Diy LED lighting

Discussion in 'D.I.Y.' started by Shaheedo, Mar 7, 2012.

  1. Greystoke
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    Greystoke Specialist

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    Very ingeneous Shaheed. Good work.

    Water cooling may well become a solution for hi-light tanks. We need this sort of experience.
     
  2. Shaheedo
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    Shaheedo Algae harvester

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    Hi Cor
    By using water cooling you will be able to cram a lot more high power LEDs without the big expensive heatsinks. And the heat generated does not go to waist just my driver gets to about 40deg.

    Have you got any Data so I can compare my LED light to a 1.2m t5 light with reflector. I am planning to upgrade my light to have the light output of 2 T5s but I need a reference point to work from


    Regards
    Shaheed
     
  3. Greystoke
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    I'll look it up.
    Are the 2 T5's under one reflector or does each one have its own?
    What's the Wattage of the T5?
     
  4. Greystoke
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    I've taken the "Sylvania AQUASTAR T5" as a model. It's 1150mm long @54Watt, 2800Lumen. PAR/Watt =0.92
    Total output is therefore: 0.92 x 54 ≈ 50 PAR per light tube.

    If they're both under one reflector you lose about 15%. If each has its own reflector this could be just 5%.
    Take worst case: 2 x 50 x 85% = 85 PAR.

    Let me know if you need more info:
     
  5. Shaheedo
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    Shaheedo Algae harvester

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    Thanks Cor

    Is this a HO tube? and how much +/- does it cost

    If I used cree LEDs I would of have the light output of this tube. If I can increase LED drive current then i might come close the that light output but then I must jipo the driver and thats a bit risky if there is no ajustabe pot inside
     
  6. Greystoke
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    That particular tube is pretty expensive. I would go for any 6500 T5 daylight that's within your budget. Failing that: buy a 6500K T8 daylight. They are reorted to go for under R30 each, and there's nothing wrong with T8.

    Oh yes, I forgot that you need to add a bit of PAR to compensate for the heat loss on the LED junction. That's about 10% @ 70 °C, which means that you are looking for ≈ 90PAR.
    (By all means, jippo the driver if you know what you're doing. I always did, and I learned a lot of lessons that way, good as well as bad ::))

    Which reminds me:
    Your watercooling system: Do you think it should incorporate a thermal cut-off to switch-off the driver in case the return water somehow stopped? That would prevent frying your LEDs.
     
  7. Shaheedo
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    Shaheedo Algae harvester

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    Hi Cor
    I found a shop on ebay selling 1w 90-100lm LED beads 10 for 3$ with shipping and 30w 320mA LED driver for 12$ with shipping at DX.com

    30leds @ 90lm is 2700lm :) almost maching the Sylvania AQUASTAR T5

    http://dx.com/p/waterproof-320ma-30w-power-constant-current-source-led-driver-85-265v-42905

    http://www.ebay.com/itm/10-Pcs-1W-High-Power-6500K-Cool-White-Led-Lamp-Beads-90-100-Lm-Kitchen-/120934891795?pt=LH_DefaultDomain_0&hash=item1c28480113

    I want to mount these LED directly on my aluminium bar with no star plate. What comination of will give be the best PAR.
    20 x 3000k and 10 x 6000k

    or

    10 x 6000k and 20 x 3000k

    or have you got any other sugestions

    Regards
    shaheed
     
  8. Greystoke
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    Thanks for that info.
    I wonder if you can parallel these drivers?

    The general recommended ratio is: 1 to 2, 3000 to 6000.

    BTW: Don't forget that last question of mine re: watercooling etc


    PS: I think I found the manufacturer of this LED. Comes from Taiwan and they are available in White, Warm White, Green, Blue. From the info I understand that these are Cree clones.
    http://www.alibaba.com/product-free/100347861/1w_3w_High_Power_LED_Emitter.html
     
  9. dougbb
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    I'm really liking this thread, reminds me of a project I never finished! I've just woken up so May have missed it, but I think the leds should be able to be cooled without the water, e.g. fan. So you use the water cooling until your tank reaches certain set temp them to avoid over heating it switches fans on. With an arduino the coding is very short and components are cheap too.
     
  10. Greystoke
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    Which really means that we need an alternative cooling system.

    My new proposed tank will have a surface are of 1.8 x 0.3 = 0.54m ². A medium PAR level would be ≈ 55PAR (102PAR/m ²), and the corresponding heat generated by the LEDs would be about 44 Watt.
    This energy must be removed, although it might be OK in winter, but in summer we'll overheat the tank and its contents.

    Air cooling the LEDs maybe preferable to cooling the tank. That would take a lot of water to evaporate.

    So we need a LED cooling system that can be air or water cooled.
     
  11. dougbb
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    Agreed, Don't think it will be that difficult. Finned heat sinks or even just a fan pulling air away from the LED's could work. I've got 3 watt LEDS on a piece of aluminium, it gets warm but not hot, thats with no cooling system, obviously they have to be well spaced though...
     
  12. Greystoke
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    But if that's the case we might as well stick to forced air cooling. Additional water cooling will just become a complication.
     
  13. dougbb
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    I'm always a sucker for an extra complication, could justify it by saying would save costs on heating the tank ;)
     
  14. Greystoke
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    Well, you got that right ;D
     
  15. amazinmic
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    Great Thread, leaves me inspired.

    Although I am a bit of a lazy bugger...
     
  16. Shaheedo
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    Shaheedo Algae harvester

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    The complication make it interesting ;D .... And I cant resist.

    @Cor
    The 12 LEDs I got on the aluminium bar can run without water cooling it gets to about 30deg. The LED is also not running @100% (de-rated to670mA).

    Any way you got me thinking (was distracted with my LED find on my last post ::)) I want to put a non return valve on the water input on the LED tube. I saw it in a Midas ad about R15 it is used in a opel corsa. If my filter stops working water wont drain from the bar, I positioned the output so there is always 1cm of water in the bar. So my 15mm thick aluminium rectangular tube will be like a solid aluminium bar

    When I done my B-tech thesis I built a voltage source switch mode power supply with temperature feedback to drive LEDs it worked well for 1 LED and I could get the max out the LED. I used a thermistor (temperature dependent resistor) in the feedback of the switch mode to follow the de-rating of the LED.
    You could run a LED on a very small heatsink at its max in any ambient temperature. There are problems/complications using a voltage source but that made it interesting ;D.

    In the future I want to build a current source with temperature feedback (or figure out how to jipo my LED current driver just need to figure out how the current sensing feedback works) it will be not to complicated to build but I want to use a switch mode power supply for the efficiency.
    I should be able to get 30% more light from the LEDs and if the water cooling failed the LEDs will be automatically de-rated to a safe working temp at that heatsink temp.

    Cor, if you mount your LEDS on a 20x20mm aluminium tube it will take up very little space, looking at you LED light position you need it to be small. Then you an use 5mm air tube to divert some water into the tube or use a power head. Water is more efficient than air.

    You can also try to use water and air, when air flows over water the water gets colder. If you can get water to trickle through the tube and a fan blowing in from the top . if it does not work out you can glue some small heat sinks on the tube the ones they use on the power transistors (that was my back up plan).

    Regards
    Shaheed
    D
     
  17. Greystoke
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    He he,
    Confusius says: All will come to those who wait.


    @ Shaheed
    Where - on earth - do you get all these brilliant (and very practical) ideas from? [​IMG]
    I'm really impressed with your thermistor derating idea. Simple and effective.

    This "over heating" issue is likely to cause problems when you go for medium and hi lighting, particularly in summer.

    On the other hand I might be exagerating this. Fluorescents also create a lot of heat, but its never a real problem because there's enough surrounding cooling space.
    I just need to get this old brain revving up a bit and think about it some more.

    BTW: I updated the LED files again. I included LUXEON (Philips) LEDs, and . . . I improved the heat sink estimator by adding Lumen output and RED/BLUE ratio. So now you can mix cool-whites and warm-whites untill you get an R/B ratio of about 0.9

    (The R/B ratio is an important factor affecting plant growth. The closer you can get it to ≈0.9 - sunlight=0.92 - the better.)
     
  18. Shaheedo
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    Shaheedo Algae harvester

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    I dont like the yellowish tint in the 3000k LED's , and i like the effect of the red LED,s it makes the fish look more colourful.

    So i am considering adding 20 6000k LED's and 10 red LED's. I assume the 3000k LED's are the to get some red spectrum

    What i found on the net was that you need the blue and red to grow plants and and over 6000k has a lot of blue
     
  19. Greystoke
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    Just for that purpose I added a Cree Blue LED, which you could use to increase the bue spectrum of the 3000K LEDs.

    On a total of 85.2 PAR I needed 61 PAR from the 3000K LEDs and 21.4 PAR from the Blue LEDs (or 4300Lm and 627Lm) to get an R/B ratio of 0.92

    I'll include a RED LED to the list, so you can do this exercise by combining them with 6500K LEDs.

    Watch this space. ;D
     
  20. Greystoke
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    Surprise, surprise.

    The 6500K LEDs already sport a 0.70 R/B ratio. This means that you don't need a lot of red LEDs to get this to 0.92. In fact I only needed 1 in 15 red LEDs to get there, i.e.: 30 x 6500K LEDs and just 2 x red LEDs
    That's not a good proposition because you don't get an even distribution.
     

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