Porch Lighting

[Led1]

I am pondering a thought to build a LED porch light for the front and rear entries to my house. The current fixtures have 13w Warm White CFLs in them, and they do not have motion sensors.

I want to build some new fixtures utilizing LED because they have that "instant on" startup anytime of the year, whereas the CFLs really start to be bothersome in the winter months. Also I want to start using them as security lighting with the addition of a motion sensor.

I am considering the MC-Es for the LEDs of choice in the Neutral White color. I'm not sure on the lumen output is for a 13w CFL is but, I would think that 2 MC-Es would be comparable?

Which driver would any of you recommend to run 2 MC-Es? I didn't know which AC to DC converter would be best, and not be overkill on the project. My guess would have been a 12w Xitanium driver.

Is my math correct on the total wattage for using 2 MC-Es? 12.8(vf) x .35(mA) x 2(MC-Es) = 8.96w + driver inefficiencies

Thanks guys… any information would be helpful

 

[Led1]

Delete

 

[Led1]

When deciding on heatsinks, is it better to get the fins closer together or spaced further apart?

 

[moonfish]

I think you could power it with one of these http://www.powergatellc.com/pdfs/LPC-20.pdf I'm looking at something similar and I'm looking at those drivers because of reasonable price.

For passive cooling, you want fins spaced farther apart. How big of a heatsink do you plan to use? I don't know the square inch per die or per watt ratio.

 

[James Jackson]

I would recommend making them an amber color - not white.
But - that's just what I did. The reason being that the white seems to attract bugs.
My front porch light works very well - using 4 amber Luxeon star LEDs - granted... they're yesterday's technology - I think I'm getting about 25 to 30 lumens per LED - and I have 4 of them.
The total light output seems to be adequate... for the front porch.
I use an InfraRed remote to turn on/off the light - which is cool, as we can turn the light on prior to exiting our vehicle - 20 feet away.

Regards,

James Jackson
Oztronics

 

[Led1]

I think you could power it with one of these http://www.powergatellc.com/pdfs/LPC-20.pdf I'm looking at something similar and I'm looking at those drivers because of reasonable price.

For passive cooling, you want fins spaced farther apart. How big of a heatsink do you plan to use? I don't know the square inch per die or per watt ratio.

I'll look into that driver I'm not sure if I am going to add a fan to my setup yet, that possibility is still an option. I'm thinking 3" x 3" with 1" fins (1 for each LED)

I would recommend making them an amber color - not white.
But - that's just what I did. The reason being that the white seems to attract bugs.
My front porch light works very well - using 4 amber Luxeon star LEDs - granted... they're yesterday's technology - I think I'm getting about 25 to 30 lumens per LED - and I have 4 of them.
The total light output seems to be adequate... for the front porch.
I use an InfraRed remote to turn on/off the light - which is cool, as we can turn the light on prior to exiting our vehicle - 20 feet away.

Regards,

James Jackson
Oztronics

I like the IR remote idea, sounds cool. As for the amber I might do that for the rear door fixture since we will be there more during the summer months. The front will be more for us coming, going and security so I would like it bright as possible.

To give everyone an idea on what the fixture currently looks like

 

[blasterman]

Do you intend to mount the LEDs in the fixture you posted?

so I would like it bright as possible.

Bad thing to say around here.

 

[Illum]

I am considering the MC-Es for the LEDs of choice in the Neutral White color. I'm not sure on the lumen output is for a 13w CFL is but, I would think that 2 MC-Es would be comparable?

Disregard the lumen measurements when considering the switch over, because the lumen output of a CFL exits 360 degrees around a sphere, LED lumens exit only 100 degrees off a plane. So it would be very hard to match the lumens of a CFL unless your mounting 3-4 LEDs facing different directions.

"white" comes in a couple different variations, MCEs are offered in Cool white, Neutral White, and warm white. cool white is not natural white...at all. Neutral white is, warm white will put you into near amber range depending on the exact bin you wish to use.

Which driver would any of you recommend to run 2 MC-Es? I didn't know which AC to DC converter would be best, and not be overkill on the project. My guess would have been a 12w Xitanium driver.

the Xitanium 12W driver will only pump 350ma into the LED string, which many would consider to be too dim. Also, the 12W driver is up to 32.6V max, the 700ma driver only goes up to 24.6V, meaning if you want a higher current setup, you might have to opt for 2 drivers, one for each LED.

When deciding on heatsinks, is it better to get the fins closer together or spaced further apart?

Fin pitch is determined by the cooling method. The denser the fins are, the less free flowing air can pass through it, but if your going to use a forced air cooling system, that is...with a fan installed, then have the fins as close as possible. But otherwise for passive convection cooling I'd recommend wider gaps. Also make note the heatsink volume and material. Some materials do not conduct heat well, titanium and steel are among the examples.

 

[Led1]

Do you intend to mount the LEDs in the fixture you posted?



Bad thing to say around here.

LOL. That was referring to the color spectrum, white to amber. Yes that is the fixture for the retrofit.:tinfoil:

 

[Led1]

The cooling plan right now is going to be passive. The fixture has space so I might add a computer fan in there later. I plan on using an aluminum heat sink.

The N.White MC-E produce 370 lumen at 350mA. I would think that's pretty bright. By bumping it up to 700mA, how much of an output increase should I expect?

I'm thinking of going with three LEDs to make the light more well rounded. Two angled and one facing downward. ugh! The more I disect this project the more it seems to unravel lol...

Given the housing that I have to use, what would you all suggest I use?

 

[LukeA]

You'll get much better lifetime from LEDs at 350mA, and from experience 370 lumens is pretty decent, especially when you consider that the LED won't waste half or more of its light shining into its own shade the way an incandescent would.

For a driver, I just used a 12V 500mA switching power supply (the best kind of wall wart, and I think I paid like $6 apiece for them from Digikey or Mouser) and a resistor calculated to allow 350mA through to the three LEDs in series. The driver cost was under $7 per fixture.

 

[Led1]

You'll get much better lifetime from LEDs at 350mA, and from experience 370 lumens is pretty decent, especially when you consider that the LED won't waste half or more of its light shining into its own shade the way an incandescent would.

For a driver, I just used a 12V 500mA switching power supply (the best kind of wall wart, and I think I paid like $6 apiece for them from Digikey or Mouser) and a resistor calculated to allow 350mA through to the three LEDs in series. The driver cost was under $7 per fixture.

Thank you for your input LukeA :twothumbs

 

[blasterman]

The more I disect this project the more it seems to unravel lol...

It happens Pretty straightforward project though. 700-1000 lumens of neutral white will make a very adequate porchlight.

First issue is your heatsink isn't big enough, but I work with ones that are.

Is there enough room in that housing for a 5.5" square by 1.5" tall heatsink? We'll start with that.

 

[lonesouth]

unless you diffuse the light, it may be rather blinding as you approach the door, but that may be by design...

 

[Illum]

"Don't plan too far ahead" may seem counterintuitive at first but trust me, the more you plan the more you become overwhelmied by the accompanying information.

I've been trying to build an LED table light...I started in May and the first prototype hasn't gotten built yet

 

[blasterman]

I've been trying to build an LED table light

You must be one of those 30million Americans/Canadians smart enough to wire a DC circuit and is smarter than the aisle manager at Walmart {where our technology needs should be determined}.

Sorry...couldn't resist.

I build em' ...I just come up with a better idea half way through and never complete the first one

We need to solve the heatsink issue first on this one. The rest is a piece of cake.

 

[Led1]

"Don't plan too far ahead" may seem counterintuitive at first but trust me, the more you plan the more you become overwhelmied by the accompanying information.

I've been trying to build an LED table light...I started in May and the first prototype hasn't gotten built yet

Thanks... I actually dropped everything for the last couple of days and started reading a book lol (Shutter Island). I had time to rethink my purpose for the light. Instant on/off capability with the use of the motion sensor and better lighting. Oh yeah my need to tinker with things

I thought those LED tables were the coolest thing when I first saw them. I don't think I would have the patience to do that job with my 2 year old always pulling me this way or that way.

Was this what you were referring to?
http://www.youtube.com/watch?v=IkmpIXd9Q90&feature=player_embedded

To make thinks more simplistic would going to a Bridgelux (BXRA-N1200-00000). I figured where the light is being installed that I really do not need three MC-Es running in different directions. One large LED pointing down will do the job. I am looking to use copper for the heat sink, no luck in locating one at this point in time lol, still looking though (might have to fabricate one...)

 

[Illum]

not really, a regular desk light...just too much stuff to tweak.

its a red and white light in one, the collapsed profile the size of a cinderblock but when expanded enough to light a 2x4 table. Red or white selection with dimming capability.


To a point you just have to shoot the engineer and build the light

 

[Josey]

A porch light should shine directly down, not out or into your eyes as you walk to the door. It should light up the stairs and the door handle/lock. You don't need very much light. 700 lumens is way too much, unless you going to sit out there and read. 40 lumens would be enough.

You can google the dark-sky movement to get some ideas.

 

[moonfish]

Look at the screen porch thread. I think you don't need so much output. Too much, especially a nasty hotspot could crapcan what night vision you have and you'll end up tripping on the steps after you go to all this work.