DIY 10-CREE LED Light

[nikochan]

Wow! this is very impressive! hmm.. is it even worth making a 1Cree LED for my cube tank?

[Splutter]

Sigh I also wanted the hardscapes to be slightly taller but I can't find any suitable ones and I just didn't have the time to wait anymore.

nikochan, I think it's not really that worth it unless you are modding some existing lighting fixture. This DIY isn't exactly cheap, I'm doing it more for the fun of it =)

[sufan]

Wow, I absolutely love your DIY LED lights. They actually looks very professional custom made unit. The only suggestion that I have is that the metal sheet would look much better if it was made from mirror polished stainless steel. I have a questions, do you think you get enough light for the tank from the LED? If so, what the equivalent of the TL in wattage?

[Navanod]

Bro sufan, that metal sheet of aluminum doubles as a heatspreader. Stainless steel would not be as good for that purpose.
Aluminum can also polish to a mirror though, haha, if splutter had the elbow grease to do it

[Inwares LED]

very nice craftmanship! looks very bright. Will the fishes go blind or not? hehe...juz kidding.

[Matt.Lee]

Bro Navanod,
Why not use copper sheet? It is also use as a CPU heatsink in our computers. Surface can be polish to shine.

[Splutter]

I did try to polish the aluminum plate, but I think I made it worse, haha. It's definitely possible to make aluminum shine, but you'll need a orbit sander and it'll probably take a good 4-5 hours of polishing still. Copper works too I guess but you'll have yellowish lighting due to the reflections, besides copper oxidises pretty easily and the shine won't last. Not to mention copper is extremely toxic for shrimps/snails if water somehow gets in touch.

The lighting isn't as glaring as I thought it'll be, probably due to the height of the tank and some oil at the surface diffusing the light. I actually bought reflectors as well but didn't use them in the end as it caused hotspots.

I was hoping to see some pearling from my moss, but that didn't happen. I'm pretty new to this hobby so can anyone advice if this is due to mosses not pearling in general or is it due to other parameters like no CO2 etc?

[Navanod]

Bro Navanod,
Why not use copper sheet? It is also use as a CPU heatsink in our computers. Surface can be polish to shine.

Oxidation of the copper would turn it green in no time! and it more expensive

I did try to polish the aluminum plate, but I think I made it worse, haha. It's definitely possible to make aluminum shine, but you'll need a orbit sander and it'll probably take a good 4-5 hours of polishing still. Copper works too I guess but you'll have yellowish lighting due to the reflections, besides copper oxidises pretty easily and the shine won't last. Not to mention copper is extremely toxic for shrimps/snails if water somehow gets in touch.

The lighting isn't as glaring as I thought it'll be, probably due to the height of the tank and some oil at the surface diffusing the light. I actually bought reflectors as well but didn't use them in the end as it caused hotspots.

I was hoping to see some pearling from my moss, but that didn't happen. I'm pretty new to this hobby so can anyone advice if this is due to mosses not pearling in general or is it due to other parameters like no CO2 etc?

I think I saw the spiral polishing marks on the plate in one of the pic! hahaha!
I just got my XP-G R4 torchlight and did an estimate. It can only cover 1/12 of my 2x1.5 tank surface. But then again, its kinda underpowered as its on batteries. Now to save up for that DIY project

Bro, for pearling to happen, you need stable CO2 injection at 30ppm. Otherwise, blasting lights into the tank will only grow algaes

[Matt.Lee]

Bro Splutter,
Where did you buy these 10Ohms 10W resistors, cost? From your picture, they look like ceramic power resistors?

[Splutter]

Hi Bro,

Can get them at most shops in Sim Lim Tower. Should be around $2 for 1.

[madi]

wah... nice.. now i know the easier way to power up LED... hahaa.. for now i'm using this circuit to limit the current..
http://www.instructables.com/id/Supe...3/Assemble-it/

[jamesneo]

I have a noobie technical question.
I have a typical AC to DC adaptor with a output DC 12V and 0.8A.

Cree LED spec:
- 3.7V typical driving voltage
- Manufacturer Rated 228 Lumens at 1000mA input current:
350mA: 107~114lm
700mA: 171.2~182.4lm
1000mA: 214 ~ 228lm

1) Can i use this to power up say 5 CREE LEDs since the specs say it has only 3.7V driving voltage?
2) Why do we need to use the LED driver since the AC to DC adaptor have a rating spec which could do the job?
3) I just saw my notebook power cord AC to DC adaptor output as 19V, 4.22A, This is more than sufficient to drive 10 CREE LEDs?
4) A typical 36W PL light lumen output is 2800 Lumen. If the LED CREE lumen is 228lumen, so i have to buy about 2800/228 = 12 LED to achieve 2800 Lumen?
5) A 36W PL cost $10 while 12 CREE LEDs will cost S$80, isn't it more expensive ???

Thanks

[neverwalkalone]

James, I'm not an expert in this area, but if I may give some inputs:

I have a typical AC to DC adaptor with a output DC 12V and 0.8A.
1) Can i use this to power up say 5 CREE LEDs since the specs say it has only 3.7V driving voltage?

5 LEDs in series will be 5x3.7V = 18.5V, not enough from your 12V adaptor to drive; so the max you can go with this 12V adaptor is 3 LEDs (max out at 800mA). Having said that, I would not encourage you to use just an AC-DC adaptor without additional electronics for this purpose (as much as some of the shops at SimLimTower are telling you it's fine to do so)...

2) Why do we need to use the LED driver since the AC to DC adaptor have a rating spec which could do the job?

Strictly speaking, LED drivers are (constant) CURRENT supplies, which ensures that the LEDs are driven with the same current (limited). What you see in most simple designs (eg instructables.com,) are using voltage supplies, which is not ideal, but gets the job done.[/QUOTE]

3) I just saw my notebook power cord AC to DC adaptor output as 19V, 4.22A, This is more than sufficient to drive 10 CREE LEDs?

Again, going back to #1, you could potentially wire up 2x5LEDs in parallel, which the 4.22A can easily drive; but I wouldn't do this if I were you. The parallel circuit will need some form of 'current balancer' to keep the currents in the 2 LED strings the same, so that it won't damage the LEDs in the event an LED blows/shorts. You can get it to work with a simple circuit, but it's not safe, nor power efficient. You seem to have done some reading on the LEDs, (amperage/lumens etc), I suggest additional reading on the LED driver circuitry, even if you're not a techie. It should not be too complicated beyond Sec2 Physics, unless you're into designing from scratch with transistors. ;-)

4) A typical 36W PL light lumen output is 2800 Lumen. If the LED CREE lumen is 228lumen, so i have to buy about 2800/228 = 12 LED to achieve 2800 Lumen?

Looking at lumens alone is not the best measure of "effectiveness" of the lights. I suggest you google search the differences between the aquatic lighting solutions and understand what I'm saying. PAR (or PUR) is the more accurate measure, but most (all?) of us have no access to such. Suffice to say, LED lights are more "effective" than other lights, which explains why the trend towards them. For all intended purposes, 6-8 (3W) LEDs will probably be enough to replace a single 36W PL lamp (assuming its to light a 2x1x1' tank)

5) A 36W PL cost $10 while 12 CREE LEDs will cost S$80, isn't it more expensive ???

LEDs are still considered fairly 'new' technology, and it will still be more expensive (though the prices are falling quickly, capabilities [eg brightness/lumens-watt] improving). You need to ask yourself why you're going to use LEDs - environmentally friendly (no mercury FLs to dispose), less power consumption (though at 36W, your $s saved is probably minimal), less heat, dimmer control, colour variety [eg moonlight blue] etc etc.

If it's purely a $s decision, I'd say the PL lights (at 36W) is still a much cheaper option. But like all technologies, expect this to be a viable option in the near future. You can already see alot more LED lamps for both normal use and specifically Aquatic lighting.
Hope this helps.

Cheers

[jamesneo]

Hi neverwalkalone,

Thanks for your great info. You have answered all my queries.
Cheers.

[Splutter]

Hi James,

Just to add on. LEDs will have a throughput current based on the voltage that's across it. It is very very important to make sure that the voltage across the LED doesn't exceed the specifications or the current though the LED will shoot up exponentially. When this happens, either the LED blows or your power supply overloads and blows. Thus, it is necessary to have a resistor in series to limit the max current. Hope this helps.

[jamesneo]

Thanks Splutter. Will keep that in mind when planning for the DIY.
For the time being (after doing all the calculations), it's not within my budget at the moment.

[briandang]

So anyway, I ditched the idea of using this voltage regulator as the output voltage wasn't very stable. As I was running the circuit without any current limiting resistor, it led to unstable current load as well. The regulator died out after a while. I went back to the drawing table and opted for a dual AC/DC switching supply instead where I hooked up 5 LEDs + a resistor to a single regulator at 24v, 700mA.


Some of my calculations:

Voltage drop across 1 LED at 700mA = 3.5v
Voltage drop across 5 LEDs at 700mA = 5 x 3.5 = 17.5v
Voltage across resistor required = 24v - 17.5v = 6.5v
Resistance of resistor required = 6.5v/700mA = 9.285ohms
Wattage of resistor required = 6.5v x 700mA = 4.55w

Resistor eventually used : 10 ohms, 10 watts as I wanted to be on the safe side for heat dissipation

I also bought 2 new Mean Well switching regulators at SLT again.


Wired up everything according to this circuit diagram:

can i check with you that can i use a swith with 5A not only 700 mA as your design cause if you buy 1 save your cost as well. As i know that with 5 A can supprt to 07 mA each.
pls correct if i wrong.

[Splutter]

Hi,

I'm not sure exactly what you are asking about but the switch used is rated up to 13A. You can of course use just one if you are sure the fan is going to be on all the time, I wasn't so sure back then so I got another just in case I didn't always needed the fan. Regarding cost savings, it's not going to be much since the switch is just $1.

[briandang]

oh. i mean it is AC DC Switching? not the switch as you mean.

[neverwalkalone]

Briandang,
I wouldn't advice using too high (5A) a rated supply if you are to follow brother Splutter's circuit, as there is really very little protection against a runaway current in this design (no offense to brother Splutter); ie imagine a 'worst case' scenario of the full 24V applied across the resistor (assume all LEDs shorted/have zero voltages), that'll be 2.4A! (24v/10 Ohm) - in his case, he is using a 700mA limit on the meanwell, so that is the limit the LEDs will get, preventing damage potentially.

Ideally, the DC supply should be going into a "buck" regulator, which will ensure a CONSTANT CURRENT to the LED string regardless of the voltage drops (which will vary as the temperature changes in the LEDs).

Using a much higher amperage supply will imply that potentially your circuit can reach that upper limit, which is dangerous. There are a number of DIY LED project threads on our forum alone, and bro EdwardChuaJH has done a very good writeup on his project. I urge you to study them (and the many others available online) before designing/wiring your circuit for safety reasons.