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Old 27-12-2010, 08:18   #16
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And even the common instruments, radio, vhf, ssb, ham radios, all will start to show failures at 15 volts. They're all spec'd for 13.8V (which is nominal "low" alternator voltage) with a +-10% tolerance, for a mximum of 15.18 volts before things fail.
That's the industry standard for tolerances--
While I agree with your argument to design for a max of 15 volts, there is no "industry standard" for power supply tolerance. In fact, you'll find that +/- 15% is the most common including Icom but current models of Standard VHF's is 13.8 +/- 20%. Some equipment is rated at 13.6v +/-, some 13.8v +/-. B&G instruments are 10-16 volts and a lot of equipment other than 2-way radio's can operate 10-40 volts.

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Old 27-12-2010, 09:34   #17
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Wouldn't it be easier to spend the $150?
spoken like someone with an income!

$150 is a lot of money to me, 2 hours is not.

Besides, I've learned a good deal about LED's and how to make electrical engineers argue
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Old 27-12-2010, 18:01   #18
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Besides, I've learned a good deal about LED's and how to make electrical engineers argue
Heh! This thread sure got some engineers fired up. You should have enough expert LED info now to make a 3 year project out of your simple question.
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Old 29-12-2010, 00:40   #19
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One point I believe has been overlooked. Navigation lights have very precise beam patterns which are given in the ColRegs.

Can you ensure that the DIY light will meet the standards? Perhaps part of the cost of the manufactured bulbs is ensuring they are legal.
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Old 29-12-2010, 08:02   #20
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Can you ensure that the DIY light will meet the standards? Perhaps part of the cost of the manufactured bulbs is ensuring they are legal.
From what I've heard, it's a fairly significant part of the cost. Getting a nav light tested and approved by the various authorities is a tedious and time-consuming process; some manufacturers don't even bother.

Building lights on your own might work, but it does pose an additional risk (other than the technical issues). If you are involved in a collision, and the other party claims he didn't see your nav lights, one of the lawyers will eventually discover that you were using non-standard, non-approved lights. That would be a bad situation to be in.

OTOH, certified/approved LED tricolours often command obscene prices, hundreds of dollars or more. So maybe there's a case for making your own LED lamp (or using something like a Bebi that's popular and reliable, but not "approved") with which to be seen, and also fitting the cheapest "approved" lights you can find, to turn on as needed?
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Old 29-12-2010, 08:04   #21
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the LED's are inside one of these nifty trilight/anchor light housings, the lenses on the housing should help compensate for any overlap.
expensive masthead tri-light on ebay

PS I should mention that only 10% of my navigation is after dark, far from shipping channels and usually 10-20 miles off shore, the current bulb draws too much amperage and is not visible enough for my comfort
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Old 29-12-2010, 10:40   #22
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Bruce, "bulbs" don't and can't meet the USCG COLREGS requirements, which are for "lamps" or "lights" or "lamp fixtures" however you might want to call them. The USCG doesn't approve "bulbs" per se, just complete assemblies, and that is partly because you need the complete assembly in order to cut off the beam as sharply as the regs require. No bulb, LED or tungsten, has a sharp cut-off pattern all by itself.

Tungsten bulbs are usually a 360 degree output (varying somewhat, depending on the design and how the base, etc. obstructs tham) while LEDs tend to provide a "cone" with a 10 to 180 degree spread. The brighter ones have a smaller cone, if you want a wide bright cone you may pay $8-10 each. The specs for the brightness and spread are always available from the manufacturer.

Submitting a complete "assembly" to the USCG for approval probably is expensive but to touch on another argument--CG approval isn't required by COLREGs. The regs require *performance* and the approval is only one indication that a light does perform properly--when it is fresh out of the box with a proper voltage supply and other criteria. The folks who are worried about liability suits for using their own lights, tend to forget they can still be sued even with a USCG approved nav light.
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Old 29-12-2010, 11:52   #23
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Very true, hellosailor, and frankly I wouldn't be too worried about the USCG certification issue as it pertains to liability in a collision. But if you go build your own lights, and they end up not complying with COLREGS, and you end up in a collision/legal situation.... well, it could be a big point against you.
In other words: Research the regulations and the technology enough to know what you're doing. Don't just slap something together and assume that because it turns on and makes light, it'll be OK.
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Old 29-12-2010, 11:58   #24
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Matt, I agree with you. It is easy enough to far exceed the minimums COLREGs calls for, and easy enough to spec LEDs for the job. The only hard part is paying for them.<G> With the "good stuff" running ten bucks a pop, or close enough to that, and factoring in coverage and redundancy and protective devices and allowing for aging out and all...No matter how you slice it, a good job will be expensive. Nothing new about that.<G>

Of course I know that if I did build the bulletproof superbright masthead light combo, it would get struck by lightning within 90 days and need replacing anyway. The old joke about how many Microsoft programmers does it take to change a light bulb: "None, the new standard is darkness."
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Old 29-12-2010, 12:07   #25
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Here's a quick circuit that will run as many 5VDC LEDs as you like (Up to 5 AMPs worth)
You can just keep adding LEDs in Parrell at the end, remember each LED gets a 200 Ohm resistor. The L1003 regulator can hold up to 5 AMPs and costs less than $5 ($1 in qty of 100)
Replace the L1003 with a 7805 and it will run at 1 AMP output, less LEDs of course. Lower price.
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Old 29-12-2010, 12:43   #26
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Actually the size of the resistor (above) depends on the LED, but 200 ohms should be good for most LEDs

The formula is R=V/I or R=5vdc/.03amps =166 ohms but 200ohms is the next standard size.
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Old 29-12-2010, 13:04   #27
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Funny how some people actually enjoy cobbling together their own hardware. Of course there is also a very great danger of learning something in the process. It really is much safer in that event to just spend the money.
I hope this is sarcasm......god forbid someone might enjoy tinkering and learning
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Old 29-12-2010, 13:18   #28
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I confess to having done some frightening tinkering...like using a rock to replace a defective thermostat. (Hey, it worked pretty well.<G>)

But with LEDs...really, there's not much point in tinkering when there's internet access to SO much good technical information. Information on thermal management (because you can burn them out if you ignore this and use high power LEDs) and calculators that make resistor selection SO easy. It was a "ROFL moment" last time I was in Rat Shack looking for an LED, to pull out a smartphone with a free calculator app on it, and match up the resistor I needed on the spot.

Don, I don't know if the L1003 is old or new, but Google makes it look like a snark--can't find one. The 78xx regulators are a good choice though, they're sold everyplace except WalMart and CVS now.<G>

While the 200 ohm resistor will certainly protect LEDs...but with a 5V source voltage, it may also only provide 1/4 of the power they need, so someone winds up using 4 LEDs for every one they really need, and could properly use. (Properly, i.e. reasonable rated brightness and life.) Not so hard to run the numbers and use matching parts.

LED selection is just like sail trim, or poker. Anybody can do it, but if you pay attention to the details, you can REALLY do it better.

And here's a hint: If firecrackers are illegal where anyone lives, just stick an LED into a wall socket. WHAM! Hard to have so much fun for so little cost. Shrapnel and burns aside.

I don't think you'll find any online tech resources about how to do that properly.
<VBG>
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Old 29-12-2010, 14:15   #29
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Sorry, Typo LT1003

As far as tinkering, It's fun. I like making things. Just like I like working on my bike/car/boat.


Do the same thing with an electrolytic capacitor and watch it fly through the roof. (How do I know that will happen?)


Better stop giving the kiddies ideas.
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Old 29-12-2010, 14:26   #30
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LEDs are current devices, not voltage devices. You really need a current regulator to drive them properly, not a voltage regulator with resistors in series with the LED. You use LEDs for 2 reasons. Longevity and efficiency. By adding dropping resistors you are negating the efficiency to a large degree.
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