rabbut
I don't bite, all that often...
Well, many know I've built a DIY LED array, and many have expressed an interest in the nitty gritty details on it. So, without further a-do;
The array is about 2ft by 15", holding 30 LED's in total. That's 15 Blue and 15 White. They are computer controlled with the blues fading on over an hour, before the whites fading on over the hour after the Blues first started. The whites run full tilt then for 8 hours, the Blues at about 2/3 of full power, before the Whites fade down over an hour, followed by the Blues. The top fans, shown below are on from when the Blues start fading on, and remain on for half an hour after they finish fading off, before the computer turns them off for me
There are air in-takes on the opposite side roughly in line with where the LED heat sinks are, to blow the cushion of hot air off the top of the sinks to keep the LED's cooler, as below
The smaller holes are the air in-takes, the large fans are actually air extractors from the main tank's air pocket above it. They should remove hot and humid air from the tank area, after the tank fans have done their stuff. These have an air temperature sensor inside the cabinet that switches them on and off as needed. Likewise the tank cooling fans below, that have a temperature probe in the tank
All the sensing and computing is done inside the "magic box" at the side of my tank, built into the cabinet. In there about 30 wires connect to various bit and bats in part of the rig I fondly refer to as "spaghetti junction", as that's what it look like
I will point out that all those wires are only needed due to the computerised dimming and temperature controlled fans though, for just on and off LED's, you'll probably have a less daunting 5-6 wires to connect up below the rig
*Picture of Spaghetti Junction coming soon...*
So, what gear is essential to making an LED rig?
1) Well, LED's are the obvious one... I'm using third generation Luxeon Star's in Royal Blue and Warm White for my rig, but Cree and Seoul also do suitable LED's that are main-stream, well priced and easy to get. Actually, Cree and Seoul use the same emitters (the bit that makes the light basically) and just package them differently
With Whites, you want ones that emit a full spectrum, not just three prime colours to get white, as the Luxeon Rebles do. Start a new thread if you building your own LED rig and need info on whether the ones you are looking at will work, and someone (not necessarily me, others in FW have build DIY LED's also) will get back to you...
2) Constant Current Drivers. I'm using Black Cat drivers, but Luxeon make Buckpuck's that are suited, as do MeanWell and many, many more manufacturers. Ignore the wattage ratings on drivers when you buy them, look instead at the current rating and maximum voltage, as these are more important to you for working out if they are any good. The Voltage says how many LED's you can run off one driver, and the Current says if they are the correct model for your LED's. The driver's current needs to be slightly less than the LED's maximum current tolerance rating. Again, if that's unclear for your own rig, post your own thread as for the LED's.
3) Heat sinks. Heat is the main killer for LED's so you need to get it away from them. They may be small but they do get warm. The Luxeons "burn out" around 150c, and they'll get that warm without heat sinks within about 15s of running at full power without cooling. I'm using generic computer chipset heat sinks for mine. You need a layer of Thermal Paste between the LED and the heat sink though to transfer the heat to the heat sink better... Many have mounted all the LED's onto a custom made heat sink and mounted the sink over their tank. A few also use "strip light style" heat sinks also...
4) Cooling fans. Unless you are using very big heat sinks, you'll need some fans to blow air over the heat sinks and keep the LED's cool enough to operate. I'm using 12cm Akasa PC case cooling fans, as you can see above
5) What am I missing? Erm... Something essential.... Like, erm.... A power supply? Yer, one or two of those could be useful 
I'm using a Laptop PSU (well two actually), one that can supply an extra 25% of the current needed by your drivers at the Voltage you are running at. Don't run on the edge of what the PSU can do, it will lead to it getting very warm and shortening it's life. A small short somewhere down the like could make this component a fire hazard if under-powered also, so don't skimp here 
Again, if you don't know what you need, post your own thread and ask
Optional Extras
Well, computers can be used to control the LED's if you like, to get nice fade effects, simulate lunar cycles, cloud cover and sunrise/sunset. Arduino project boards, such as the Duemilanove that I'm using and the Mega boards are popular choices for this. They can be programmed in Java rather than machine code, making life a lot easier. See the Arduino home page for more information. Obviously, computer control adds more complication to the rig, and to use the computer to actually dim the LED's. With Buckpuck's, you can feed the Arduino's output directly into the control pin to dim. With mine, I have to use transistors to connect the control pin of my drivers to a common ground whenever the output of the Arduino goes high... This area of actually controlling the dimming is where most rigs get more complex, so I'd strongly advise posting your own thread if dimming is something you'd like on your rig to ensure you have the correct gear to do it before you break something, if anything is slightly un-clear For instance, if I did the Buckpuck "stick the Arduino onto the control pin" on my drivers, I'd fry the LED's and possible the driver, as the control pin is an internal reference, so the "added voltage" from the signal would lead to the LED's being "overdriven", or having too much electricity pushed through them, overheating them and killing them off 
Dimming is actually simple if you know what you are doing with electronics, so don't be too put off by it, but I also understand many people running away screaming at this point
Also, you can use a Variable Resistor (often in the form of a Potentiometer/"Pot", two variable resistors in one, that change in relation to each other) to control the light output. How you wire it up to work depends on the driver you are using, but it essentially acts like a primitive dimmer. On my drivers, you'd wire the common pin to ground and one of the two local pins to the control. You dim your LED's by turning the dial...
There are also other optional extras I've seen people play with, like an in-line resistor on the LED string to warm up the LED's colour output, or applying another voltage to the string to cool down the light out-put. The latter can lead to issues of over-driving again though, and dead/dieing LED's if not done carefully...
What did my rig cost then, and where did I get the stuff?
15 Third Generation Luxeon Star Warm White LED's in the three Watt version. They cost £3.12 each delivered through an Ebay seller. It was a one-off auction however. You can buy direct from Luxeon though
15 Third Generation Luxeon Star Royal Blue LED's in the three Watt version. They cost about £3.50 each delivered through an Ebay seller in another one-off auction. Again, available direct from Luxeon.
6 Black Cat 970mA Constant Current Drivers. These were through an Ebay seller, teap0t42, and cost about £6 each delivered (bulk buy shipping discount applied).
3 RAM heat sinks, cut in half, to cool the drivers (they get warm in use). Cost £4.99 each from Maplins
30 Generic Computer Chipset heat sink, £2.50 each from Ebay seller virtualvillage-uk-rho. (don't use that seller in a rush, postage was slow, but what do you expect from China...)
10ml tube of Thermal Paste £14.99 from Maplins
2 Akasa 120mm Computer Case Cooling fans, £9.99 each from Maplins
*Optional Component* 6 Open Collector NPN Transistors (any type will do), the ones I used cost £1.49 each from Maplins
*Optional Component* 6 470 Ohm Resistors, 11p each from Maplins
*Optional Component* 1 Arduino Duemilanove project board, £28 from Cool Components
*Optional Component* 30 25 degree Lenses to make the LED's beam narrower... About 20p each from Ebay seller auspicious.e The delivery was slow and these lenses required modifications to get them to fit the LED's they were supposed to fit though...
So, that's a total spend of around £308.78 for my new light rig, excluding cooling for the tank and air-gap. One down, one to go for the Discus
After some more saving up 
Control *Optional*
This may be of interest to those folks that want to computer control their rigs, the code from my project...
The commenting should make it self-explanitory to anyone whom has Java coded before. If you haven't copy that into your project when you have the Arduino project and play arround with the numbers to see what they do. As it is, if the Arduino boots at midnight, the fans and Blues come on at 11:30, whites at 12:30, then whites off at 12:30 and Blues at 22:30, with an hours fade from each mentioned point. Note the big jump at fade-on time. This is because Black Cat drivers dim Logariytmically on PWM control from the Arduino, and that jump is required to actually see any light from the LED's when you want them to come on
Sorry for the wall of text and the no doubt evident lack of Proof-reading
Rabbut
Well, I've just proof-read it, corrected a few spelling issues and added a couple of components (the fans) in the parts-cost list that I missed... I've amended the spend accordingly also.
The array is about 2ft by 15", holding 30 LED's in total. That's 15 Blue and 15 White. They are computer controlled with the blues fading on over an hour, before the whites fading on over the hour after the Blues first started. The whites run full tilt then for 8 hours, the Blues at about 2/3 of full power, before the Whites fade down over an hour, followed by the Blues. The top fans, shown below are on from when the Blues start fading on, and remain on for half an hour after they finish fading off, before the computer turns them off for me
There are air in-takes on the opposite side roughly in line with where the LED heat sinks are, to blow the cushion of hot air off the top of the sinks to keep the LED's cooler, as below
The smaller holes are the air in-takes, the large fans are actually air extractors from the main tank's air pocket above it. They should remove hot and humid air from the tank area, after the tank fans have done their stuff. These have an air temperature sensor inside the cabinet that switches them on and off as needed. Likewise the tank cooling fans below, that have a temperature probe in the tank
All the sensing and computing is done inside the "magic box" at the side of my tank, built into the cabinet. In there about 30 wires connect to various bit and bats in part of the rig I fondly refer to as "spaghetti junction", as that's what it look like
I will point out that all those wires are only needed due to the computerised dimming and temperature controlled fans though, for just on and off LED's, you'll probably have a less daunting 5-6 wires to connect up below the rig *Picture of Spaghetti Junction coming soon...*
So, what gear is essential to making an LED rig?
1) Well, LED's are the obvious one... I'm using third generation Luxeon Star's in Royal Blue and Warm White for my rig, but Cree and Seoul also do suitable LED's that are main-stream, well priced and easy to get. Actually, Cree and Seoul use the same emitters (the bit that makes the light basically) and just package them differently
With Whites, you want ones that emit a full spectrum, not just three prime colours to get white, as the Luxeon Rebles do. Start a new thread if you building your own LED rig and need info on whether the ones you are looking at will work, and someone (not necessarily me, others in FW have build DIY LED's also) will get back to you...2) Constant Current Drivers. I'm using Black Cat drivers, but Luxeon make Buckpuck's that are suited, as do MeanWell and many, many more manufacturers. Ignore the wattage ratings on drivers when you buy them, look instead at the current rating and maximum voltage, as these are more important to you for working out if they are any good. The Voltage says how many LED's you can run off one driver, and the Current says if they are the correct model for your LED's. The driver's current needs to be slightly less than the LED's maximum current tolerance rating. Again, if that's unclear for your own rig, post your own thread as for the LED's.
3) Heat sinks. Heat is the main killer for LED's so you need to get it away from them. They may be small but they do get warm. The Luxeons "burn out" around 150c, and they'll get that warm without heat sinks within about 15s of running at full power without cooling. I'm using generic computer chipset heat sinks for mine. You need a layer of Thermal Paste between the LED and the heat sink though to transfer the heat to the heat sink better... Many have mounted all the LED's onto a custom made heat sink and mounted the sink over their tank. A few also use "strip light style" heat sinks also...
4) Cooling fans. Unless you are using very big heat sinks, you'll need some fans to blow air over the heat sinks and keep the LED's cool enough to operate. I'm using 12cm Akasa PC case cooling fans, as you can see above
5) What am I missing? Erm... Something essential.... Like, erm.... A power supply?
Yer, one or two of those could be useful I'm using a Laptop PSU (well two actually), one that can supply an extra 25% of the current needed by your drivers at the Voltage you are running at. Don't run on the edge of what the PSU can do, it will lead to it getting very warm and shortening it's life. A small short somewhere down the like could make this component a fire hazard if under-powered also, so don't skimp here Again, if you don't know what you need, post your own thread and ask Optional Extras
Well, computers can be used to control the LED's if you like, to get nice fade effects, simulate lunar cycles, cloud cover and sunrise/sunset. Arduino project boards, such as the Duemilanove that I'm using and the Mega boards are popular choices for this. They can be programmed in Java rather than machine code, making life a lot easier. See the Arduino home page for more information. Obviously, computer control adds more complication to the rig, and to use the computer to actually dim the LED's. With Buckpuck's, you can feed the Arduino's output directly into the control pin to dim. With mine, I have to use transistors to connect the control pin of my drivers to a common ground whenever the output of the Arduino goes high... This area of actually controlling the dimming is where most rigs get more complex, so I'd strongly advise posting your own thread if dimming is something you'd like on your rig to ensure you have the correct gear to do it before you break something, if anything is slightly un-clear
For instance, if I did the Buckpuck "stick the Arduino onto the control pin" on my drivers, I'd fry the LED's and possible the driver, as the control pin is an internal reference, so the "added voltage" from the signal would lead to the LED's being "overdriven", or having too much electricity pushed through them, overheating them and killing them off Dimming is actually simple if you know what you are doing with electronics, so don't be too put off by it, but I also understand many people running away screaming at this point Also, you can use a Variable Resistor (often in the form of a Potentiometer/"Pot", two variable resistors in one, that change in relation to each other) to control the light output. How you wire it up to work depends on the driver you are using, but it essentially acts like a primitive dimmer. On my drivers, you'd wire the common pin to ground and one of the two local pins to the control. You dim your LED's by turning the dial...
There are also other optional extras I've seen people play with, like an in-line resistor on the LED string to warm up the LED's colour output, or applying another voltage to the string to cool down the light out-put. The latter can lead to issues of over-driving again though, and dead/dieing LED's if not done carefully...
What did my rig cost then, and where did I get the stuff?
15 Third Generation Luxeon Star Warm White LED's in the three Watt version. They cost £3.12 each delivered through an Ebay seller. It was a one-off auction however. You can buy direct from Luxeon though
15 Third Generation Luxeon Star Royal Blue LED's in the three Watt version. They cost about £3.50 each delivered through an Ebay seller in another one-off auction. Again, available direct from Luxeon.
6 Black Cat 970mA Constant Current Drivers. These were through an Ebay seller, teap0t42, and cost about £6 each delivered (bulk buy shipping discount applied).
3 RAM heat sinks, cut in half, to cool the drivers (they get warm in use). Cost £4.99 each from Maplins
30 Generic Computer Chipset heat sink, £2.50 each from Ebay seller virtualvillage-uk-rho. (don't use that seller in a rush, postage was slow, but what do you expect from China...)
10ml tube of Thermal Paste £14.99 from Maplins
2 Akasa 120mm Computer Case Cooling fans, £9.99 each from Maplins
*Optional Component* 6 Open Collector NPN Transistors (any type will do), the ones I used cost £1.49 each from Maplins
*Optional Component* 6 470 Ohm Resistors, 11p each from Maplins
*Optional Component* 1 Arduino Duemilanove project board, £28 from Cool Components
*Optional Component* 30 25 degree Lenses to make the LED's beam narrower... About 20p each from Ebay seller auspicious.e The delivery was slow and these lenses required modifications to get them to fit the LED's they were supposed to fit though...
So, that's a total spend of around £308.78 for my new light rig, excluding cooling for the tank and air-gap. One down, one to go for the Discus
After some more saving up Control *Optional*
This may be of interest to those folks that want to computer control their rigs, the code from my project...
Code:
// Marine Tank LED fading on/off program
// By Rabbut on Tropical Fish Forums
// Written on 17/06/2009
int bluevalue = 255; // Variable to keep the actual level for the Blue LED's
int blueledpin = 9; // The Blues are connected to digital pin 9
int whitevalue = 255; // variable to keep the actual level for the White LED's
int whiteledpin = 3; // The Whites are connected to digital pin 3
int fanpin = 2; // The Fans connected to digital pin 2
void setup()
{
pinMode(fanpin, OUTPUT); // Set-up the Fan pin
digitalWrite (fanpin, LOW); // Turns the Fans off
analogWrite(blueledpin, bluevalue); // Sets the correct level to the Blues
analogWrite(whiteledpin, whitevalue); // Sets the correct level to the Whites
}
void loop()
{
delay (41400000);
digitalWrite (fanpin, HIGH); // Turn on the Fans
for(bluevalue = 20; bluevalue >= 8; bluevalue-=1) // Fade in the Blues at Eleven Thirty
{
analogWrite(blueledpin, bluevalue); // Sets the new level to the Blues
delay(276923); // Waits Five minuites before incrementing the output further, for a 1 hour fade time
}
delay (12);
for(whitevalue = 20; whitevalue >= 0; whitevalue-=1) // Fade in the Whites at Twelve Thirty
{
analogWrite(whiteledpin, whitevalue); // Sets the new level to the Whites
delay(171428); // Waits Three minuites before incrementing the output further, for a 1 hour fade time
}
delay (1);
delay (28800000); // Wait for Eight hours before starting to fade off the Whites
for(whitevalue = 0; whitevalue <= 20; whitevalue+=1) // Fade out the whites at Nine Thirty
{
analogWrite(whiteledpin, whitevalue); // Sets the new level to the Whites
delay(171428); // Waits Three minuites before incrementing the output further, for a 1 hour fade time
}
delay (12);
analogWrite (whiteledpin, 255);
for(bluevalue = 8; bluevalue <= 20; bluevalue+=1) // Fade out the Blues at Ten Thirty
{
analogWrite(blueledpin, bluevalue); // Sets the new level to the Blues
delay(276923); // Waits Five minuites before incrementing the output further, for a 1 hour fade time
}
delay (1);
analogWrite (blueledpin, 255);
delay (1800000); // Wait half an hour until Midnight
digitalWrite (fanpin, LOW); // Before turning the Fans off and re-starting the loop
}The commenting should make it self-explanitory to anyone whom has Java coded before. If you haven't copy that into your project when you have the Arduino project and play arround with the numbers to see what they do. As it is, if the Arduino boots at midnight, the fans and Blues come on at 11:30, whites at 12:30, then whites off at 12:30 and Blues at 22:30, with an hours fade from each mentioned point. Note the big jump at fade-on time. This is because Black Cat drivers dim Logariytmically on PWM control from the Arduino, and that jump is required to actually see any light from the LED's when you want them to come on
Sorry for the wall of text and the no doubt evident lack of Proof-reading
Rabbut
Well, I've just proof-read it, corrected a few spelling issues and added a couple of components (the fans) in the parts-cost list that I missed... I've amended the spend accordingly also.
. I tried to imagine what it would look like in assembler, I would have to sit down with pen and paper for that one 
