Some VERY interesting LED modules

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No, Jouke … that’s the wrong way round

0.5 Kelvin temperature rise per Watt needs a bigger heatsink than 1.77 Kelvin temperature rise per Watt

MichaelG.

Sorry for my stupid thinking. I should do better!

It is normal physics, so to say.

Edited By Jouke van der Veen on 14/01/2023 20:29:30

No problem, Jouke … it’s an easy mistake to make

MichaelG.

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I’ve found the data-sheet : **LINK**

https://dammedia.osram.info/im/bin/osram-dam-12454646/Datasheet_QCS_QI_11_1CH_EN.pdf

MichaelG.

Hello Everyone,

In the past we have used the Luxdrive constant current drivers to run these modules. All though they are 'only' 350mA they work very well and the modules are still very bright. These little Boostpuck drivers are small, around an inch square with and has adjustable current pot on the bottom.

They can be run from a 5V to 28V input with a max V out of 48V. This are ideal for running these modules at 5, 12, 24 Volt etc

Luxdrive model number is: 4015-D-I-350, from what I remember they are fairly low cost.

I have attached some pics of the drivers and also, just out of interest, I have attached some pics of some hard anodised enclosures that were made specifically for a one off project. These had glass fronts and also had two o-rings to seal the module making it totally waterproof. Unfortunately, these are not available but may have the drawings somewhere.

Thanks

Paul

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Welcome, Paul … and thanks for a great first post !!

MichaelG.

For me, I think I have power supplies sorted but I'm still unsure about heatsink requirements. One of the things that attracted me to these arrays was the possibility of making low-profile lights - from the data sheet:

"One example of an innovative application of the OrionTM is Plessey’s ability to re-create an
LED version of the AR111, for a track spot, at less than 25mm in depth including LEDs, optics
and a heatsink. Further information can be found in the OrionTM application notes."

It sounds like other contributors to this thread already have heatsinks which are up to the job (possibly bulkier than Plessey suggest), but I haven't, so will have to buy or make them myself. Probably the latter.

I haven't yet found Plessey's application notes, which I had hoped might shed light.

Robert, that sounds like you have a formula for the heat dissipation from a flat plate of aluminium given (I'm guessing) a point source. I've been making some simple calculations of radiative dissipation because that's all I have in my toolbox. For your putative 23cm square sheet at 140C and ambient 25C I get a dissipation of around 120W, but that's assuming that the whole sheet is at 140 degrees, and ignores convective heat loss. So unrealistic assumptions, but not a crazy result. If you have a formula it would save a lot of head scratching.

It may well be that I'm worrying unduly - Paul's interesting photos (welcome to the forum from me too Paul) don't show a heatsink other than the housing.

Robin.

Edited By Robin Graham on 17/01/2023 00:47:08

Edited By Robin Graham on 17/01/2023 01:00:21

Edited By Robin Graham on 17/01/2023 01:02:40

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I would posit that Pail neatly side-stepped the problem of heat dissipation by under-running the LEDs.

MichaelG.

Another member of the family : **LINK**

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjxttTDis78AhUVRsAKHUpKDE0QFnoECAkQAQ&url=http%3A%2F%2Fstatic6.arrow.com%2Faropdfconversion%2Fb9ae5dcc185c2186e4f432f726450770ca23f96f%2F407866088439439plws1000c0-series-orion-mini-beam-forming-.pdf&usg=AOvVaw1RqxV_l1QEQLjmEcqNK59E

Sorry about the weird hyperlink

Some useful plots included.

MichaelG.

EUREKA !

THE APPLICATION NOTE :

**LINK**

https://www.mouser.jp/pdfdocs/PLWS3000-Series-Orion-Beam-Forming-Module-Application-Note.pdf

MichaelG.

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Edit: __ It’s well-presented, and very informative.

Edited By Michael Gilligan on 17/01/2023 07:56:16

Thanks Michael for the last link. It seems to contradict the datasheet regarding polarity and the use of heat sink compound.

Les.

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It does indeed

I suspect that the datasheet was written for a wider audience, and is therefore more ‘risk-averse’

MichaelG.

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Units arrived today … and the mystery of the electrical terminations is solved

Hiding under the plastic cover is this:

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Note: the ideal implement for opening the cover is on my Swiss Army Knife

MichaelG.

The two of these that I ordered also arrived today. I first tested one with a 64 ohm resistive load and the voltage across this was 44 volts. (Which is a current of 687.5 mA
Here is a picture of the inside just using the flatbed scanner. (The main cover is removed in the same way as the terminal cover by pressing down on the place where the clips are with a small screwdriver.)

I notice that the price of these drivers has now gone up to £7.00.

Les.

Weren’t we fortunate to grab them whilst they were on discount

Thanks again for spotting them, Les

MichaelG.

Excellent! It is indeed informative. Interestingly, the third-party heatsinks they mention don't meet their claim of a <25mm total depth - for example the MechaTronix unit they show has a height of 68mm. Maybe the ones they designed in-house are much more efficient.

On thermal paste, the application note doesn't actually contradict the datasheet. Looking at the (small print!) footnotes to table 2 the use of pastes, gels and adhesives is not recommended.

I've been looking around for cheap heatsinks which might do the job and came across this offering on eBay:

Diameter - 76mm
Base height - 8mm
Pin height - 59mm
Pin diameter - 2mm
154 pins.

The seller doesn't give the thermal resistance and hasn't yet responded to my enquiry, but it may be that there is someone out there who can just look at it and say it'll be fine (or not).

I too grabbed some 240V drivers before the price went up, so thanks from me as well Les.

Robin.

Edited By Robin Graham on 17/01/2023 23:39:09

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Quite so, Robin

The point being [as per my comment to Les] that the application note is written for ‘responsible adults’ and the datasheet is written for a wider audience.

i.e. we are seeing the distinction between not recommended and do not

MichaelG.

Hi Robin,

The for the WH25 resistor I made no calculations. All the information came off the datasheet. The reference heatsink (230mm x 230mm x 1mm aluminium sheet) is a very poor design. In comparison to the heatsink the resistor is a point source. A engieered heatsink to keep the resistor (any 25W source) just touch safe (60 deg C) at 25 deg ambient would be 1.4 C/W.
There are few practical devices, other than heaters that put power into contact areas bigger than a few square centimeters. The area on the LED modules is quite large.

Robert G8RPI.

Indeed. power dissipation dropped by at least 50%. His housing will actually dissipate a lot of heat. The shape of a thin area and tube in middle means there will be a temeperature gradient actoss the LED "puck" with a cool ring where the tube contacts and getting hotter towards the middle and edge. This might affect reliability but under running by 50% will help.

Robert G8RPI..

The notes on the table of heat teansfer materials say greases, gells and adhesives are not recommended for use with the orion modules.
Always read the notes!