LED landing lights

[NDrv8r]

I have been looking at LED landing lights. I began to install the Vans 75 Watt MR16 lamps and realized they will about melt the wing tips off. I also realize there are a number of good alternatives out there, but I just can't leave well enough alone. the picture shown is 3 CREE MCE series lamp modules with reflectors wired in parallel. they are spec'd at 350ma each, putting out 430 lumens for a total of 1290. There are actually 4 LEDs in each module and when driven at 350 ma, there is about 12.1 volts across the module. The common way to drive these is to use a constant current source such as powerpuck. This assures that under varying voltage inputs, there will be a constant light output.

I did some testing with a powerpuck and a spectrum analyzer. It puts out a tremendous amount of radio noise right in the aircraft communications and navigation frequencies. I experimented with filtering and was able to knock it down, but not eliminate it. The nice thing is with a powerpuck is that it is very efficient. With any sort of led, you need to limit the current, so the goal is 1.05 amps to drive the three Cree led packages.

The solution is a common power resistor. The picture shows a 5 watt resistor to limit the current to around 1 amp. My RV7a has a Plane power alternator and an odyssey battery and the system runs at 14.6 volts.



Is the circuit efficient? Well, no, we are wasting about 2.6 watts across the resistor, and the resistor will need to be heat sinked, but the entire circuit is drawing 1 amp vs 7 amps for the 75 Watt MR16 lamp. I have not found a lumen rating for the 75 watt lamp, but the 3 LEDs shown are like looking into the sun!

Next is to figure out a mounting method that will either bolt on without aiming or some reasonable aiming scheme. Stay tuned.

[CharlieWaffles]

What about using one of the LED drivers by AeroElectric to reduce the noise issue?

https://matronics.com/aeroelectric/C...ECcatalog.html (bottom of the page).

[NDrv8r]

The Matronics unit looks great. it costs $46 for the 1000ma unit. I have not had the oportunity to evaluate its RFI characteristics.

A TMC10-2.5 5 watt power resistor costs $4.03 and the RFI is not measurable.

[Veetail88]

Larry, I like it!

Having done some parts browsing on the web I've made up a drawing of what I'm thinking about doing.

If I have the juice, does it matter that controlling them isn't efficient? How durable do you think the power resistor is?

This could be done for under $200 total for a pair of them and they would fit inside the wingtip lenses on my 8.

Total lumens = 1290 per side or 2580. Would that be enough light?

I'm also thinking about mounting with some rod end bearings so the whole unit swivels horizontally and maybe controlling that with a model airplane servo to adjust it for landing or taxi configuration.

Thoughts?



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[rjcthree]

Ok, since I'm a lowly bsme, and ignorant about many things related to electrons, why can't I target to sink off the >12-ish volts through a ballast resistor & zener? No, not efficient, but cheap and no noise. No circuit protection either, but really, if they only last 1000 hours as a result of my abuse, I'm over it. Or maybe just not worry so much about the voltage variation and light intensity variation, and go with as simple resistor drop? At that point, a FET driven current limiting could be implemented . . .

Amy I way underthinking this? Rick 90432

[petehowell]

Originally Posted by rjcthree

Ok, since I'm a lowly bsme, and ignorant about many things related to electrons, why can't I target to sink off the >12-ish volts through a ballast resistor & zener? No, not efficient, but cheap and no noise. No circuit protection either, but really, if they only last 1000 hours as a result of my abuse, I'm over it. Or maybe just not worry so much about the voltage variation and light intensity variation, and go with as simple resistor drop? At that point, a FET driven current limiting could be implemented . . .

Amy I way underthinking this? Rick 90432

Rick, I'm knuckle-dragging BS Aero E, but found while not super efficient, resistors are cheap and quiet. Make sure they are big enough to dissipate the heat. 850 hours later - super bright and super quiet.

[Glastar 5901]

Originally Posted by NDrv8r

The Matronics unit looks great. it costs $46 for the 1000ma unit. I have not had the oportunity to evaluate its RFI characteristics.

A TMC10-2.5 5 watt power resistor costs $4.03 and the RFI is not measurable.

I know this is an old thread, sorry. Is this resistor a 2.5 ohm or a 2.5k ohm? I am going to cobble up one of these assemblies and give it a try! Thanks- Jim

[NDrv8r]

2.5 ohms 5 watts

[Sig600]

I just put two 500 lumen LED MR16 30 degree beam bulbs in to replace my Vans MR16 lights, as they were drawing too much current.

The light out put looks great in the hangar, in the flare and taxi they are worthless. And I do mean worthless, couldn't even tell they were on.

Great for recog though, tower said they could see them just fine. Solved the current draw problem an zero RF noise.

[NDrv8r]

this is what I ended up with. It's a total of 5160 lumens for both wing tips . the lighting is adequate, but it could use a bit more.