Cree yacht lighting - need constant current driver source

Hi all, I am retrofitting some incandescent lighting in a boat to LED. It's nothing fancy, just two 1W Cree XR-Es on aluminum bar stock being powered by LuxDrive 350mA drivers. I have a bunch of fixtures to build, so at $14 each, driver cost is adding up. Is there anything else I can use that will cost less? I see DX has some stuff that may work, but can I trust it to not burn an expensive boat to the ground?



Specs: 12VDC system, 2x1W Cree LEDs, prefer under 400mA drive power.

Thanks so much!

asimba2 said:

Hi all, I am retrofitting some incandescent lighting in a boat to LED. It's nothing fancy, just two 1W Cree XR-Es on aluminum bar stock being powered by LuxDrive 350mA drivers. I have a bunch of fixtures to build, so at $14 each, driver cost is adding up. Is there anything else I can use that will cost less? I see DX has some stuff that may work, but can I trust it to not burn an expensive boat to the ground?



Specs: 12VDC system, 2x1W Cree LEDs, prefer under 400mA drive power.

Thanks so much!

Click to expand...

well, its not a wired version, more of a PCB pinout, but these work for me nicely for automotive retrofits. Efficiency is a tad lower than the Buckpuck [~87% on my tests], but they are about 1/3 of the price. Smaller too, roughly 0.9" x 0.4" x 0.3"
Input Voltage: 9 VDC to 36 VDC
Output Voltage: 2 VDC to 32 VDC

MeanWell LDD-350L: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2155903_-1
If Jameco happens to be out of stock, Mouser Electronics Ref: 709-LDD-350L

Shipping from Jameco is pretty decent, it only gets expensive when you start ordering pounds of it.

The Mean Wells are really, really nice DC/DC converters. I would certainly prefer them over LuxDrive anything which cost more and are less durable.

However (and I feel bad for doing this), if you just want straight 350mA or 700mA DC conversion from a 12-24v DC source Satistronics sells a variety of DC/DC converters for about $1.25. They are typically used in MR-16 retrofits, but I've used them in everything else by the dozens. They are rugged and cheap. Unless cost savings is a flat out priority I'd go with the Mean Wells.

Wow, those Meanwells look really nice, especially for the price. I have used their AC drivers for household circuits, so I know and trust the name. Thanks for the tips, I had no idea these were available!

Illum said:

well, its not a wired version, more of a PCB pinout, but these work for me nicely for automotive retrofits. Efficiency is a tad lower than the Buckpuck [~87% on my tests], but they are about 1/3 of the price. Smaller too, roughly 0.9" x 0.4" x 0.3"
Input Voltage: 9 VDC to 36 VDC
Output Voltage: 2 VDC to 32 VDC

MeanWell LDD-350L: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2155903_-1
If Jameco happens to be out of stock, Mouser Electronics Ref: 709-LDD-350L

Shipping from Jameco is pretty decent, it only gets expensive when you start ordering pounds of it.

Click to expand...

Think I'll be buying those (or something similar) next time I do any 12V DC work - costs a dollar or so more than buying components to roll my own, but are certainly more efficient and perhaps even more reliable.

They come in several flavors: 300ma, 350ma, 500ma, 600ma, 700ma
Mouser Electronics have all of them, but they want $8.06 before shipping for them
Jameco only has the 300, 350, 500, 600 flavors for MW Drivers of this particular size and dimension

I do roll my own drivers once awhile, but I have no idea how they managed to get it to fit in a little potting box like that.
Its based on the LM393, driver schematics are pretty simple. I use a circuit sightly modified from the Velleman K8071 Circuit

9-18V, 350ma or 700ma [Actually, theres no limit if you vary the sense resistors, maximum 840ma] and theres definite potential, in combination with a thermistor, for IC1A to be configured as a thermal foldback circuit. This could be useful even at 350ma if the fixture is enclosed with little or no moving air.

Just a thought... everyone knows that switching power supplies generate a lot of noise right? Have you considered the effects of the conducted and radiated noise from whatever power supply you use? i.e. will it interfere with the various radio or navigation systems on the boat?

I deal with these sorts of issues in my daily job, and you'd be surprised how much noise some switching power supplies can make! Even when applied correctly, I've seen some greatly exceed the current marine regulations. I'm thinking of one switching power supply evaluation board from National Semiconductor that was just awful. When I talked to their applications engineer, I found out that they really aren't designing for any standards for emissions. They have no idea how noisy their parts are.

Instead of spending $8 or $14 for a switching power supply, how about just adding a third LED, reducing the current a bit, and just using a linear current regulator (or a resistor, if you are so inclined)?? No problems with emissions, just a bit more power dissipation, and probably less cost. You might spend some of those savings on a better heatsink, though.

regards,
Steve K.

:thinking:

The Mean Well LDD series handles 56volts input. While this may seem like overkill, I'm going to bet those buggers can take substantial abuse in a marine or automotive voltage environments. I can can kill a LuxDrive by looking at it the wrong way.

heh, slap a zener across the input [I.E. say something like a 50V zener, BZX55B51] and it should be good against spikes up to 75V.
How come my luck with luxdrive has been mostly positive compared to alot of people, the only time I fried a buckpuck is running 3 XPGs at 1A off 24V. It simply decided to overheat. Bought another, overheated just the same. Interesting, if its going to overheat why is this setup illustrated in the datasheet?

Illum said:

:thinking:

Click to expand...

hey Illum, was that :thinking: in reference to my post? I'd be happy to explain or clarify my post, if desired.

My point was that there are regulations that have to be met for a lot of types of lighting applications. For marine applications (i.e. boats), there are specific limits on radiated RF emissions. There are also practical limits, such as not obviously interfering with communications or navigation equipment. The last thing anyone wants to find out is that a boat that they designed lights for got lost at sea or burned up or some other tragedy.

Obviously, the same thing applies to lighting for our homes. If the place burns down because the electronics that you designed/built started the fire, then the insurance company isn't going to be happy with you.

Steve K.

Steve K said:

hey Illum, was that :thinking: in reference to my post? I'd be happy to explain or clarify my post, if desired.

Click to expand...

I had placed a joke there citing the use of large ferrite beads to shield the MW driver since its so small, then I realized as I had little content to backup in context it would have been largely a fluff post, so I deleted it

okay.. ferrites are handy tools, as are small ceramic caps. A few zeners or transorbs can be handy too.

I only mentioned the EMC regulations and such because most people aren't aware that there are regulations about this stuff, and certainly wouldn't know what it takes to test for it. (answer: it takes some very expensive gear to run these tests! My employer has well over a million dollars invested in this stuff). Making flashlights or bike lights (in my case) is not a problem, since you can't cause much trouble. Ships are a whole different thing, though!

Steve K.

I wasn't sure how the switching driver would effect communications either, so I built one light housing for the boat and put it into service last year; so far there have not been any issues and they love the light. Now I'm building a bunch more, but generally this lighting is only used when the boat is anchored and therefore not running the engines or nav/communication equipment. The boat owner is a family member, I am not running a business or anything, so if they don't work out it's no big deal.

This is a 42' trawler, not a mega-yacht, so once the boat is anchored the largest electrical drain is from the lighting. By switching out the overhead fixtures from 22 watt incandescent to 2.1 watts of LED light, the we can go considerably longer without starting the diesel generator.

Illum said:

They come in several flavors: 300ma, 350ma, 500ma, 600ma, 700ma
Mouser Electronics have all of them, but they want $8.06 before shipping for them
Jameco only has the 300, 350, 500, 600 flavors for MW Drivers of this particular size and dimension

I do roll my own drivers once awhile, but I have no idea how they managed to get it to fit in a little potting box like that.
Its based on the LM393, driver schematics are pretty simple. I use a circuit sightly modified from the Velleman K8071 Circuit

9-18V, 350ma or 700ma [Actually, theres no limit if you vary the sense resistors, maximum 840ma] and theres definite potential, in combination with a thermistor, for IC1A to be configured as a thermal foldback circuit. This could be useful even at 350ma if the fixture is enclosed with little or no moving air.

Click to expand...

sir where is the pin1 of lm393 connected to in this circuit
and can a normal 1 ohm 1/2 watt resistors be used in place of R6 and R7 , i am going to use this circuit to drive 2 3W leds on a 12 volt 2 amp DC power input n pls suggest suitable mods...kindly help

Very helpful diagram, thanks

aniket17 said:

sir where is the pin1 of lm393 connected to in this circuit
and can a normal 1 ohm 1/2 watt resistors be used in place of R6 and R7 , i am going to use this circuit to drive 2 3W leds on a 12 volt 2 amp DC power input n pls suggest suitable mods...kindly help

Click to expand...

This was copied verbatim from the kit's pdf
http://www.esr.co.uk/manuals/k8071.pdf

The LM393 has two voltage comparators on board, the circuit uses only one, so the output pin of one comparator is left floating.

I don't see why not, a single 1 ohm 1/2W from the looks of it will operate the LEDs at 700mA. I'd say build it and test the LED current till you find a resistor most suitable.