LED lights, take two:

The other day I received an email from Ken James about LED lights and regulators.

This is nothing strange, every time I write an article on how to do something, someone will pipe up, "you know, there is a better way".

Which is as it is should to be, I suppose. Peer review and all, certainly makes for a better end product. For instance, talking to various people has convinced me that the best way to power LED's is though current limiting, and not a fixed voltage regulator. Not to say that the fixed regulator won't work, but there is an easier way. Or, maybe it isn't even an easier way, in some circumstances, but it removes the complicated and expensive voltage regulator and replaces it with a cheap IC at the light locations.

Anyway, I had built the prototype (mark 3) LED anchor light the other day using current regulator IC's from National Semiconductor, some resistors to set the current limit, and some bright white 5.6 candela LED's from BG Micro.

Then I get this letter from Ken James. "Several years ago, over ten now, I had the idea of using leds for nav lights. Retired from the USN, went sailing a bit, then started building led lights. Been at it ever since. Solved all the problems you have encountered, including many you haven't discovered yet, from what I read on your web site ;-) . So now I sell the lights, at www.deepcreekdesign.com."

Funny the people you meet online.

It was actually the high price of the LED lights at Deep Creek that decided me to make my own!

And you know what, after exchanging 16 or so emails with Ken there, I've come to the conclusion I probably didn't save a whole lot of money making my own lights. But, like homemade boat building, that is not really the point.

For instance, Ken pointed out that with the 20 degree spread of my BG Micro LED's a boat would have to be hundreds of feet away to see the anchor light. Seems you need a 60 degree vertical spread to be "legal". Not that I was too concerned with being legal, but I was kind of concerned with getting run into...

So, to make an anchor light with 20 degree 5.6 candela LED's I would need:

360/20= 18 LED's to make a circle of light. But, since they need 60 degrees of vertical spread TOO, I would need three rows of the 20 degree LED's, so I would need 18*3 or FIFTY FOUR of those LED's (which are showing up everywhere and Ebay for about $2.50 each for some reason). Since I really only need 4.2 candela for 2 mile visibility (Ken's numbers) I would need (4.2/5.6)*54= 40 of the expensive little buggers. There is $100 in LED's right there. Plus circuit boards, regulators, etc, I'm just about at what Ken charges for his light!

<sigh>, story of my life.

But wait, he doesn't use 40 LED's on his lights, now what is going on here?

Well, firstly Ken uses a "pulse regulated driver". This means he uses a high efficiency switching regulator, and drives the LED's with pulses of electricity. This gets more "visibility" with the same power output.

Also, Ken uses surface mount LED's with an output of .66 candela. You are thinking that this is quite a bit smaller than the 5.6 candelas of the LED's I was playing with. Well, you must understand that candelas is a measure of brightness, and not total light OUTPUT. His small surface mount LED's only put out .66 candelas, but they put them out in a fan of light 140x60 degrees.

Let's see, that is .66 candelas at 140x60, or 5544 candela degrees (is that even a measurement?)

And, 5.6 candelas at 20x20 is 2240 candela degrees.

So, he is using LED's that are about 2.5 times as efficient as well.

Could I make one using his LED’s? Yes. Nichia sells to the public, but not cheaply. Bought a couple of dozen NSSW440 surface mount white 60x140 LED’s, and used 18 of them for my anchor light. Here is a picture.

Incidentally, if you want to use the surface mount LED’s, you will need a board. I’m considering selling a kit for these lights. If you are interested, email me.

Well, if I can’t save money making my own anchor light, at least I can save money by making my own LED bicolor light then!

Maybe, maybe not. Ken pointed out that if I’m not careful I would have "zone overlap". That is where the beam from the colored LED's overlap and from directly in front of the boat people would see a white light... not good. He was even kind enough to mention ways to get around this problem.

I could certainly build a cheap bicolor light. Would it be as good as the professionally hand made ones at Deep Creek? Probably not. Would it be safe to go sailing with? Probably.

Am I going to build my own lights? You are damn straight. Life, like sailing, is not about the destination, but is about the trip. Making my own LED anchor lights has turned out to be very good learning experience. In the process I have made new friends, learned quite a bit about electronics, and added the skill of etching circuit boards to my boat building skills.

If all you are wanting is efficient lights for your boat, you should buy them from Ken. His are well engineered and come with a warranty.

If you want the learning experience of making your own lights, or just want to tinker, you should make your own. Ask me questions, I'll be happy to help you out.

-Chebacco Richard