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  #1  
Old 01-15-2012, 04:38 PM
BillFear BillFear is offline
 
Join Date: Oct 2007
Location: Sherrills Ford, NC (Lake norman area)
Posts: 432
Default Help with MR-16 LED lights

Decided to buy a couple inexpensive 12volt LED MR16s (3x3watt crees) to replace my 75watt halogens in the wingtips now that we have added Duckworks HIDs for the real landing lights.

Love the light they make and the low power usage but as expected the drivers interfere with the radios big time. Anyone have any success building a noise filter that will work with the noisy driver that comes in these lights??

Any input would be appreciated.
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  #2  
Old 01-15-2012, 05:25 PM
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rocketbob rocketbob is offline
 
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Location: 8I3
Posts: 3,759
Default

Bill you must have finally gotten those lights.

Basically large fluctuations of current turn the supply wire into an antenna transmitting a bunch of high frequency noise.

Shielded twisted pair supply wire, don't ground at the tip, but return all the way back to your ground block. 100mH choke in series with the power, as close as possible to the light. 1uF 20V ceramic cap across the power inputs. That will take care of high frequency stuff, you can use additional progressively higher values for caps depending on the frequency of the noise if present.
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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.

Last edited by rocketbob : 01-15-2012 at 05:28 PM.
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  #3  
Old 01-15-2012, 06:03 PM
BillFear BillFear is offline
 
Join Date: Oct 2007
Location: Sherrills Ford, NC (Lake norman area)
Posts: 432
Default LED help

Hi Bob,

No can do on the wiring, it is in and staying! I just tore one of these apart and it appears they have 3 cree xr-e leds in series. Can I just get rid of the driver board and run them directly from the 13.8v supply power. Or can I add a resistor which I understand are completely quiet.

Cree specs show 3.7 volt forwarding voltage and 1000 ma forwarding current at 3.7 volts for the XR-E diodes.
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  #4  
Old 01-15-2012, 06:31 PM
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CharlieWaffles CharlieWaffles is offline
 
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Location: West Linn, Oregon
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Default

Matronics has a fix for this issue specifically - https://matronics.com/aeroelectric/C...ECcatalog.html. It is at the bottom of the page.
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  #5  
Old 01-15-2012, 06:50 PM
krw5927 krw5927 is offline
 
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Got a link to the light you bought, Bill? I'd sure like to check them out for my 9A.
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  #6  
Old 01-16-2012, 08:28 AM
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rocketbob rocketbob is offline
 
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Resistor is not a good idea for high intensity LEDs because as the bus voltage varies so will the current since it will just be proportional to that voltage, which may exceed the LED's maximum current ratings. Therefore you can't run safely at maximum current and you won't have the maximum brightness.
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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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  #7  
Old 01-16-2012, 09:00 PM
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NDrv8r NDrv8r is offline
 
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Default Led vs resistor



Uploaded with ImageShack.us

this is 2 sets of 3 Cree lamps in series. I am using a 2.5 ohm 10 watt resistor in series with each 3 lamp set. You are correct that the amps drop with volts. I have a plane power alternator and odyssey battery. My Dynon reports the voltage as 14.7. at 14.7 volts, the current is .98 amps. The aircraft voltage does not drop much with low power on landing, and I am very pleased with this set up. There is zero rfi. The dropping resistors are absorbing about 2.7 watts of power. WAAAY less heat than the 75 watt mr16 heat lamps er, landing lights.
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  #8  
Old 01-16-2012, 11:55 PM
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CharlieWaffles CharlieWaffles is offline
 
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Those are nice. Have a part number/seller of those handy by chance?
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  #9  
Old 01-17-2012, 07:01 AM
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rocketbob rocketbob is offline
 
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Pic of my wingtip lights. The LEDs are Crees, larger one is the landing light, the smaller one is a taxi light. Works very well.

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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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  #10  
Old 01-17-2012, 09:16 AM
BillFear BillFear is offline
 
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Location: Sherrills Ford, NC (Lake norman area)
Posts: 432
Default Send us your specs

Bob/Larry, please send the specs on the CREE LEDs you used.

Kurt, I would not recommend the MR16 I bought. The controller is very noisy. Experimenting yesterday, I bypassed it and ran the 3 leds in series with 4 ohms to attempt to get 1000ma thru them. They were very bright, for a minute and then the solder melted and the LEDS feel off the little round board they were attached to. (partially my fault as it was no connected to its heat sink). I think the mfgr in China quoted the wrong LEDs in the assembly, they claimed they were Cree XR-E, who knows what they really are.
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