Planted Tank Enthusiast
Join Date: Aug 2009
Location: Vancouver, WA, USA
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Gotta know the lingo! If you know something that belongs here, or have a clearer definition for some of these things as they apply to LED’s, help me add to this list!
Decide what aspect of this light is most important for you. Some will prefer a clean build with professional-grade components. Some will just want an inexpensive fixture that works. Some need an all-in-one package. Click on one of the links below, and it will show you the relevant post, and hopefully put you on the right track. Not all posts are represented here, but I will add to this list as the thread grows.
Parts and all-in-one packages are available through many vendors. Below is a list of online vendors who provide one or more component of a build. You can also check and compare prices with each of these websites.
Please help me add to this list!
*Some of these are international sites, some are continental USA. Use your own discretion!
You should start by figuring out the right number of emitters in the best layout to provide the most even PAR coverage in the largest volume of your tank. LEDs emit light in a cone, so the closer to the emitter, the smaller the area lit. (See Optics for more info on beam angle.) The PAR may be different for each individual emitter of the same type depending on binning.
These are links to the manufacturer's data on some popular LED's. For the Cree website, the LED model page contains a link to the data sheet.
Bridgelux BXCD 45
Bridgelux BXCD 50
Bridgelux BXCD 60
Important specs to know about your Emitters (in no particular order)How many for my tank?
Flux or approximate PAR
Hoppy has done a lot of the hard work for us in this department. Here is a link to his thread, which includes a Microsoft Excel Calculator to determine how many of a particular emitter you need to provide adequate coverage for your tank. The most updated version of the calculator is attached in post #14.What colors do I need?
Here is some info from Hoppy on how he uses the calculator:
Quote:Originally Posted by HoppyQuote:Originally Posted by Hoppy
Color temperature is largely a matter of your personal preference, but some suggest that selectively combining particular color temps will provide better growth. Remember that the colors we perceive in the plants are colors that ARE NOT absorbed and used for photosynthesis, so eliminating these colors will make your plants look gray and drab, though they may yet be healthy. Remember that color temp preference is largely based on PERCEPTION, and is very subjective.
White emitter colors typically fall into three categories: warm, neutral, and cool. Warm is a lower color temperature that appears more amber or yellow in color, neutral appears natural and balanced, and cool provides a higher temperature bluish look. It has been said that natural light is closest to about 3500K (we have a “yellow” sun). For a good balance of plant health and aesthetics, some choose a combination of 6500K (cool white) and 4500K (neutral white) emitters. Others prefer a “crisp” or bluer look, and add 10,000K or “Royal Blue” to the mix. Some vendors offer more specific color combos, but these lead to their own challenges. (See “What is the disco effect?” for more info on these challenges). Ultimately, the choice is left to individual preference.
Here is a link to spectral data for some different emitters.Does it matter which brand I get?
Ok, well, let’s address the loudest voices first.
1. There will always be “fanboys.”
2. Most (if not all) LED’s are produced in China.
These are facts of our global economy. Ultimately, you will choose the emitters that satisfy your needs best. Cheap? eBay. Midrange price? Aquastyle carries Bridgelux LED’s for $2.50 each, shipping not included. Steve's LEDs carries Phillips emitters for a similar price. Popular brand name? Crees are widely available and well documented. Remember that price is determined by production costs, shipping, and market demand. If it’s cheaper, there is likely a reason (though this does not necessarily mean they are crap). The most important element: Be sure you are comfortable with that compromise before you buy.
This will depend on several things: What emitters are you using? What current are they running at? What height are they from the substrate? What are the dimensions of your tank? What PAR are you trying to achieve? What optics are you using? Fortunately, Hoppy has done the work for us with his Excel Calculator.What pattern works best?
Pattern isn’t as important as spacing - unless you are blending different colors. Whatever pattern you use, even spacing of emitters will provide the most even coverage. To avoid cool/hot spots, make sure the emitters are evenly spaced in all directions. Consistent patterns with blended colors will limit bizarre shadow patterns and disco effects.How do I get the best shimmer effect?
Fewer emitters = stronger shimmer, but watch out for spotlighting!What is spotlighting?
Spotlighting occurs when there are not enough LEDs to fully saturate an area with even coverage of light. This results in areas of intense light surrounded by areas of less intense light creating bright spots. If this in itself doesn’t bother you, know that is will likely lead to plants “leaning” toward the more intense light cones, and possibly insupportable PAR in the dim areas. While completely eliminating spotlighting by cramming a fixture with emitters is possible, it is quite a bit more expensive than simply calculating the minimum necessary for even coverage for your particular tank, and spacing the emitters appropriately.
Remember to think 3-dimensionally!What is the disco effect?
The beam spread of an emitter crates a cone of light that is narrower at the top than it is at the bottom. Your plants fill the full 3-dimensions of your tank, so you may not be spotlighting the bottom, but the top could have dark and bright spots, leading to plants leaning near the surface of your tank. Work for close to even coverage from the substrate all the way to the surface! Here is a great example diagram testing several layouts for coverage that provides a great 3-D picture of what the light cones look like.
Reefers talk about the “disco” effect. This happens when you use multiple colors that are spaced too far apart, or spaced unevenly or in different quantities.
LED’s are different from fluorescent lamps. Fluorescents produce a diffused, largely even spread of light in every direction from a relatively large surface area. LED’s are what is referred to as “point source emitters” meaning that the light is produced by a very small surface area. This creates a crisper, more focused light that renders very sharp shadows and a cone-shaped area of highly focused, intense light.
If you have a red light and a green light striking an object from different angles, the area lit by both lights will appear “white”, and the shaded areas will appear in bolder colors. Adding a red light to the green side and a green light to the red side will help, but the positional difference will still result in “disco” colors in the shaded areas. The more colors you use, the more colors you will see in the shadows. Cree has produced a "3-up" star that is supposed to limit the impact of this effect by placing 3 emitters in popular color combinations on the same star.
Here is a picture that demonstrates an example of what disco looks like:
Photo from: http://artcation.com/olafur-eliasson...n-gropius-bau/
Optics include a lens that bends and focuses the light into a smaller, more concentrated cone. Reflectors include a shiny surface that bounces the light in another direction.Do I need them? If so, which ones do I need?
Optics limit the beam spread of an emitter. Most emitters have a beam spread of about 120 degrees. Optics come in many beam spread options including 40, 60, 80, 90 degrees, and others. The particular beam spread you use will depend on your preference in fixture height, spacing, tank size, and how you plan to keep the light out of the viewer’s eyes.Will reflectors increase my PAR?
High-power LED’s are dangerously bright. Most of us view our lights from below the level the fixture is hung from. If you don’t consider how you will limit spillover, you could harm yourself or others with these very bright emitters. If you are building an enclosure for your fixture, this may not be an issue.
Hoppy has mentioned that reflectors do not appreciably increase PAR from the emitters.What optics do you recommend?
A lot of all-in-one packages use 60-degree optics. My own fixture uses these as well.
You need a driver. It converts the power from the AC outlet (US) to a DC current, and lowers and regulates the current to a useable level for our emitters. Your options are vast in this department, and so are the prices.
Good with electronics and feeling brave? DIY one! For someone familiar with building circuits, this is a fairly simple build. O2Surplus has generously provided some links here that can get you started. More info on DIY drivers and such:
DIY PCB's for DIY LED Systems
SmartyCat: O2Surplus' ultimate all-in-one driver/controller (now complete!)
For a newbie, you may be better off with an off-the-shelf variety such as a MeanWell or Inventronics dimmable driver.
Either way you choose to go, there are two important specs you need to know about your driver: current, and DC output voltage.
The idea is to get a driver (or drivers for larger builds) that can adequately power the emitters you wish to use. This is where things get technical. Check the max current of your emitters. It’s measured in amps or milliamps (mA). Some can handle up to 1700mA or more, others are more limited. The life expectancy of, and the amount of light emitted from an LED are both largely dependent upon the current at which they are operated. Lower the current, and you lower the operating temperature and the light emitted. Increase the current, and you increase the operating temperature and light emitted. Higher operating temperatures decrease the life expectancy of an emitter (for more info on temperature see: heat sink).
The most efficient way to increase the life span of an LED is to purchase an emitter that is rated with a higher current (ex: 1200 mA) and run it with a driver that provides less current (ex: 650mA). This will allow you to have good light with lower running temps, and your LEDs will last longer. You can also purchase a better heat sink for passive cooling, or add active cooling such as a fan, etc. Some drivers (such as the popular MeanWell drivers) have an adjustment knob that you can (and should) use to lower or raise the current.
Forward voltage is the amount of voltage dropped after passing through an LED. After dropping all of the provided voltage, a dimmer can power no more emitters. The driver’s voltage rating determines how many LEDs you can power using that particular driver. How to figure this out? Add up the forward voltage of your emitters. If it is more than the DC output voltage provided by the driver, then either subtract emitters until you have a value under the driver’s voltage rating and get another driver to power the rest, or find a driver with a higher DC output voltage rating.
IMPORTANT: because the forward voltage on each emitter can vary quite a bit, allow yourself 2-3 volts for margin of error. This will help avoid problems after wiring your circuit.To dim? Or, not to dim?
Depends on how fancy you want to get. The benefits of adding a dimming function are the ability to adjust and fine-tune light output to attain a specific PAR value, and the ability to program your fixture to do fancy tricks.What can PWM dimmers do?
There are commonly two different ways to dim LED’s. One is Pulse Width Modulation, or PWM. This method uses an electronic controller to pulse the emitters very rapidly to achieve different perceived levels of intensity. Another is through controlling the current manually within a specific margin.
To achieve fancy controlled effects using programmable controllers, one can use a dimmable driver compatible with PWM dimming. Using a controller you could program your lights to fade in at dawn, and fade out at dusk. You could program a noon burst to give your plants an extra midday push. You could get really fancy if you have some coding experience and program an Arduino to create a “storm” sequence with changing light to simulate clouds and even flashes of lightning, and control of misters or a drip irrigator to produce a rainstorm. Add a sound system with recorded thunder, and it would be like living in the Amazon. Or the produce section at Safeway. Talk about production value!What is the alternative to PWM?
Here is a thread by sink and O2Surplus, who paired up and went crazy with a DIY driver and an Arduino, and created a phenomenal code that produces great dimming simulations.
You could keep it simple by purchasing a 1-10v dimming driver and just wire in some potentiometers to adjust it manually. There are also available analog controlers that will function much the same as the digital controllers mentioned before. Either would allow one to dial in a specific PAR value (using a PAR meter for reference) allowing flexibility in hanging height and more accurate light control.
Common usage sets the standard, but a “heat sink” when referring to LEDs is actually a heat conductor that absorbs the heat from the functioning emitter, and transmits it to the air over a large surface area (hence the fins) relatively quickly. However, the term “heat sink” has become the popular nomenclature, and thus, we are stuck with it.What can I use as a heat sink?
The heat sink is the foundation upon which you will build your LED fixture. It is more than just a mode of conducting heat away from the LED to prolong its life and preserve your investment; it is the structure that carries your emitters, wiring, active cooling system, and any aesthetic or practical touches like housing or splashguards. It is also a place where you have one of the widest margins of cost difference. Aluminum does a fabulous and inexpensive job of this.How much does a good heat sink cost?
For a 4-foot tank, you can go cheap and marginally functional at around $20 (1/8” flat aluminum bar stock no fins). This material can be found at any big-box home improvement store, or hardware store. It has been posited that running high current emitters at a lower current reduces the amount of heat that needs to be conducted, and a simple aluminum bar can do the job sufficiently. It has also been posited that fins or active cooling are necessary to keep operating temps within optimal specs for longest emitter life. An engineer would need to chime in here to help settle this one - let the games begin!How do I attach the emitters to the heat sink?
Conversely, you can go “pro” with a fancy designer heat sink to the tune of a couple hundred dollars – no joke. These are available through MakersLED and they are pretty amazing but carry an equally amazing price for the larger pieces. They come equipped with cooling fans for every 12" of length and are available in multiple lengths.
The mid-grade choice is a wide selection of finned heat sinks in many sizes and shapes that are reasonably priced for what they provide: a great foundation for a good-looking fixture that functions very well. Heat sinks are available anodized or bare aluminum, pre-drilled and tapped or raw. They are available through some of the all-in-one vendors like RapidLED, LEDgroupbuy, and Aquastyleonline or individually through sites like Heatsinkusa.com.
There area few different ways to attach emitters to the aluminum heat sink of your choosing. Some are considered to be better than others, but all are effective to some degree or another.
For this technique, you would plot your layout pattern on your heat sink, and then drill holes in the heat sink, which would be tapped to receive screws or bolts. For this to work without risking creating a short from your wires to the heat sink itself via the screws, you need to use insulating washers. To improve heat conduction between the emitter and the heat sink, it is highly recommended to apply a non-adhesive Thermal Grease to the back of the emitters to fill the microscopic gaps between the emitter and the heat sink.
This is by far the most labor-intensive method of emitter application as drilling and tapping the holes could be an hours-long process, and requires a certain amount of skill/technique to do correctly. One could also hire a machine shop to perform this task as well. Risks include but are not limited to: misaligned holes, broken taps, stripped threads from overtightened fasteners, and shorting of electrical connections to the heatsink. Benefits are the ability to swap out emitters in the event of a burnout, excellent heat conduction, no permanent goop, the ability to swap colors if you are displeased with the rendering, and the pleasure of hard labor.
This is one of the more convenient methods of application. Thermal adhesive typically comes in a 2-part epoxy that is applied in a small amount to the back of the emitter "stars", and it is then permanently affixed to the heat sink. Thermal Epoxy is formulated to provide a good amount of heat transfer between the emitter and the heat sink. The benefits include relatively fast application, good heat transfer, and permanent attachment when the epoxy sets. The risks include but are not limited to messy application and permanent attachment.
*Hoppy reports that with aluminum oxide based adhesive, he was able to pop off the stars using the blade of a knife and a little prying.
Thermal Self-adhesive Pads
This is essentially double-sided tape that is designed to conduct heat away from the emitter and into the heat sink. These are available pre-cut and ready to apply through several vendors, and are by far the simplest way to attach the emitters to the heat sink. Just peel the covers off, and stick it down. The reality is that as with any other application method, it takes a steady and sure hand to apply these consistently. It has been said that the heat conduction they provide is poor by comparison to other methods. The risks include semi-permanent application, poor heat conductivity, and higher price. The benefits include relatively fast and simple application, no mess.
Pre-drilled/Flexible Application Heatsinks
This is a relatively new class of heat sink that includes the MakersLED "designer" heat sink available through LEDGroupbuy.com and some other options available through other vendors. This particular model includes several "t" slot channels that receive bolts and nuts which when paired with the included insulating washers make applying the emitters relatively easy, flexible and semi-permanent. This virtually eliminates the drawbacks to the drill-and-tap method while maintaining the benefits. They are designed to receive most, if not all, brands of emitters. The benefits are the same as the drill and tap method, and the risks include a higher price.
Nope. Strictly a "for fun" type gadget.What do controllers do?
Controllers tell the driver what to do with the emitters. There are two kinds of controllers: manual and automated.What types of controllers are available?
A manual controller is a potentiometer that controls the dimming circuit of a dimmable driver. It regulates the current output to the driver, and controls emitter output that way. It is the least complicated and least expensive of the controllers available, as it only requires a 10v dimmable driver and a potentiometer wired to the correct circuit. For some drivers, the potentiometer will need to be independently powered - be sure of which kind you have before you attempt to make it work.
Automated controllers are electronic devices programmed to independently control the time, duration, and intensity of light from the emitters. They can be programmed to do an infinite number of effects and operations, some can be modified with relays and programmed to run other devices like CO2 and cooling fans. The limit is your imagination - and your coding skill. Or the number of friends you have who enjoy coding.
One could go with a pre-built controller, or a DIY controller, but there are many variations of each of these. The key to which particular controller you get starts with which type of driver you have: PWM or "x-10v". The difference between these dimming methods is the PWM is a digital method of modulation, and the "x-10v" method involves analog manipulation of the current.How do I program my controller?
PWMArduino (automated control)10v
Typhon (automated control) Available through BoostLED
O2Surplus' DIY Arduino controllerPotentiometer (manual control) available at any electronics store, and many emitter vendors.
DIM4 (pre-programmed automated control) available through LED Groupbuy.com
The answer to this will be different for each controller, but sink has provided us with a code he built for his Arduino controller to make smooth, linear dimming possible with particular drivers.
Series and parallel wiring are different ways to apply current to your emitters. Both can be used in assembling your fixture, but each has its individual purpose.What kind of wire should I use for my fixture?
This is the recommended way to connect your emitters so that they receive current. To achieve this, your emitters are wired to the power source by connecting the + of the first emitter to the power source, and the - to the + of the next emitter. The emitters are connected this way until the forward voltage limit is reached (see Driver section for more info on forward voltage), and the - for the last emitter is wired to the - end of the power source.
Here is a diagram showing series and parallel as well as an example of a bad idea.
It is important not to wire an emitter in reverse, as it is possible to destroy the emitter by applying current in the wrong direction.
It is not recommended to wire your emitters in parallel, unless you are putting together 2 strings of series-connected emitters to run from one driver. This splits the current between the two strings, running each at approximately half the current provided by the driver - provided the forward voltage limit for the driver is observed.
20-gauge wire is often used to connect each emitter, but heavier-duty wire is required to span long distances between the driver and the emitters. Please be sure to observe your local electrical codes when wiring your fixture!!! If you are uncertain about ANY aspect of this process, consult a professional electrician.How do I solder these emitters together?
For this, I recommend any of the many soldering tutorials available at the vendor websites, or taking a beginning electronics class in your area. This is a great skill to have, and most people can do this with a little knowledge and practice.Do I have to solder the connections?
For LED fixtures, it is frequently recommended to use about a 60/40 rosin-core solder to attach wires to the emitters, as this is pretty user-friendly. Rosin-core solder contains lead, so be sure to observe proper procedures when using it, and to keep it away from children or pets.
Different methods will require different soldering techniques. It is important to observe that duration of applied heat is your emitter's worst enemy when it comes to life span. It's wisest to use a higher-wattage iron (I have read 30W+ will do the job, but often read that 60W is recommended) as it is able to provide more constant heat, or a fancy soldering station with temperature control. Recommended temps to apply solder can be found on vendor websites like LED Groupbuy or Rapid LED's tutorial sections.
It is highly advisable to pre-tin your connections before you put everything together, as it reduces the amount of time heat is applied to your emitters. Pre-tinning is the process of applying a small amount of solder to the surfaces to be soldered together (the pads of the emitter star and the connecting wire). Do do this, there are as many techniques as there are individuals who do it. I simply melt a bead of solder with the iron tip, and transfer it to the surface to be tinned. Others heat the surface and melt the bead into it. Some use helping hands to assist, others tin after applying the emitters to the heat sink.
This last method requires the higher-wattage or temperature controlled irons, as the heat sink will do its job by conducting any heat applied away from the emitter, cooling the pads much more quickly. As we know, heat is our enemy, so with a low-wattage iron, you may need to apply heat much longer than is advisable.
Not necessarily. If you are terribly uncomfortable with wiring, there are options available to purchase clips from certain vendors that connect wires to particular brands and models of emitters. These eliminate the need to solder any connections. It is highly recommended to use solid-core wire with these connectors to ensure a solid connection. The major drawback is that they drive up the price of your build. Soldering is still the recommended method of connecting your emitters, and is a pretty easy skill to learn. Some vendors even provide tutorials on how to solder properly to avoid "cold solders," and other pitfalls of the process.
More info on the quality of these connectors would be helpful!