DIY LED Using 10 Watt Arrays

[Tony Ooi]

i was trying to understand the whole circuitry from all the post here.
Sorry i have few quick questions as i trying to follow these post and make sure i get the correct understanding
In the end, you didn't have any resistor in series with each LED, right?
The whole circuitry is just the 12V power go into the dimmer and from dimmer go to the LED. Please correct me if i am wrong.

[mike31154]

Originally Posted by Tony Ooi

In the end, you didn't have any resistor in series with each LED, right?
The whole circuitry is just the 12V power go into the dimmer and from dimmer go to the LED. Please correct me if i am wrong.

You are absolutely correct. The two 12 VDC power supplies have a limited range of adjustment via a small potentiometer next to the wire terminals. The adjustment range is from about 10 volts to 13 volts. Downstream of the power supplies are the manual dimmers which provide further control & enable me to dim all the way to off.

The LEDs are all hooked up in parallel, no series chains whatsoever. If one of the LEDs were to burn out, the remainder on that dimming circuit would likely run at a slightly higher current which poses a certain risk if I don't notice for a while. I mitigate that risk by having the manual dimmers adjusted to 8.5 VDC, which is 1/2 volt below the recommended minimum forward voltage of my 455nm Royal Blue LEDs (spec for them says Vf should be 9 to 10 volts). So in essence, I am slightly underdriving the Royal Blue LEDs. The whites, 10000K & 6000K as well as the 470nm blues can handle a higher Vf (up to 12 VDC) so they are underdriven even more. In addition, each LED has its own fan for cooling, which adds to the safety factor with respect to burn outs.

I opened up a couple of the dimmers to see what makes them tick since there is little info on them other than the rated input/output. Some of the vendors selling them on eBay talk about them being pwm and/or constant current capable but it sure would be nice to confirm how they really work. Aside from the potentiometer, the dimmer consists of solid state circuitry including what looks like a MOSFET transistor, so they do have some complexity. Despite the low price, the soldering & assembly are very good quality.

[Tony Ooi]

Thansk for your explanation.
Te 12V DC power supply, the potintiometer you mention , is it the the plastic which have philips screw head?
my dimmer just arrived yesterday. I have yet to open up to inspec what is inside , but it felt like almost nothing and very light wieght. I have LED which spec at 10watts(running at 10V, 1A current). Theoretically should able to handle up to 8 LED per dimmer base on the label stated there 8A. For safety reason, i might just want to keep 6-7 LED per dimmer.

[mike31154]

Originally Posted by Tony Ooi

Thansk for your explanation.
Te 12V DC power supply, the potintiometer you mention , is it the the plastic which have philips screw head?
my dimmer just arrived yesterday. I have yet to open up to inspec what is inside , but it felt like almost nothing and very light wieght. I have LED which spec at 10watts(running at 10V, 1A current). Theoretically should able to handle up to 8 LED per dimmer base on the label stated there 8A. For safety reason, i might just want to keep 6-7 LED per dimmer.

On both my power supplies the adjustment potentiometer is as you describe, located next to the power supply power "ON" indicator LED. If you look at the photo on post #46 closely, you should be able to see it on the left of the power supply front panel. It's the only adjustment that is accessible from the outside of the power supply.

Definitely a good idea to keep the number of LEDs per dimmer below 8 as you plan to do. Having said that, the dimmer controlling my 10000K LEDs is doing fine with 10 of them hooked up. Of course I don't run them at full voltage/current, but it reminds me that it might be a good idea to add one more dimmer! Seems to me when I first ran the fixture one of the dimmers had both the 10000K & 6000K on it, meaning a total of 14 LEDs plus the cooling fans! No issues, but I don't know what I was thinking & certainly wouldn't recommend that, even though I had the voltage down at 4 to 5 volts.

[mike31154]

A few additional photos showing the 5050 SMD LED RGB strip lighting I recently added to the fixture. Since I don't have a controller running the 10 watt chips, I'm using the RGB strips selected to blue on a timer to provide a crude dawn/dusk effect. I suppose I could have simply purchased a straight blue strip instead of RGB, but the cost difference is minor & it's interesting to play with the different colour combos possible with the IR remote control pad & the RGB strip.

Close up of the strips mounted along the center rail of 10 watt emitters. I simply drilled/threaded the center rail alumiunum angle in 4 locations & used small stainless steel screws to attach the angle holding the LED strips.


This shows a bit more of the fixture with the blue LEDs shining.


Now for some shots over the tank with different colours. Blue, red, violet/purple and white (using all 3 colours). I've left out the green since it's not a colour one would normally use on it's own over a marine tank. Photos are all with respective LEDs at full power. They can be dimmed down to near zero with the 44 key remote control.








As you can see the 'white' shot lights up the tank fairly well with the 2 rows of 5050 SMD LEDs at full brightness. Each row sports 63 LEDs in segments of 3 for a total of 126 LEDs. I have 174 LEDs left on the spool to use on another project. Someone with a FOWLR could easily build a suitable fixture using additional rows of these. Could even work for a tank with softies & LPS. You'd have to mount them fairly low & pack a bunch of rows together, but the stips are available with various levels of water proofing, so that shouldn't be an issue. There are brighter 5630 SMD strips available, as well as less bright 3528 SMD strips. A fairly simple diy to either build a full fixture, supplement existing lights or dawn/dusk effect which is what I use them for.

[mseepman]

Just to comment, I brought in 4 x 50cm strips of the 5630 Samsung LEDS in cool white and they are very very bright. They came mounted on a thin aluminum strip with a surrounding aluminum mount and after running for 5 minutes you would be burned by the aluminum strip. The surrounding mount is still fairly cool. Mounted to a proper heat sink, these would shed a lot of light! Haven't seen them in any colours or RGB yet.