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you should not. You need to get constant current source power supply which will supply constant 350mA. You most likely will need to split your LED instead of all 24 in series.
Hi all, I am planning to DIY LED lighting for my 4 ft planted tank.
I plan to plan 24pcs of 1W LEDs (350mA drawing from each LED) in series.
May I know what is the required power supply I need?
If I am getting a standard power adaptor, what rating should I be getting?
Thanks.
you should not. You need to get constant current source power supply which will supply constant 350mA. You most likely will need to split your LED instead of all 24 in series.
Total power required would be the total amount of LEDs you going to use. For your case, the total power required is 24watt at minimum. Personally I would upsize by another 30% to play safe. As for how you going to wire up is another big headache for you.
Please check you LED voltage requirement also.
Hi all, thanks for the guidances. The LED voltage rating is stated 3.3V.
I am thinking of getting a 24V with a current rating of 2A adaptor. If this is sufficient or too much?
Second option, I will split to 2 X 12 LEDs with each having an adaptor of power rating 12V, 1.5A.
Please advise which is better...... Thanks.
Getting abit higher rating Amp will improve the lifespan of the adaptor... =) . Just get a 5Amp if you are worry... The cost is not difference by a lot.....Originally Posted by ynner
you cannot simply select a power supply based on voltage and current ratings only. normal/standard power adaptor will not work.
the most important criteria is constant current output of 350mA or lesser. this must be met else the LED will be damaged if the current flowing through LED is > 350mA.
to determine the minimum voltage required, just multiply 'LED forward voltage (maximum)' by 'number of LED in series'.
thomas liew
As Robert and Thomas has mentioned, it is important that LEDs do receive a constant current, else they will be at a great risk of burning.
If you are unsure, you can get LED drivers from Sim Lim Tower, or from eBay that serves to drive the rated number of LEDs and wattage as what you are intending to use.
With those drivers, you can have a peace of mind knowing that the LEDs will last long if nothing goes terribly wrong.
This one for example helps if you want to split into 2 sets of 12, so that you can control switching different rows or wire them alternately to reduce intensity when needed.
http://www.ebay.com.sg/itm/LED-Drive...ac2bb5b&_uhb=1
This is the one for 24 1W LEDs
http://www.ebay.com.sg/itm/Constant-...599667e&_uhb=1
Current rated at 300mA +/- 5%. Usual power adaptors that you find on the market are just AC to DC, and might not provide constant current to drive the LEDs.
if you are interested on the detail, Google for LED VI curve or Diode VI curve. You notice the curve is exponential, mean the current vary greatly with small amount of voltage fluctuation. Without constant current supply, you can easily over current and burn the LED.
Sorry to hitchhike on your thread. But if the LEDs exceeds the voltage driven by the driver available in the market (ie. 18 x 3W driver). A DIY lightset of 36 pieces of 3W leds does it means it must be driven by two drivers connected in two separate circuits, or is there another way around it.
Inspired by AmanoLimited by Yusof Ishak
yes you need to split it, i.e. 2 driver drive 18 LEDs each.
Yes you need to wire them separately. Most drivers out in the market are build to drive the LEDs in series.
Should you connect more than the recommended number of LEDs, the voltage across each single LED will be lower, and might fail to power on the LED.
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From my experience, DIY the LED lighting for my signage board... With a driver 5A doesn't really throw 5A to your circuit. If lesser load, the current will be smaller.. However, please correct me if I'm wrong...
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you can use series resistor to limit the current but then efficiency will drop.
Hi all, thanks for the guidances. I will be dropping by Sim Lim square for a survey.
I have google on some of DIY LED website, I came across some actually connect the LEDs in parallel.
However, the current consumption will be extremely high. Kindly advise which is more prefer, parallel or series?
As I am actually doing this for my planted tank, do I need to add red and blue LEDs? Or white LED will do? Thanks.
If your driver can only supply up to 5A, it means if can supply only maximum of 5A. However if your load only draws 1A, it means your driver only supply 1A to your load.
Yes, do take note of the power rating of the resistor when you choose the resistor. If your current is 1A and you intent to use a 10ohm resistor, the power rating of the resistor will be 10ohm x 1A = 10 watt. If you use a 5watt resistor, you will burn your resistor.
Most drivers are made to drive the LEDs that are connected in series instead of parallel. If you want to drive your LEDs in parallel, you need to find drivers that are wired to do it that way. However, they may be more expensive as they are not as widely used and produced as compared to those wired for series.
Depending on what you want for your planted tank. You will need to choose the type of LEDs accordingly. LEDs are made to produce specific spectrum which somewhat goes along with the colour of the LED. Thus, to replicate a full spectrum T5HO, some brands of LEDs use up to 6 to 7 different coloured LEDs to cover the whole spectrum ranging from 400 to 700nm.
If you want it to look good to your eyes, 6500K LEDs will be great to grow plants. By great means that they grow very well, and looks natural to your eyes. However the downside of just using 6500K is that there is more focus on the 500nm range, which means green light, which is not so beneficial for plants. It also means that red plants do not turn out as red as compared to T5s due to certain chlorophyll deficiency.
Plants in general do benefit more from the 460nm and 650nm ranges. LEDs for the above are the Royal Blue and Deep Red LEDs respectively. However, using a combination of these although will accelerate plant growth, and produce better reds in plants, it will look unnatural and dim. This is because plants generally absorb the blue and red lights and reflect the green lights, thus making it look green. So when you only shine red and blue light, it will look much darker as most of the light is absorbed and left over lights make your tank look purple.
I will suggest to go for 100% 6500K LEDs and try it out before moving to try out the different spectrums for plant growth.
I am currently experimenting with different colour LEDs and intensities to see how plants react, and the best way to imitate T5HO using LEDs.
You can take a look at Hydra Fifty Two, for their full spectrum LEDs. They do include UV as well. Should you want to view and take a look at it and it's effects on plants, you can look for Alvin as Aquarist Chambers and see the difference it makes on plants.
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Hi qnqwn, thanks for the details clarification. I have decided to go ahead with white light 1W LED, rated 6700K.
Whats the depth of your 4ft tank? If its above 45cm height then maybe consider 3W LEDs instead for better light intensity at depth, especially for carpet plants.
Though if you are only planning to grow low light slow-growing plants with less emphasis on carpet plants, then 1W LEDs would be okay.
Wow in that case I need to choose 3W LED already. My fish tank is 4ftx2ftx2ft
I intend to grow carpet grass. Thanks for the reminder.
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