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  #1  
Old 08-06-2019, 06:09 AM
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dromuald dromuald is offline
 
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Default LED RF noise

I recently installed some "Offroadtwon" LED lights into my leading edge landing and taxi lite openings. I replaced some HID lights because they were not working with the wig wag module I purchased. The lights work great and are certainly suitable from an illumination standpoint. However when I turn them on I get continuous static that is quite loud in my headset when I have my radio on. Without the radio on I get about a one second burst of static when I switch the lite on, then it goes away. I did not have any noise from the HIDs so I suspect it is from the lites themselves. I do have a local ground on them, but it is about 2.5 feet long.
I spoke with others who suggested replacing the LEDs with Baja Sqd Pro lamps. My primary use of the lamps is for collision avoidance using the wig wag function. Since I really don't plan on flying much at night I was not planning on spending hundreds of dollars on LEDs. Looking for advice on a few questions.

1. I am going to try shortening the ground wires and ferrite beads, but would I be wasting my time since it is likely internal to the LED and not the wiring that worked fine with the HIDs?

2. Are there any other solutions I might try with these lamps.

3. Has anyone tried the Baja sqd SPORT LEDs? They are about half the cost of the Pro version and would certainly serve my purpose.

Thanks in advance
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  #2  
Old 08-06-2019, 06:26 AM
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Brantel Brantel is offline
 
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It’s likely a noisy constant current driver inside the light.

Many moons ago I worked with Bob Knuckles to develop a filter for similar issues and he was selling them at one time.

I would call him and see if he is still making them available.

Another option is to rip the CC driver out of the lights and replace them with a current limiting resistor that will produce zero noise.
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Last edited by Brantel : 08-06-2019 at 06:28 AM.
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  #3  
Old 08-06-2019, 06:28 AM
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maniago maniago is offline
 
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Quote:
Originally Posted by dromuald View Post

1. I am going to try shortening the ground wires and ferrite beads, but would I be wasting my time since it is likely internal to the LED and not the wiring that worked fine with the HIDs?

2. Are there any other solutions I might try with these lamps.

3. Has anyone tried the Baja sqd SPORT LEDs? They are about half the cost of the Pro version and would certainly serve my purpose.

Thanks in advance
Your LEDs have a DC-DC current limiter - basically a switching power regulator, and is your EMI source. Not all LEDs use this chip. Run the power and gnd lines as a twisted pair all the way back to your gnd block and maybe try some Chokes as well. Both solutions are cheaper than replacing the lights. May not work, but worth a shot...example solution https://www.youtube.com/watch?v=MGtQR7mr-F0

Here's a quick read on whats going on with some LED lights for anyone not sure about how these work. https://e2e.ti.com/blogs_/b/behind_t...e-led-lighting
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Last edited by maniago : 08-06-2019 at 06:48 AM.
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  #4  
Old 08-06-2019, 06:42 AM
BillL BillL is offline
 
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I have the Baja Quad Sport, the smaller 3" or so dimension. They are absolutely quiet RF wise.
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  #5  
Old 08-06-2019, 06:53 AM
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dromuald dromuald is offline
 
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thanks Brian, I believe they are sealed units and ripping out the cc sounds complicated. However can you supply me with Bob's contact info. I am willing to try the filter if it still available or I could build one.
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Old 08-06-2019, 06:53 AM
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dromuald dromuald is offline
 
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Thanks Bill
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  #7  
Old 08-06-2019, 07:00 AM
Timberwolf Timberwolf is offline
 
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You said shorten the ground.....are you using the airframe as a ground at the light? If so it needs to be run all the way back to one central grounding point. Thereís LEDís on amazon around $30 that fit in PAR36 housings and are silent, not to mention put out an amazing amount of light. Perhaps the easiest solution would be to swap to a known unit that produces no noise.
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  #8  
Old 08-06-2019, 07:17 AM
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dromuald dromuald is offline
 
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thanks Shane;
I am grounding to the airframe. The only central ground that I know of would be back under the instrument panel which would be a pain to run a wire to. Do you have any verified LED options that are noise free? Or what would I look for to find them?
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  #9  
Old 08-06-2019, 07:32 AM
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Quote:
Originally Posted by dromuald View Post
thanks Brian, I believe they are sealed units and ripping out the cc sounds complicated. However can you supply me with Bob's contact info. I am willing to try the filter if it still available or I could build one.
http://www.aeroelectric.com/

The more I think about it, I just remembered that the device Bob was selling also included the driver on the board in addition to the filter which is not what you will need.

Here is the documentation for the product he was selling, it includes the schematic and the filter components listed so you could use it as a basis for designing a filter that would fit your needs....that is if you can gain access to both sides of the built in CC driver. If not, you might contact Bob for some advice on a filter design that would work well for just filtering the power input to the lights.

https://web.archive.org/web/20101217.../9051-700A.pdf
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Last edited by Brantel : 08-06-2019 at 07:42 AM.
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  #10  
Old 08-06-2019, 08:37 AM
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M McGraw M McGraw is offline
 
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I had noise from all my LEDs strobes, landing, taxi, wig-wag. It took a while but I did find the culprit. All my headset connections were properly insulated; however, the picture below was the culprit and fix. I had a metal push to talk on the right side of the panel. I replaced it with the plastic one from McMaster-Carr.
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