DIY LED FAQ - Where to begin?
1. To begin, let me first state that I am not an expert.
I, like a good little parasite, have taken copious notes to keep track of all the info needed to build one of these things. The info was sourced from other hobbyists, vendor websites, and other DIY oriented information sources. After collecting these notes, it was suggested that a thread might be in order to share all of this info in one place.
I built this guide as a reference page for those like me who need to learn as much as they can about LEDs prior to undertaking a DIY build. There will be many mistakes in this first draft, but I have done my best to make this as clear and accurate as possible.
This is kind of like a Choose-Your-Own-Adventure book. It’s set up as a Q&A discussion with links to relevant sections. Start by considering your most important aspect of this project. I have provided a link to what I think is the most helpful info related to that aspect. I have attempted to provide as much info as I have learned in one location. Given the vast amount of information on this subject, I will be glad to add external links and expand, correct, or otherwise increase the utility of this info guide.
Again, I am not an expert. Consider me more of an archivist with some nominal practical experience (and thus a total nerd). I have compiled as much info as I can from those who are. I haven’t cited specific sources of info in this thread as it is not a scholarly paper, but just a humble FAQ.
A few shout-outs to the pioneers of this process who made mistakes so the rest of us don’t have to. They may not consider themselves experts, but their experiences and experiments have made some great contributions to our hobby.
(I'll add others as I remember them, as I know there are more!)
I will not accept responsibility for any projects, builds, experiments, plans, or explorations created by anyone using the information contained herein. This is YOUR build. The author claims no responsibility for any damage, injury, fire, explosion, alien invasion, supernatural habitation, spousal rage, second coming, paper cutting, molten formica, ruined pants, or other unfortunate circumstance resulting from the creation of a device using information from this guide. This resource is intended as research utility only!
That said: have fun!
Table of Contents
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!
3. Where do I begin?
What’s most important to you?
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!
What am I looking for?
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.
Important specs to know about your Emitters (in no particular order)How many for my tank?
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?
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.
6. Emitter Layout
How far apart should I space them?
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?
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.
What is the difference between optics and reflectors?
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?
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.
How do I choose one?
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.
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?
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?
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.
What is a heatsink?
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?
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.
Do I need a controller?
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?
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?
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.
11. Emitter Wiring
I debated even putting in this section, as there is such an abundance of info on this subject that there are degrees and licensing processes in place to assure that the professionals understand what they are doing. Essentially, if you don't have at least a working knowledge of electrical wiring before you create your fixture, you have no business building one. I have to admit that I still have a fair amount to learn, myself. What I will provide is a few basic comments as it pertains to LED fixture construction. This includes just enough info to get you started, and is by no means considered complete.
*Please let me know IMMEDIATELY if any aspect of this section is incorrect.
Electrical wiring is dangerous. Build at your own risk. If you do not understand what you are doing, you risk injury to yourself or others and property damage or destruction by fire. It is highly recommended that you consult a licensed electrician before you commit to any aspect of your build. The author is not responsible for any injury, death, accident, fire, damage or destruction to personal or real property as a result of creation of a device using this information. This guide is intended as a research reference only.
What is the difference between Series and Parallel wiring?
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?
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?
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.
Other Helpful Links
12. Other helpful links
Thanks to jcgd for helping me gather these in one spot!
*What other sites have you found that provide great info for us? Let me know!
Ok, that's it for the sections I have so far. I will diligently update and format this as soon as I am able. I will, meanwhile, gather more info on the subjects that need addressed. In the meantime, post your builds, successes, mistakes, complete failures and any other info that you might think would be helpful! Remember forum rules - no vendor reviews! But information is always helpful :)
nice write up. I found this http://reefledlights.com/how-to-diy-led/ for some good tips when DIY. alot of good stuff even though it intended for reefs
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