# 3 Watt High Powered LED Underwater Transom Mount Fishing Light



## lumenEpps (Mar 25, 2014)

Hello All, 

I just joined the site. After visiting 50+ sites, I stopped here after reading the wealth of knowledge from community members. I hope to frequent and have many posts and comments in the future. I have a background as a store manager at Radio Shack for 8 years, and car stereo industry for 15 years. Remote starters, stereo systems, etc. I have a knowledge in building relays, resisters, diodes, etc. I am hoping I can contribute in the future to the community. 

I read a number of the posts and responses before starting my own thread, not to hi-jack a previous post. 

I am needing some input with an LED project I have been working on. I am building an underwater LED transom (Boat) mounted light. I have seen dozens of these all of the internet, from $500 to over $1,000 each. Ridiculous when you consider the materials to build one yourself. I've spent the last 3 months researching the type of enclosure and materials and making my purchases across the globe to be shipped in.



GOAL: Build two 24 LED (72 watt) transom light in GREEN and in BLUE. Optical grade epoxy potting, encapsulating the LED's and all connections for waterproofing. Enclosure is black ABS plastic enclosure (avoiding salt water corrosion) Large block corrosion resistant heatsink + thermal paste for heat dissipation. 30 foot Teflon coated wire to switch, battery terminal. 

This gentleman at loomisLED has created exactly what I hope to accomplish. He states he is an MIT graduate, with 25 years of experience. His light has no special drivers or components, but driven only by the length of the wire (35 ft). 30,000 hours of life on the LED's. He hand builds these lights in his workshop and sells to the public. The light cannot be run out of the water for more than 4 minutes, for cooling purposes. Claims it has been tested in 100 degree salt water.

Link removed. New members links can be suspect, not that this one is.




THE PROBLEM: I completed my enclosure, performed static pressure testing and dynamic pressure testing. LED's mounted on aluminum plate, then mounted to aluminum heatsink, embedded in thermal paste, and finally encapsulated in epoxy optically clear resin. However when I submerged the light, and connected the power source, within 5 minutes the epoxy cracked (like glass) I am assuming I am not getting enough heat dissipation. 

I'm not sure where I am going wrong in my assembly to get these overheating results



The LED Specs are as follows:

3w:

700mA 
*green:*DC Forward Voltage:3.4V~3.8V Forward Current: 600-700mA
blue:DC Forward Voltage:3.6V~3.8V Forward Current: 600-700mA
Green 510~530 nw
Blue 460~475 nw

Any input or recommendations to my build would be much appreciated. I hope to post pictures of the progress. Maybe the project build can earn a "Sticky" later


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## jason 77 (Mar 26, 2014)

Pictures of what you currently have would help a lot. You said heat sinking paste for the LED's, are you securing them down mechanically if not then I think you need thermal epoxy. Also what kind of "Optical grade epoxy potting" are you using, what are it's specs? How are you managing current and voltage going to the LEDs? How are you wiring them up?


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## Steve K (Mar 26, 2014)

have you considered the coefficients of thermal expansion? i.e. the aluminum will expand somewhat when it warms up. The epoxy will also change in dimension, but probably not as much as the aluminum. If the epoxy is bonded to the aluminum, the aluminum might expand more than the epoxy does, and the epoxy could crack.


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## lumenEpps (Mar 27, 2014)

I have been trying to post the pictures I have, I have really good images of everything which would help illustrate where I am going with this. However, it isn't letting me post links to my images. Newbie privileges are limited I suppose. 

So I would be willing to hire someone knowledgeable that can help with the design aspects.

I am assembling everything literally by hand. I was going to use artic silver, thermal adhesive, to seat the LED's onto the aluminum plate, under the plate is my aluminum heatsink.

The optically clear is a new product with MG Chemicals 8322. More resistant to salt water, marine applications. Wired in parallel. Using a 12 vdc 3 amp power supply, True RMS Volt meter to measure current.

@ Steve, I have a think layer of vinyl on the aluminum for an aesthetic look, before the potting epoxy is poured. I'm not sure how much heat I am generating on the surface of the aluminum, as I am not testing under conditions with ambient air. I have to fully encapsulate so it can be submerged. The surrounding water is essential for cooling the enclosure.

Should I run a strip of metal through the enclosure wall to make contact with the water, so the heat can disperse?


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## WeLight (Mar 27, 2014)

which specific leds are you using, the mechanical design of the led relative to epoxying the device might be a mismatch. Leds emit most of their heat south however a proportion comes out the top with light


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## Steve K (Mar 27, 2014)

lumenEpps said:


> @ Steve, I have a think layer of vinyl on the aluminum for an aesthetic look, before the potting epoxy is poured. I'm not sure how much heat I am generating on the surface of the aluminum, as I am not testing under conditions with ambient air. I have to fully encapsulate so it can be submerged. The surrounding water is essential for cooling the enclosure.
> 
> Should I run a strip of metal through the enclosure wall to make contact with the water, so the heat can disperse?



There should be aluminum in contact with the water if the heat is going to be conducted to the water. I imagine that the aluminum will have some sort of treatment or paint to protect it from salt water, though. If the vinyl is between the aluminum and the potting, that will help to some degree, but the aluminum will still expand and the LEDs will still be in firm contact with the aluminum and the potting (I assume). That will still cause mechanical stress on the potting. 

As an electrical engineer, I have run into a lot of problems with potting causing broken electrical components. Fortunately, I can usually work with a mechanical engineer to resolve the issue. Without benefit of a M.E., it seems like your best options are to either keep the aluminum from getting very warm, or else allow motion between the aluminum and the potting.


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## lumenEpps (Mar 27, 2014)

Steve, great input. What do you think about this.

Behind or on the bottom of the enclosure, create a couple of holes (preferably on the bottom) so when the boat is trailered the water will automatically drain from gravity. 

I'm not certain the best way to waterproof an aluminum heatsink, salt water corrosion proof. Powder coating? I wouldn't want to put an epoxy or compound on the heatsink blades and create more thermal resistance. Water will come in direct contact with the heat sink, so I would think there would be very little aluminum movement, as the water is keeping everything thermally low in temperature, just like you said. 

Ideas on protecting a heatsink?


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## Steve K (Mar 28, 2014)

I'm not going to be much help on the issue of protecting aluminum from corrosion. You'll have to research that on your own.

Regarding keeping the clear potting from cracking, I'd suggest installing some temperature sensors on the aluminum plate, and gradually increasing the power delivered to the LEDs. This will give you an idea how warm you can let the aluminum get before the potting cracks, and that can help you when developing the heatsink and corrosion protection designs. 

Changing subjects slightly... how are you handling the issue of water entry at the cable? I've seen issues with water wicking up the wire strands on some designs.


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## lumenEpps (Mar 28, 2014)

I actually redesigned the enclosure and dropped the heatsink altogether. I am going to have the surrounding water enter the case to make direct contact with the aluminum plate the LED's are mounted on. The water entering similar to a cofferdam should cool thermally far more efficiently. Water has a higher thermal conductivity than air, it can move heat faster than air, water has a higher heat capacity than air.

On the cable entry, I used a marine grade epoxy made from locktite. The cable is made from military spec Teflon. 

At this stage I need to find suitable driver. The buckpuck won't work according to David at LED driver. c o m. with 8 strings of 3, It will need a driver with output current of 5,600 ma to deliver 700 ma to each LED. The most powerful driver they have is a buckblock which only has an output current of 2100 ma. 

I'll look on lux drive and see if I can find something. I may have to build something from scratch. I'm not overly concerned about the steady current delivered to the LED's with the engine running, or off. However I do want protection from transient spikes, surges in the system from running other pumps or devices.


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## DIWdiver (Mar 28, 2014)

I don't think you want to keep still water in a coffer around your heatsink. I say open the whole thing up, and get as direct a path as possible from the back of the LEDs through the aluminum to the open sea.

The thermal conductivity of water is way better than air, but it's way less than aluminum. Once you've warmed the water a bit, you want it to go away and be replaced by cooler water ASAP.

There are a number of drivers available in your range. Taskled makes great ones. CPF member Der Wichtel makes a 5A one, that would be pretty close. Those are both switchers and would have high efficiency. www.Led-tech.de offers some inexpensive 2.8A drivers with integrated heatsinks. They look like linears, which would be about 78% efficiency in this application. Two of them would work. I make an adjustable linear that would also work, and is designed for automotive applications, which this is pretty close to. 

At the low end of the price range, something like this should work too. It's also a switcher so should have good efficiency. http://www.ebay.com/itm/DC-8A-80W-A...597?pt=LH_DefaultDomain_0&hash=item5402fda2dd

Keep in mind that you can't run strings of blue in parallel with strings of green on a single driver. You can run blue and green in series in a single string, and you can run equivalent strings in parallel i.e. 2B1G with 2B1G. But strings that don't have the same number of blues and the same number of greens shouldn't be run in parallel, i.e. 2B1G with 1B2G.

If you're going to split them up and run 2 drivers at 2.8A each, you open up a whole lot of other drivers. Dealextreme, Kaidomain, and others offer both linear and switching drivers that are very cheap. They're also very inexpensive. Lumileds and others offer better ones, at higher prices.

If you're thinking about adjusting the brightness of each color to get a mix that you like (or if I just got you thinking about that), then having at least one adjustable driver would be a good idea. Adjustable drivers are available at all but the very low end of the price range.


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## lumenEpps (Mar 28, 2014)

Hi DIWdiver, you're exactly right. I appreciate your response! I scrapped the heat sink all together and will open two holes on the bottom of the enclosure and two more on the top, to create a reservoir that continually recirculates water through the enclosure to make contact with the aluminum. 

Tell me more about you driver. Do you have any pictures, specs? I will be running four lights on my boat, 2 green and 2 blue, and exactly as you said. Mounting them side by side, so I can make turquois, running them simultaneously or individually green or blue. I definitely wouldn't mix the strings in each enclosure, different specifications on each LED bead color and all. 

I do like the 8a one you linked on ebay, that would be suitable. I can mount it inside an enclosure as well. Ideally it would be nice to have one driver to operate two lights. Using two drivers versus 4. Sort of like a double pole double throw switch. On this one you noted, I could at a potentiometer to dim, like you said. Great minds think alike, I think that would be a very nice feature to dial it down. Have you seen any drivers with a pot built in, or a connection to add a pot and mount it to a panel?


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## DIWdiver (Mar 29, 2014)

Some of the Taskled drivers have an onboard pot, some can use an external pot. Mine has both. Meanwell also makes some with external pot capability. Anything with an onboard pot should be adjusted only occasionally, as many of the tiny pots that are used have a very limited mechanical lifespan (I've seen as low as 20 times, but 100 is more common).

With my driver, I know it's a VERY bad idea to connect an LED to a driver that's powered up. That's how I blew my SST-90. I suspect the same might be true of some (not all) other drivers as well. So I would not advise using a switch to connect different strings to a single driver, unless you can somehow ensure that the switch can't be changed while the driver is powered. That is, unless you have specific info about the driver that says that's safe.

Any linear driver in that power range will need serious heatsinking (like the LEDs). Switchers will need quite a bit less, or possibly none at all. Ones in cases like the eBay one I linked, or the Meanwells, will most likely need none.

If you were adventurous, you could remove the pot from that eBay driver and wire in your own external pot.

Here's a link to my sales thread: http://www.candlepowerforums.com/vb...Automotive-linear-13-5A-LED-driver-adjustable


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## lumenEpps (Mar 29, 2014)

DIWdiver, let me ask you. Would a single one of your drivers be able to run two of my lights? Maybe adding in a diode on the second light to isolate it. Just to be clear, with you driver I can set the current threshold, and VDC threshold on the driver itself, and then use the external pot to dial it up and down, thus the dimming effect? I would like to add two switches on the dash of he boat, and two dimmer pots below each switch. Each switch will operate 2 lights. The finished product will have one GREEN switch X's 2 GREEN LEDS (72 watts x's 2 lights 144 watts total) and a second switch to operate the two blue LED lights. I would mark up a schematic rendering if the site would let me post image links.

Or

Should I just get 4 of those inexpensive LED's from ebay and isolate all four lights. I can solder in an external pot off the board of the existing built-in pot. Or put an in-line dimmer control on the load, between the driver and the lights.

BTW: I may get a couple or more of your drivers anyway, for another upcoming LED project I am working on. I looked at the data sheets on your driver, very impressive. It may be a little overkill for this particular project, because it does so much, and has a higher operating range than I need for the marine LED's. How soon could you have one ready? If you think the cheapy from ebay is a good driver, I'll go ahead and order a couple. So I can keep moving forward with the testing. Thanks!A


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## lumenEpps (Mar 29, 2014)

What do you think about this one:

Since I still can't post direct links, go to ebay and copy and paste the description below on the ebay search. 

5-30V to 0.8-28V DC Boost-Buck Converter 5A Constant Current Volt Regulator


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## DIWdiver (Mar 29, 2014)

That looks like it might work pretty well. It's available with a dual meter board stacked on top, still under $10. Without seeing what they actually ship, I'd be suspicious of the build quality, but the pictures they show look pretty good.

The one with the meter on top says you need to add heatsinking for outputs >3A.

Yes, one IS1011 would drive two lights, each one being 8 strings of 3 LEDs (aka 3S8P), each string being driven at 700 mA. That's a total of 16*0.7 = 11.2A. You can set it up to 13.5A. The driver would need serious heatsinking, as it would be dissipating somewhere around 50W.

There's no voltage threshold, the driver takes care of that itself. You set the current output you want using a combination of the onboard and external pots, or the onboard pot and external switch for high/low/off. You could set the onboard pot for 11.2A, then use external pot for dimming from there.

I currently have 3 in stock. After those sell out, it will probably be around a month before I have more. I'm really busy for the next week, after that I want to make a few changes on the board before ordering more, then it takes 2-3 weeks to get boards and a few days to build and test a few.

If the controls will be more than a few feet from the driver, I recommend using shielded cable for the wiring. I have that in stock if you need it.


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## lumenEpps (Mar 29, 2014)

Ok great! Just so I know on these particular drivers. Are you putting the pot in-line on the output to the light? Or are you soldering them to the underside of the existing pot mounted on the board? Do you have a favorite, recommended pot in this application?


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## Tortus (Mar 29, 2014)

I just registered because I'm looking to do almost the same thing.

Great thread, and it looks like my timing is perfect.


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## lumenEpps (Mar 29, 2014)

Jump on in Tortus, the water's fine

DIWdiver, check out this driver. It's a monster, good price too. Sizable pair of heat sinks too.


http://www.ebay.com/itm/DC-to-DC-10-32V-to-10-46V-150W-Boost-constant-current-power-supply-LED-DRIVER/301114014970?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D21142%26meid%3D5839154383052340591%26pid%3D100005%26prg%3D9373%26rk%3D2%26rkt%3D6%26sd%3D141218167805&rt=nc


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## DIWdiver (Mar 29, 2014)

lumenEpps said:


> Ok great! Just so I know on these particular drivers. Are you putting the pot in-line on the output to the light? Or are you soldering them to the underside of the existing pot mounted on the board? Do you have a favorite, recommended pot in this application?



On the IS1011, the pot goes in the control circuit, so it sees very low current.

For the eBay linked part, you should remove the existing pot and replace with your own. This is also in the control side, so sees very low current.

As a result of the low current, a wide range of pots are suitable. For these two drivers, anything from 1K to 10K is good.


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## DIWdiver (Mar 29, 2014)

lumenEpps said:


> Jump on in Tortus, the water's fine
> 
> DIWdiver, check out this driver. It's a monster, good price too. Sizable pair of heat sinks too.
> 
> ...



Yes, that appears to be a nice part.


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## lumenEpps (Mar 30, 2014)

Because the 8 amp driver will be overrated for the light, which only needs 5.3 amps, I suppose the best thing to do would be add a rated wirewound metal oxide resister for current limiting so as not to over supply the light. 

I've ordered all the parts, so I will post an update later this week. 

Keep me in mind for 2 of your drivers in the next month when you have time to build more. Count me in!


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## DIWdiver (Mar 30, 2014)

If it's an adjustable driver, you won't need the resistor. That's the point of the driver.


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## lumenEpps (Mar 30, 2014)

I meant for the sake of not overpowering the light by limiting the possible current supplied to the light. I can always set that at the driver or a limit on the pot. Just thinking to avoid doing it by accident.


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## Tortus (Mar 31, 2014)

I'm going to try using the 5w drivers for mine. Once I get the shipment I'll test the output to let you know how much power they really do put out. I don't think it will be a problem to be .3 amps shy across a total of 24 leds.


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## lumenEpps (Mar 31, 2014)

Tortus, probably will be fine running the 5 amp. I was running 4 LEDs underpowered on a 3 amp supply and they were doing just fine. I'm just always been a proponent of not running devices/circuitry at their peak. I always seem to overcompensate :-0

DIWdiver, curious if you have had any personal experience with RGB LEDs? a controller/driver for them to rotate through the color spectrum. I've used them on LED strip lighting and tubes. Pleased with the results. I was considering duplicating this same project, with RGB LED beads. 

http://www.ebay.com/itm/50pcs-3W-Hi...443?pt=LH_DefaultDomain_0&hash=item51bb830b2b

Just looking at the variables on specs. The only major variance is in the RED LED with a drop in VDC handling, Curious what your thoughts are with these. All in one driver, that sort of thing.


Parameter​Value​​​Lens​Water Clear​Emitted Color​Red, Green, Blue​Viewing Angle​120°​Forward Current​300mA​Forward Voltage​Red​2V to 2.5V​Green​3.2V to 3.6V​Blue​3.2V to 3.8V​Wave Length​Red​620 to 623nm​Green​520 to 523nm​Blue​460 to 465nm​Intensity Typical​Red​30 to .5 Lm​Green​40 to 45 Lm​Blue​15 to 20Lm​


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## DIWdiver (Mar 31, 2014)

I wrote the firmware to make certain colors using a panel of RGB leds. Unfortunately, it's commercial property (not mine) so I can't share it, but there's really not much to it but to turn different colors on at different intensities (using either analog or PWM dimming).

I've also done mixing on several different red/green LEDs to get red, green and amber for battery status indication. You have to have the right wavelengths or you can't get a decent amber that is easily distinguishable from the red.

The wavelengths on the RGB one must have been well chosen, because mixing was really easy. The only color that's tricky to get right is white.

Unfortunately, I don't remember the wavelengths on the RG ones, and never knew the RGB ones. 

Yes, different colors have different voltages. Been that way forever, probably always will be. Longer wavelengths have lower voltages. Infrared ones are around 1.1-1.5V.


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## Tortus (Mar 31, 2014)

By the way, I'm thinking about using copper for my heat sink instead of aluminum. Copper doesn't expand as much, and removes heat faster. It will be a little more expensive, but may be worth it. 

I'm curios what everyone's thoughts are on that?


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## DIWdiver (Mar 31, 2014)

More expensive and harder to work with, as well as heavier, but definitely better thermal properties. Often not necessary, but (almost) never a problem.


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## lumenEpps (Apr 1, 2014)

That's alright, cant share a job for someone else, intellectual property and all.


I can agree with that, white is the precise mixture to get it right. I'm going to put this one aside for a future project coming up soon.

Tortus, Copper not being iron based won't corrode...but it will tarnish slowly. Not sure if yours will be visible to aesthetically matter. I still like Aluminum.


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## lumenEpps (Apr 21, 2014)

DIWdiver, regarding the 100 watt LED chips. Do you know if these 100 watt LED chips can be encapsulated? In the environment they will be in, I see condensation as an issue. I want to thin coat encapsulate them, then mount on an aluminum surface, with direct contact with water behind it. Clear lens over it. Maybe offset it, with spacers so water can get behind the boat fiberglass and the aluminum, to cool it.


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## DIWdiver (Apr 21, 2014)

Not really my field of expertise, but I know enough to be dangerous. I would mount first, then encapsulate. Any encapsulation must be optically very clear, and fairly heat resistant. Lots of things turn yellow quickly at elevated temps, and absorbing optical energy increases temperature. Any encapsulation that's both a bit thick and very rigid (like epoxy) can cause extreme and possibly damaging stress in the underlying components. In other words, you have to be very careful in your selection of encapsulant.

Flowing water as close as possible to the emitter will keep temperatures down.


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## FRITZHID (Apr 22, 2014)

DIWdiver said:


> Not really my field of expertise, but I know enough to be dangerous. I would mount first, then encapsulate. Any encapsulation must be optically very clear, and fairly heat resistant. Lots of things turn yellow quickly at elevated temps, and absorbing optical energy increases temperature. Any encapsulation that's both a bit thick and very rigid (like epoxy) can cause extreme and possibly damaging stress in the underlying components. In other words, you have to be very careful in your selection of encapsulant.
> 
> Flowing water as close as possible to the emitter will keep temperatures down.



Absolutely correct, many accelerant cured products are going to conflict with both high heat, uv AND water/pressure resistance. 
If this were my project, I'd look into an optically clear tube type design using a clear oil (mineral oil for example) as both a pressure resist and coolant.
Mounting would then be very simple. Heat and pressure would not be an issue. Just my 2¢ worth.


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## lumenEpps (Apr 27, 2014)

Thank you DIWdiver and FRITZHID, I appreciate the input. I have an MG Chemicals 8322c optically clear potting epoxy, specifically engineered for LED potting. Saltwater corrosion proof, etc. The tech at MG said it could handle high temp without yellowing or fading. Temps up to 230 degrees Celsius. It does good so far in dynamic pressure testing and static. So far so good. 

MY concern was condensation or moisture, so a need to protect the LED chip from corrosion was important. Mounting on aluminum surface with direct contact to water, flowing behind the plate to cool it.

My challenge is getting a THIN coat of epoxy, on a flat surface without it running everywhere, when I bake it for 2 hours to cure. Need to do some kind of mold, r dam to keep the epoxy from running everywhere. I haven't come up with a solution so far.


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## DIWdiver (Apr 27, 2014)

Excellent. Sounds like you were very careful in your selection of encapsulant!

We pour some stuff on a board at work, that cures into a gel, and it's supposed to be around 1/4" thick. They just rim the board with electrical tape for a dam. It's ugly, but it works. I would have added a wooden form around it to keep the tape upright. As it is the pressure from the uncured material makes the tape lean out, so it looks strange when you remove it!


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## lumenEpps (Apr 27, 2014)

That's a remarkable idea DIWdiver. So for the form make a wood mold, round in my case...like a ring. Line the outside with electrical tape so it can release from the mold when the epoxy cures. Baking is only 175F so the wood should be fine. I don't mind it not looking "pretty" as I am mounting a lens over it and the aesthetics wont matter. As long as it protects the LED chip! 

It sounds like yours at work works out well. It doesn't seep under the board when liquefied?


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## DIWdiver (Apr 28, 2014)

They make a mess of everything in the area when they do it. So it's kind of hard to tell if it seeps under, but having looked at a number of the boards after it's done, I'd say rarely if ever.

That temp might make a mess of the adhesive on electrical tape. If you have access to Kapton, it's much better. Not as sticky, but on a round board, who cares?


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## lumenEpps (Apr 29, 2014)

That's a good tip, I ordered some Kapton tape to use. It seems like it will do the job. Who says getting the job done doesn't come without making a mess!

Do you make any boost bucks. Stepping up the voltage/current from a 12 or 24 volt DC system, to 30v-34v range? I know you have the other driver you said you made.


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## DIWdiver (Apr 29, 2014)

None for public consumption. I've made some for clients. It's a lot more work, so I tend to want to get paid.

Also, I made those two drivers to fill a niche market that I didn't think would get filled otherwise. There's plenty of switchers coming out, so I have little desire to try to compete.


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