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Author Topic: Led power, a stinky business... Or am I wrong?  (Read 3697 times)
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Poty
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« on: May 14, 2023, 06:29:23 18:29 »

Hello!:
After a long time, I put this subject to your consideration:
Since I live in a pretty insecure place (no discussions about that, please), I had set a few security cameras outside my house. Fortunatelly, the free space around my house is big, but this becomes a problem for those cameras, because their maximum reach is 30 meters (100ft aprox.), so, the infrarred light included in the cameras is not enough to reach longer distances (night mode). So, I decided to build a simple IR high power led lamp, using, of course, a 3W IR led with a convector lens, following this reasoning:
If a simple 5mm IR led, which uses 1.8 to 2.1V and 20mA., consumes (P=I.V) between 0.036 and 0.04W, and lets dim this with a 70% of wasted energy, lets suppose that we get a minimum useful power of 0.0252W each one.
WIth the same suposition, I considered that a 3W led (reducedto a  50% of efficiency because the convector led), provides 1.5W of useful power.
So, a 3W led should illuminate as almost 60 5mm leds....
I bought 3 of those, and test one... with a regulated power source to avoid any error, and using a heat sink to keep led safe....
Disappointment is a soft word to describe what I got....
This sh**** led has a little more power than 3 of the 5mm common ones... at least to my eyes, but that was evaluated using a night vision camera, pointing the camera a little away from the led distant focus... I mean, over a surface at 3m from the camera and the led!!!!
In fact, it can´t be seen the point where the led was pointed at... seems that doesn´t reach even 3m (10ft)....
Besides that, 3W led specifications indicate 1.6V and 700mA, wich was carefully sourced... But 1.6V*700mA means 1.12W...
So, I felt a little stupid... and asked to chatGPT... and this thing answered a very abstract response... Like "vendors define led power as the maximum it can reach before burn down, but it dependos on the vendor"....
Then I felt more stupid, so, I came here to bother you, and ask if any of you had dealt with some similar to this?
Thanks in advance.
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Manuel
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« Reply #1 on: May 14, 2023, 06:39:57 18:39 »

Dear Poty,

1st) Check the emission angle !
2nd) Chose narrow emission angle possibly.
3rd) you can not think a LED is able to light an open environment with just 3W.
4th) I suggest you to use common LED with movement sensor ... can help more.
5th) why do not you try with a spot light 12V 50w to check ?

Just to check even try a series of SFH4550GW model from OSRAM, you have to drive it with max 20ms pulses at 100mA....do the same with the other leds you bought.(with higher current...check datasheet for AMR)

Then can check with LZ4-00R608, always from OSRAM.

I know it is not an easy....to find the right solution.

take care,
X!
« Last Edit: May 14, 2023, 06:46:02 18:46 by Manuel » Logged

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pickit2
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« Reply #2 on: May 14, 2023, 07:10:24 19:10 »

specs say 3W/850nm (100° angle – 3 meter coverage)
most cameras use two or more.
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LabVIEWguru
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« Reply #3 on: May 14, 2023, 10:12:48 22:12 »

1) as Manuel said, check the angle of emission.
2) there are companies that sell silicone or polycarbonate "optics" to "tune" your beam width and shape.
3) Did you get the LEDs from a manufacturer, a reputable supplier or from Ebay? I am just about done buying parts from Ebay.
4) I'm not an optical expert, but we use "COB" (chip on board") and use (I think) 6 in a series circuit with an LED driver and a really large heatsink which gives you something like 35 watts output. 
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Poty
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« Reply #4 on: May 15, 2023, 07:05:31 07:05 »

Thanks to you all for your fast answers! I appreciate this.
As I wrote in my topic, the emission angle of the 3w one was different from the 5mm ones (140º). So, I used a convector lens (optic) to change that angle to 30º... the same as the other leds, and because that, I decided to reduce not to 70%, but to 50% the efficiency of the 3W led..
But something is still buzzing in my ear... how can a 1.6V, 700mA led, use or generate a 3W power? Taking cosmic energy? (LOL)... Seems that those leds I bought are a scam...
Unfortunately, in this country, as you can read in news (if you want, check Argentine economy today, in any news site and you'll understand)
So, I have to stick to what I can get, because buy something from Amazon, Digikey or any similar, is almost impossible because differences between our money and U$S.
I'll try to take some images of what I mean... I have 3 cameras... 1 is Foscam brand, and the other two are chin-chu-lin... (I dont remember the brand, but works good enough. The foscam one, has 30 5mm leds, and extends the night vision pretty clearly to almost 30m.... The other two has only 4 leds, and works flawlessly up to 15 meters... This is the reason that I want to add another source of IR light, and followed the first comment reasoning, but those 3W leds seems a scam to me...
Besides all that, I had to replace all leds from the foscam one, a few months ago, because a big voltage variation from the line, and just burnt leds and not the entire device. At that time, found 850nm and 940nm IR leds... searching on the web, I found that 940nm leds have a better response for the nocturne use. Just let me take some pictures, and show you what I get.
Thanks again.
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vern
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« Reply #5 on: May 15, 2023, 09:00:33 09:00 »

Hi Poty,
1.6V @ 700mA is 1.12W, which is obviously the maximum rating for your LED. I found a similar LED (WEPIR3-S2) which has the same rating.
This is the maximum power for DC applications. The 3W is only for pulsed applications!
However, the most importent information to compare leds is of course the radiation power and the beam angle, which in this case is max 600mW (@ 700mA) and 120 degrees.
Do you have a part number of your LED or a datasheet?
What do you mean by convector lens, I don't know this term? Do you mean a converter lens? Is it a glass lens or plastic? If it's plastic, are you sure it is transparent to 940nm?
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Poty
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« Reply #6 on: May 15, 2023, 05:11:55 17:11 »

Hello again.
I must correct something, and I'm sorry, it was my mistake... It is not a convector lens... (in spanish, convector is some kind of concentrator), the physics term relates to air or more precisely energy transference thru hot gases, so it makes somehow a way into my brain and sounded adequate to describe the effect of this lens... Sorry again, my mistake.
This lenses are COLLIMATORS (found the adequate name), narrowing the spread angle of the original led, from 140º to 30º, and are specifically designed to fit on leds from 1 to 5 or 10W... like this ones:
Pic Nº1: led
Pic Nº2: Lens.
Tonight Iĺl send you some pictures of the IR light effect of 3 devices and this stinky led.
Regards.
« Last Edit: May 15, 2023, 05:19:05 17:19 by Poty » Logged

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kripton2035
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« Reply #7 on: May 15, 2023, 06:17:48 18:17 »

anytime you buy something from an "unreputable" seller aka ebay, ali, etc,
ANY power rating they claim you can divide by 2, even 3 to have the correct value ...
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Poty
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« Reply #8 on: May 16, 2023, 02:45:23 14:45 »

Probably you're right, Krypton. But this is one of the big led sellers in Argentina, started around 2008, or so... even so,  they offer this thing... no reference code, no datasheet, no nothing...
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Manuel
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« Reply #9 on: May 17, 2023, 08:54:30 08:54 »

check the family for visible light...push a lot even at 9V...

https://www.cree-led.com/products/leds/xlamp/

sorry for my bad habits.

take care,
X!
« Last Edit: May 17, 2023, 04:12:40 16:12 by Manuel » Logged

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Poty
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« Reply #10 on: May 19, 2023, 04:28:34 04:28 »

Ok. Since a promise is a promise, I add an attachment to this one, with the link to a repository. Yo can see there 5 jpg files. Those pictures relates to the cameras Iḿ using, and the led I bought.
Pictures 1 and 2 were taken pointing to the same place with Pic1: Camera FHD with 6 hi power IR leds, and pic 2: Camera 720px with 30 x 5mm IR leds. Distance about 30m (100ft)
Pictures 1 and 3: Same brand cameras, different places, pic 1 30m, pic3: 8m approx.
Pictures 4 and 5: Led light effect over a door, 5m distance, pic4: bought 3W IR led, pic 5: 6 hi power IR led from camera.
No way to determine the power of the camera leds, but on results, seems 6 3W leds...
Lets talk later. Regards.
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