting.

All in all, it is very much a crap shoot as to what you'll get and little way to know in advance of purchasing it seems. I don't listen to radio nor am I a ham operator so I've little skin in this game. AM radio? I don't even want to go there. I can rub my hands together and create enough static electricity to mess up the reception. (only pity will be taken upon anyone who read this last comment as anything serious)

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My fix is simple I just turn out the light but it drives me nuts only because it shouldn't make noise and often the light is helpful in the dark! So for my next trick one of them gets to come inside and get hooked up to the scope I think this is going to produce a brilliant image of a bunch of spikes. I tried a by pass cap on one it was not impressed. Most of the multi diode boards have small chip regulators plastered right on the board these things have wires between the input and output and the supply is fair size, wires make pretty good antennas. The other 7 G4 base and one tower bulb LED's cause no problems.

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Not sure the size Cap you tried but something around 100nF across both input and output side of the power supply might help (big guess on the inductance with a target range up to 200MHz). I build magnetic instrument pickups and use copper foil tape and ground them to shield from noise. Have you considered putting the power supply in something similar? I serviced plenty of radio's that had switching supplies. Some were shielded others just had good RF filtering built in. Should be able to do one or both to this simple little lamp supply.

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If there is anybody who can derail a topic better than us, I've not met them yet. This started as the, hey it's kind of cool how I made all those odd little niceties for the RV work off the battery and turned it into this. I guess its what we do.

So here is what I am talking about. A LED in an RV that doesn't need to be a million candle power shouldn't need any sort of switching power supply. Like I said, I purchased the cheapest thing I could get off of Amazon. At $2 each, let me introduce you to the little champ now.

lamp_01.jpg

It's the little 1156 that could. At this cost, my guess is that underneath that handsome exterior, lies a simple little current limiting circuit. (I know, no fair, I already peeked) So what did I find?

Just what I guessed. 18 LED's in a parallels series circuit of 3 LED's in series on little pc boards all connected (6 in all) in parallel. Current regulation? Two resistors. One 24 ohm the other 120. It is a 12 volt system. It is unlikely to suddenly be 50 volts. Current regulation is inherent in the way the device works and what it is connected to. I know from recent reading that there are some RF issues out there. What I don't understand is for this application, why?

It spilled its guts and so the early demise of one little cheap lamp all to satisfy my endless curiosity.

lamp_02.jpg

Oh and I forgot to mention. The only thing radiating out of these lamps are light waves. I just didn't want our discussion to give people the idea that if they go out an update their lighting that they would be killing there ability to receive radio signals. That doesn't necessarily have to be the case and my point is if you simply swap out the incandescent bulb in the original fixtures, you'll probably not have any issues. The main complaint I see about LED bulbs is the color temperature is not what people are expecting. In this case these are cool white (approx) but the slightly yellow nature of the lamp cover makes the output fairly warm. They have plenty of light but seem a bit less so than the regular bulb.

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Well it's still on topic it's RV 12 volt stuff. Any way the ones I bought are gone the only flush mount led's are in the $50-$100 range now on ebay. The LED fixture supply is a nice sawtooth at 240 KC. So it’s on and off 240,000 times a second. I can see no reason why that is needed unless the voltage in is very broad I’m betting like 6 to 30 volts (boats and other stuff with 24 volt systems) so I think something in the 30 ohm range will bring the LED voltage to around 10 volts at 12.7 or I could use a biased regulator to keep it at 10 volts, that maybe the way to go. The led board is just led's nothing else with a aluminum back against the fixture shell so it would be no problem to just remove the power supply and use a regulator.I guess other than it was driving me crazy there maybe others having the same issue with other lights and I would recommend that they not buy a broad voltage range led lighting fixture but some thing designed for the 12 volt range only.

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My friend put a set of the color changing strip LED lights on his boat. The control unit interferes with the radio sound by creating lots of noise. Its not the LEDs themselves that are making the racket.

I believe that is what all the discussion was about. Seems to be a lack of thought regarding RF in the design of cheap light fixture power supplies and a regulatory agency of a government that would prefer the energy savings over the integrity of functional bandwidth. It is not like you are taking out the neighborhood with them so the wound is only self inflicted.

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Well it's still on topic it's RV 12 volt stuff. Any way the ones I bought are gone the only flush mount led's are in the $50-$100 range now on ebay. The LED fixture supply is a nice sawtooth at 240 KC. So it’s on and off 240,000 times a second. I can see no reason why that is needed unless the voltage in is very broad I’m betting like 6 to 30 volts (boats and other stuff with 24 volt systems) so I think something in the 30 ohm range will bring the LED voltage to around 10 volts at 12.7 or I could use a biased regulator to keep it at 10 volts, that maybe the way to go. The led board is just led's nothing else with a aluminum back against the fixture shell so it would be no problem to just remove the power supply and use a regulator.I guess other than it was driving me crazy there maybe others having the same issue with other lights and I would recommend that they not buy a broad voltage range led lighting fixture but some thing designed for the 12 volt range only.

8 days into this conversation and I have to admit I'm still not sure what it is that you are looking for. I have some sense of what it is you have from a functional perspective. A flush mount LED. Based on the limited description of the product you gave, it is likely a fixture that has a limited number of actual LED lamps and they are likely of high wattage type using the fixture as heat sink, say 3 or 5 watt or perhaps a few 1 watt. This would be why it has that infernal supply. It is likely more for constant current regulation rather than voltage. So you can put the voltage regulator in to dial it down to 10 volts but you still need to limit the current. A single 5 watt bulb means you would be pushing a decent amount of current through that resistor. The calculus is how many bulbs at how many watts for current draw at 3.3 volts per LED. Add it up and figure out the voltage drop across that resistor. Multiply the voltage and current and that is the wattage size of resistor you will need. It could be pretty big wattage and throw off a fair amount of wasted energy as heat.. I don't like any of it as a solution and will stick with my super simple little bulbs.

Did you consider at all my suggestion to shield the power supply? I mean what have you got to lose? A bit of foil and a clipped lead to ground.

I will repeat. I went the super simple route (also cheap). I only changed one fixture in the RV. It's lovely and cost $16 It's a wall sconce that also takes a standard automotive bulb and I installed the cheapest LED bulb in it I could get. Works great. No noise.

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Caps,shielding had no effect. The LED is about a watt and a half 23 chips.The fixtures were under $9 I should have taken a photo when I had one out they seem to no longer exist. The tinkering the other day produced a smoked power supply it now sports a 12 volt 15 chip board that I had. The others are going to get their own regulator I only have 6 to do. It's sort of a stupid thing but the gallant has been thrown down.

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My friend put a set of the color changing strip LED lights on his boat. The control unit interferes with the radio sound by creating lots of noise. Its not the LEDs themselves that are making the racket.

Yes an LED in its self produces no noise it is nothing but a diode. it's when they make them do tricks the problems arise.

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Oh yeah, with out a spell checker no one would have a clue as to what I was trying to say so most any spelling looks good to me!

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