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06-15-2019, 05:30 PM
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Join Date: Dec 2005
Posts: 182
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Noise From Strobe System
I recently installed an LED strobe system, and I'm getting some radio noise. It sounds like "ssit-ssit-ssit-sist" each time the wingtip strobes flash (they flash in sync). The manufacturer suggested a 10uf capacitor be installed from the output of the switch to ground. That didn't help. The noise only occurs when there is an incoming transmission - it does not occur continuously when the strobes are on. For example, if I'm monitoring ATC, the noise only occurs when a transmission from ATC is received. Just wanted to know if anyone else has had a similar problem and found a solution.
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06-15-2019, 08:04 PM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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Only hearing the noise when the radio is receiving is a clue. Try opening the squelch on the radio & see if you hear it continuously. If so, that's a hint that the noise is getting in through the radio, but you still don't know if it's RF (being picked up by the antenna) or riding a ground into the radio's power supply.
Unfortunately, there's no universal cure; just some things to try.
Easiest 1st would be ensuring that the radio's antenna coax shield has high quality continuity from the radio all the way to the antenna, and the antenna ground has a good bond to the airframe.
Next would be trying the recommended filter, but at the LED module terminal(s) instead of the switch. In other words, a filter on each module.
Next would be the LED modules' ground paths. If the filters don't solve it, try a temporary ground wire (obviously, while the plane is on the ground) from each module back to the 'forest of tabs' near the battery. In other words, lift all the LEDs' local airframe grounds & run the grounds direct to the battery negative.
All the above are ways to chase ground path noise. If the LED modules are indeed radiating RF energy into the radio's antenna, that's going to be much harder to address.
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06-16-2019, 05:27 AM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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Are the strobes a single unit or are the 'power supplies' separate from the light assy?
Earlier in LED strobe development, RF broadcast noise was a common issue. If the power supply is separate, you can try building a Faraday cage around it. This is simply enclosing the power supply in metal that is grounded to the airframe.
I had similar issue with HID power supplies. I wrapped them in aluminum foil and grounded to the airframe. Noise gone.
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06-16-2019, 05:28 AM
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Join Date: Dec 2005
Posts: 182
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Those are good thoughts, thanks!
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06-16-2019, 06:43 AM
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Join Date: Mar 2009
Location: Plano, TX
Posts: 2,090
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What brand strobes are they? Im not asking as a dig at the vendor, but for comparison purposes for others with the same brand. For example, I have aveo powerburst lights. They are using an airframe ground at the outboard wing rib. All power wires are run separate from all comm wires. I also have cheap automotive HID lights. I have no noise issues.
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Complete 5/10/19
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06-16-2019, 07:24 AM
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Moderator, Asst. Line Boy
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Join Date: Jan 2010
Location: Flower Mound, TX
Posts: 1,473
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VAF Search is your friend
Terry,
Over the last decade, several quite-useful VAF threads have discussed this problem. Do a VAF search of threat titles using the words "LED noise" and simply "noise", kick back, and read the wisdom.
Sounds like you might benefit from the technique of grounding the LED power wire shielding at one end. That worked for my 7A ( older AeroLED wingtip and tail lights...their newer models have virtually no noise). The VAF search will give you good info. In addition, check this out:
https://www.experimentalaircraft.inf...wer-ground.php
Hope these help.
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52F NW Regional/Aero Valley Airport, Roanoke TX (home of DR's Van Cave)
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06-16-2019, 08:06 PM
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Join Date: Dec 2005
Posts: 182
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The lighting system comes from AvioLights, a company in Poland that makes lighting systems for aircraft in Europe. http://aviolights.com/ The LEDs and their power supply are molded together in the light assembly itself. They have been open and supportive about trying to find a solution for the noise I'm experiencing. A complicating factor may be that I removed a Whelen system to install the LED system, and adapted the wiring used for the Whelen strobes. That may be part of the problem, so I'll need to review the wiring in more detail to see if there is anything I should do differently. I did do a search here for additional threads on this subject, and I'm still wading through all the commentary. Thanks in advance for your many suggestions - they are much appreciated.
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06-16-2019, 08:38 PM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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There's a method to completely eliminate noise in switching regulators for LED landing lights using an additional adjustable DC/DC converter.
This was verified with a spectrum analyzer. As the LEDs were driven with the typical 13.8V supply the noise radiated back into the the supply. This noise or distortion is sort of like turning the volume up too high on your stereo.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Adjust for maximum brightness, minimum noise.
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Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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06-16-2019, 10:46 PM
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Join Date: Aug 2010
Location: Out West!
Posts: 80
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Unrelated to the thread but Bob, your inbox is full trying send a message about XCOM radios.
Drop me a PM with some contact info!
Back to your normally scheduled programing.
Quote:
Originally Posted by rocketbob
There's a method to completely eliminate noise in switching regulators for LED landing lights using an additional adjustable DC/DC converter.
This was verified with a spectrum analyzer. As the LEDs were driven with the typical 13.8V supply the noise radiated back into the the supply. This noise or distortion is sort of like turning the volume up too high on your stereo.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Adjust for maximum brightness, minimum noise.
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06-17-2019, 06:52 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Quote:
Originally Posted by Pave Tim
Unrelated to the thread but Bob, your inbox is full trying send a message about XCOM radios.
Drop me a PM with some contact info!
Back to your normally scheduled programing.
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email me rocketbob at gmail com
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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