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 > "10 watt" LED

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landyacht318

Near a large body of salty water

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Posted: 02/12/18 10:18pm Link  |  Quote  |  Print  |  Notify Moderator

A while ago, as an experiment, I bought a 12v outdoor landscape light that claimed 10w warm white.

TO NO one's surprise it did not consume 10 watts, and while it did respond to a PWM LED dimmer, the range of adjustment was pretty poor so I did not use the dimmer thereafter.

It failed today. I'd estimate no more than 600 hours maximum total use.

When I feed it 13vDC, the LEd just flickers not close to coming on at full brightness. When i remove 12vDC is flickers once a bit brighter then flickers for a few seconds longer.

Now this was inexpensive, but to me it seems like a fairly good waterproof design, which can have a better LED attached to the fairly substantial housing/heatsink. with little effort. It did not get hot, merely warm, when it worked properly when new.



[image]



The circuit board driver does not have that burnt electronic smell, but could be blown for all I know.

They make a "20 watt" version of this light which employs the same housing, so I would be game to upgrade the LED emitter and electronics even if it costs more than buying a better product.

I could also add even more heatsinking.

Call it a learning/ keep it out of the landfill type of project.

I'd love to this housing contain a very powerful LED 12v light that responds nicely to a PWM dimmer, even though I do not really need one.

GordonThree

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Posted: 02/12/18 11:54pm Link  |  Quote  |  Print  |  Notify Moderator

I do agree the best part of a cheap Chinese LED flood light is the housing.

To rebuild it in a fashion that supports external dimming a resistor dropper is your only choice. Any kind of active circuitry, linear or switching would be confused with an external PWM supply.

The driver pictured might be a linear constant current driver, and the big capacitor is the reason for poor response to your external dimmer.

The downside to a resistor dropper is extreme energy waste, especially for a high power LED.

A switching driver with built in dimming and external control support is what I recommend. Like a Luxdrive Buck-puck. It comes with an analog dimming input you can connect a pot to and use as a brightness knob.


2013 KZ Sportsmen Classic 200, 20 ft TT
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MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 02/13/18 12:36pm Link  |  Quote  |  Print  |  Notify Moderator

[image]

CHIP

Power Supply


BETTER

">rAkcjQIpzv6_W3UHOODO7A

  • Make sure (4) 3.5 chip screws are not stripped or bottomed out
  • Insure flat chip mounting surface. I like scuffing with 80 grit
  • Use SILVER heat sink compound -- it really does lower chip operating temp.


">pgAAOSwARZXpf6G]https://www.ebay.com/i........e="mad" alt="[emoticon]">pgAAOSwARZXpf6G

After repairing several dozens of these lights, I seem to have ironed out the bugs. None of my upgrades have failed in 6+ years...

But none of the above addresses the issue of dimming. Use a 5-watt chip and matching power supply?

GordonThree

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Posted: 02/13/18 01:27pm Link  |  Quote  |  Print  |  Notify Moderator

Too many times I've seen those "packaged" drivers being nothing but junk inside. Call me a snob, but I don't buy anything power LED related off eBay, too much scamming going on. Digikey, Mouser and Future Electronics satisfy all my needs, and really aren't that expensive for genuine parts.

Ok, I do buy their LED flood lights, throw the guts away and re-use the housing. Domestic cast/machined housings are stupid expensive.

wa8yxm

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Posted: 02/13/18 04:19pm Link  |  Quote  |  Print  |  Notify Moderator

I have purchased many lED's some from E-bay, (Assorted results none 100% happy but Ill settle for 90) Some Amazon (So far So good, in fact I'm sitting under a 5 meter strip of Amazon Led's for less than 10 bucks as I type. I cut the roll into strips, tape 'em to the backing plate on my Thin Light Florcesent .. after removing all the Florcesent sockets and ballast, and they are N*I*C*E*!!!!!

Long lasting too

and some from other sources where I can check first, (Expensive).

My recommendation is make a small purchase and if it's a good supplier. TAKE NOTES and buy more.. If you want the Amazon page for the COOL WHITE lights I use (I like Cool not Warm) ask and I'll see if I can snag it from my order history.

I don't sell 'em. I just buy 'em.


Home is where I park it.
Kenwood TS-2000 housed in a 2005 Damon Intruder 377


MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 02/13/18 04:34pm Link  |  Quote  |  Print  |  Notify Moderator

Seventeen moolahs for a ten watt driver is beyond what my wallet is willing to part with. And yes, a person has to be careful when buying light emitting diodes or accessories off of eBray.

None of the drivers I purchased have failed from the vendor listed above. Near 100% chip failure of integrated housings/chip assemblies.

The SHARP 30 and 50 watt chips I purchased blow the doors off of the chips I purchased from Mickey Mouser. Better sunlight color, cooler running, and more uniform segment illumination.

For 120vac to 36 volt conversion I use ventilated power supplies. That way I can tweak to match ma to specifics. For instance over my new work bench I backed off voltage to 34.4 from 35.8 (4%) on a 50 watt Sharp chip.

So, as far as I am concerned "blanket statements" about LED components are risky. A Truism however seems to be any 120 vac LED lamp assembly from China should be treated like the electrical components are sub-marginal.

Gdetrailer

PA

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Posted: 02/14/18 05:02pm Link  |  Quote  |  Print  |  Notify Moderator

The LED in that light is known as a "COB" or Chip On Board LED.

Consists of 9 1W LEDs.

You will see that there is three rows of three LEDs, the LEDs in each row are in series and the three rows are in parallel.

[image]

So, no, it doesn't "consume" 10W, it only will consume 3-4W but give the light of about 10 watts worth of LEDs in lumens.

The little power supply is a constant current switching supply which gives the light a broad input voltage of 10V-30V DC.

It was never designed to be dimmable and to make it dimmable you would need to replace that power supply with either a resistor or a constant current supply which has a adjustable output.

I have played with a few of these COBs and they actually are pretty darn good, I have two similar 10W to yours mounted on my tractor for flood lights on the backhoe. Have had those about 3-4yrs now and they do get used a lot.

Also have bought a few of the bare COBs in 10W, 20W and 50W versions.

Had a super 8mm film projector that used a super rare and expensive 36V 80W bulb that blew out while I was in process of transferring my parents super 8 home movies.

Bought one bulb at $80 and the filament was not centered properly and only would light the bottom 1/3 of the film..

Returned that bulb and got another one, it still had a issue with the filament not centered, so it didn't fully light the film but was better than the first one..

So, I took a stab at building a bulb from a COB LED.. tried 10W, not bright enough, 20W, 30W better but not bright enough, 50W almost perfect match for brightness, slightly darker than the original bulb but doable.

The 10W and 20W can be run from 12V, the 30W and up require min of 30V to light them so to use those with 12V you need a 12V - 36V booster regulator..

The only downside I have found with the early COB design is the color temp selection was outside the projector bulb color temp. I was able to buy specially made color gel films to correct that..

For my projector project, I also bought a collator lens to focus and intensify the light output.. Made a huge difference in the film brightness.

As with any of these high power LEDs, heatsink IS a must, never attempt to run without the chip firmly planted to a chunk of metal.

As far as a resistor wasting power goes, yeah, it will but in reality it is extremely low..

For instance that 10W COB only needs about 10V to start glowing, and around a max of 11V for full rated brightness, current was specd at .370A.

A 12V RV system can get to about 14.4V while charging so we need to drop about 3.4V.

I used a 10 Ohm resistor to accomplish the drop.

That resistor I selected only will dissipate 1.2W of heat..

The switching regulator that is used in those lights typically will consume about .5W of wasted heat..

So, yeah, big deal, using a resistor will "waste" an additional whopping .7W!!!

I suspect that the regulator has bought the farm, to check this you can simply disconnect the regulator board, sub in a 10 Ohm 2W resistor..

If the COB lights fully then the culprit was the regulator..

The advantage of using a resistor is it is cheap and you now can DIM the LED. Just be aware that the dimming range is pretty small since the COB will need at least 10V to start making light..

You can upgrade the COB to a higher wattage, just be aware that to do so will require a boost regulator and you still won't have dimming.

GordonThree

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Posted: 02/14/18 05:25pm Link  |  Quote  |  Print  |  Notify Moderator

Lol

Gdetrailer

PA

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Posted: 02/14/18 05:52pm Link  |  Quote  |  Print  |  Notify Moderator

GordonThree wrote:

Lol


I am not sure what you are "laughing" about..

After all, it was YOU that made the statement "The downside to a resistor dropper is extreme energy waste, especially for a high power LED."


.7W extra compared to the 4W the COB consumes is not an "extreme energy waste"..

And YES, those switching regulators WASTE .5W as heat as they are not 100% efficient, 90%-92% at best.

I am laughing at YOUR statement, its pretty darn funny when folks think they know electronics..

[image] [image] [image] [image] [image]

Thanks for the comic relief, I needed that after dealing with stupid wet behind the ears engineers that make twice the money that I make, fixing their stupidity..

GordonThree

Northern Michigan

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Posted: 02/14/18 06:53pm Link  |  Quote  |  Print  |  Notify Moderator

3s 3p led array

Vf(typ) 3.3vdc per chip, x 3 in series = 9.9 volts. Let's round to 10

Ohms law P=V x I ... So 10=10 x I, so I = 1amp

So let's say 13v supply voltage means a resistor needs to drop 3 volts.

Ohms law V=I x R ... So 3=1 x R, thus R=3.3 ohms (nearest easy value)

Ohms law P=I²R ... So P=1 x 3.3, thus P=3.3 watts

I'm a bit rusty... What did I miss?

Of course you can under drive the module to reduce loss but also output.

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