Power LED Light-Bar Ambient Lighting

Introduction: Power LED Light-Bar Ambient Lighting

About: I have a passion for tweaking things. Whether it be modding video game consoles, creating custom laser displays, or any creations with lights I love solving problems through unorthodox means. I like to go whe…

Create vibrant and colorful illumination for your home, man-cave, or living room.

This guide is meant to be practical, detailed, and highly accessible for helping beginners and experts alike create and install high-powered LED lighting. The design is simple -- attach high-power star LEDs to a thin strip of aluminum plate, and angle the emitted light down walls, illuminating the room in a spectacular fashion. 

This project is beginner friendly, great for a first timer working with small electronics. The cost is very reasonable if you are resourceful, and you can expand the scale to some pretty amazing installations. Once you have all of the parts, even a medium-size build can be done in one afternoon. There is plenty of room for expansion, namely using a micro-controller (e.g. Arduino) to control brightness for changing colors and patterns. This guide will focus on a simple on/off design for long-term, home use.

I hope you enjoy this instructable, gaining and sharing knowledge, and eventually creating a very cool and practical DIY lighting project.

Have fun building!


Step 1: Parts and Tools

This project can be as cheap or as expensive as you want it to be, depending on the scale of install you want to create. We will be focusing on a medium-install, which is two twelve-foot-length daisy chains, with two power supplies.

This is a long list, but nothing is outrageous or uncommon, you likely already have many of these tools. If you don't have a tool, ask around, there are many sad, lonely tools sitting on unused workbenches.

Most small electronics should be bought on eBay. Distributors from China sell directly to the public through it. It is not uncommon to see $7 per 3W LED in a physical store in America, rather than $0.50 bulk on eBay. Expect to wait a week or two for parts though.

  • Aluminum Plate [Variable Price]
    • The base structure that the LEDs will be bonded to, it dissipates heat very well. I purchased a 4' x 2' plate of 1/4" aluminum at my local scrapyard for $12 which I cut into strips with a Jigsaw, 4' x 3" each. The scrapyard will save you absurd amounts of money for a little effort. Buying new can easily cost $100 in metal.
    • Recommend 1/4 - 3/8" thickness. Though 1/8" will work, you need to be careful to not let it bend too much since the LEDs are bonded to it.
  • 3-Watt LEDs [3x ten-packs of Red, Green, Blue, $12 each]
    • Often called Luxeons or Star-LEDs, they are high-powered LEDs that require being mounted to a metal plate for heat removal. Their usable life is nine-years of non-stop use.
    • Always shop around different sellers on eBay for each color, prices can vary a ton. One store sells 10pcs Blue for $20, another for $10, exact same LEDs (Lumen value, 100Lm is plenty).
    • Search on eBay in the format: "high power led 3w COLOR 10pcs". Bulk is cheaper.
  • Resistors [2x 5-packs for $3 each]
    • On the page, "Resistor Math" we will discuss finding the right kind of resistors. I purchased two five-packs for 3.3 Ohm 5 Watt. Your numbers will likely be different depending on the LEDs you buy. 
    • They are measured in resistance (Ohms), and how much heat they can remove (Wattage).
    • Search on eBay in the format: "3.3 Ohm 5W".
    • There is a big difference between 3.3 Ohm, and 3.3K Ohm (3,300). Make sure there is no M or K in the name.
  • 12v, 4Amp, Power Supply [2x for $9 each]
    • Generic Laptop and LCD-screen power supplies provide DC electricity, at high current, regulated power, for very good prices. Also purchased on eBay.
    • Search on eBay in the format: "12v 4A power supply".
  • Artic Alumina Ceramic Thermal Epoxy [2x packs for $10 each]
    • Very strong glue, that is able to conduct heat, but not conduct electricity. If it did conduct electricity, like in silver-based epoxies, the LEDs can short each other out. 
  • Wire
    • I recommend using 20-22 AWG (Gauge/thickness) wire, since we are dealing with fairly high power loads for small electronics (~25 watts over the length of the daisy chained LEDs).
  • 9v Snap-On Connectors [12 Snap-Ons needed, $5 per 5-pack bag at Radioshack]
    • These are used as power-connectors, and to daisy-chain the light-bars together.
  • 1" Ell Brackets [12x needed]
    • Used to mount the plates to the wall. Use 120 degree ells if you can find them, otherwise bend the 90 degree ells with pliers.
  • 1/4" Diameter, 3/4" Length Bolts w/ Nuts [12x needed, $5 for a box of 25]
  • Nails or Screws [$Peanuts]
    • For mounting the Ells to the wall.

Tools - Electrical
  • 15W Soldering Iron [From Radioshack, $15]
    • Heats up to 450C, melts solder, which conducts electricity and bonds wires together.
  • 0.022" Silver Rosin-Core Solder [From Radioshack $4]
    • Makes the mechanical/electrical bonds between connections.
  • Wire Stripper [From Radioshack $15] (Optional -- You can always use a knife or X-Acto Knife)
    • Massive time-saver, cuts and removes sheathing from wires. Strongly recommended.
  • Needle-Nose Pliers
    • Used to hold wires while they are soldered to LEDs and connectors.
  • Heat-Shrink or Electrical Tape
    • Heat shrink is a rubber tube, that when heated, tightens and seals components. Much cleaner and stronger than electrical tape. Same job though, covers exposed connections and prevents short-circuits.
  • Multimeter [From Radioshack $10] (Optional -- You can just quickly tap connections and see if lights turn on, risky though, could fry the LEDs).
    • Useful for measuring voltage levels (not too much or too little electricity), and measuring polarity (which wire is positive or negative).

Tools - Mechanical
  • Jigsaw [$50 from Lowes, if you don't own one, ask around, someone you know has one that is sitting unused]
    • The correct tool for this job is a plasma-cutter, but those cost a great deal of money.
    • Used to cut the aluminum plate into strips.
    • Requires blades, get 14-21 TPI (Teeth Per Inch), for thick metal.
  • Aluminum Cutting Fluid [$3 from Lowes] [Just take your time to prevent warping from overheating the aluminum)
    • Makes cutting much faster and easier. Less vibration, blades last longer.
  • Power-Drill [$50 from Lowes, again, you already have one or know someone who does]
    • We only need to drill a few holes for bolts to combine the bar and bracket, a single 3/8" drill bit is all we need.
  • Acetone [$8 from Lowes] (Optional -- Just scrub with soap and water if you're that broke, wear gloves, cut aluminum is sharp)
    • Used to clean any sharpie marks on the aluminum, clean the metal, and wash away any cutting fluid.
  • Angle-Grinder [$70 from Lowes] (Options - Very optional, I use it to make the aluminum have a pretty brushed swirl pattern with a wire brush, along with smooth down sharp edges)
  • Leather-Gloves
    • The aluminum will become very HOT when cutting. Also prevents slices from sharp-edges.
  • Earplugs/Hearing-Protection [$10 for a tub of 100]
    • Cutting aluminum with a saw can be extremely loud, your ability to hear music will thank you.
  • Bar Clamps [$15-20 each, 3 or 4x. Again, ask friends if you are short.]
  • Rags [$5 for 5 rags]
    • Pour acetone on these and clean away marks.
  • Hot-Glue Gun and Glue-Sticks [$20-30]
    • Holds the soldered wires to the plates, you'll be using a lot of glue. I suggest a blue or heavy-duty gun for more heat.

Step 2: Resistor Math (Necessary)

Not all LEDs are made the same, different manufacturers, different voltage and current levels.

There are three parts in measuring the power of a LED: Forward Voltage, Amperage (Current), and Wattage.

Volts -- How hard electricity goes into the LED.
Amperage -- The volume of electrons consumed by the LED.
Wattage -- The total amount of power the LED uses, wattage is a unit for comparing energy usage.

Watts = Volts * Amps.

Wherever your purchase your LEDs from, they will always give you two pieces of information, the Forward Voltage Drop, and the amperage.
Here are some very common number ranges:
  • 3W White, Blue, Green: 3.2-3.6v, 650-800mA.
  • 3W Red: 2.4v-3.2v, 650-800mA.
  • 5mm White, Blue, Green, Ultraviolet: 3.0-3.4v, 20mA.
  • 5mm Red, Orange, Yellow, Pink: 1.9-2.4, 20mA.
Calculating for the Right Resistors
Head over to LEDCalc.com, this is a tool that tells you what resistors to get for your LEDs, depending on what kind they are and how you wire them.

There are three common kinds of wiring circuits:
  • Single - One LED, one resistor. We won't be using this because it is less efficient, expensive, and time-consuming.
  • Series - Multiple LEDs, one resistor per chain. The LEDs are connected in a chain end-to-end, but the chain can't go on for more than four or five LEDs. This is what we will be using.
  • Parallel - Unlimited LEDs, one shared resistor. Wiring is super easy, all LEDs use the same positive and negative wire. Only practical for low-power circuits, all LEDs share one massive resistor. We won't be using this.
Enter your Forward Voltage Drop, amperage consumption, and number of LEDs in the series chain. LEDCalc will provide you a recommended resistor to use.

The closer you get to total voltage drop comes to equaling source voltage, the smaller the resistor necessary. So a 12v line, can support four LEDs running at 2.9v with a small resistor. There is simply less spare voltage to resist.

The Numbers Used in This Design
These numbers were selected specifically because it makes wiring easier, along with outputting moderately low heat.
Four Red, 2.4v, 750mA in series: 3.3 Ohm, 2W required.
Three Green/Blue 3.2v, 750mA in series: 3.3 Ohm, 2W required.

Undervolting and Overvolting (Dimmer and Brighter)
Adding or removing LEDs changes the resistor you can use. You can also reduce the power of the LEDs by undervolting them, providing 2.8v when they need 3.2v. Or you can make them brighter by overvolting, providing 3.6v when the LED needs 3.2v. This lengthens or lowers the life of the LED significantly (A overvolt from 3.2v to 4.0v can drop the usable life from nine years to three years... still a VERY long time of use).

Rating of Resistors
Resistors are rated in two ways, resistance/impedance (Ohms), and heat dissipation (Wattage). There is no harm in using a resistor with a higher wattage rating, it simply means the resistor will be physically larger (dissipating more heat). I always go a level higher, if I need a 3W resistor, I use a 5W. It's nice to have resistors that don't give you burns for only $0.10 more.

Step 3: Design Choices and Power Supply Math (Optional Learning)

It is likely the design that best fits your build, will not match mine. Different sized rooms, different budgets, etc.
It is also very important to note, that not all LEDs are the same. You MUST know the numbers of the voltage and current your LEDs run at for the resistors to work.

Here is the reasoning behind the numbers I picked for Resistors, Power Supplies.
Math lessons can be really stupid and frustrating sometimes, so I try really hard to make my math sane and useful.

Color and Brightness
All three colors were desired for day-time brightness lighting, Red, Green, and Blue. Having all three makes everything in the room visible (white is the interpretation of RGB), so you don't get diseased looking pizza like when under blue-only light.

Really Bright: 120Lm+, you don't want to look at it directly.
Medium brightness: 60-90Lm
Dim: 40-60Lm, it's still dark, but at least you don't stub your toe.

If you want night-time lighting only, that people could still sleep under, go low-lumen Green (40Lm) and low-lumen Blue (60Lm). I'm using a range of 70Lm Green, 70Lm Red, and 90Lm Blue. Human eyes are most sensitive to green and least sensitive to blue.

Power Capacity Calculations -- Which Power Supply to Get
When comparing power capacities between systems, always use Watts. Wattage is simply Volts * Amps.
If you have a 12 volt, 4 Amp power supply, it's a 12v * 4A = 48 Watt power supply. Always run your power supplies with an extra 15% of capacity, they aren't meant to run at their limit 24/7 or they get extremely hot and die after awhile.

Despite their name, most 3W LEDs don't actually consume three watts of power. It's just, more than a 1W... These are the numbers for my LEDs, yours will very likely be different.

3x Series, 3W Green and Blue LEDs: 3.2v Voltage Drop, 0.75A Current.
4x Series, 3W Red LEDs: 2.4v Voltage Drop, 0.75A Current 

Chain One:

21.6 Watts
Blue: 3 LEDs * 3.2v * 0.75A = 7.2W
Red: 8 LEDS * 2.4v * 0.75A = 14.4W

Chain Two:

21.6 Watts
Green & Blue: 9 LEDS * 3.2v * 0.75A = 21.6W

If you want a single supply:
12v supply, Theoretical 43.2W, + 15% needed.
15% of 43.2= 6.5W
Realistic wattage needed: 49W, 12v supply.
49W / 12v = 4.1 Amps.
So a 12v, 4.1 Amp+ supply is ideal. The 4.0 Amp ones would work fine, just, they'll be fairly warm.

If you want two separate supplies, one for each chain:
12v, Theoretical 21.6W + 15% needed.
15% of 21.6W = 3.2W.
Realistic wattage needed: 24.8W, 12v supply.
24.8W / 12v = 2.06 Amps.
So a 12v, 2.06+ Amp Supply per chain.

Step 4: Aluminum Measurements and Cutting

There are a total of six, four-foot long, three-inch wide light-bars. There are two light-bars of each color, red, green, and blue. Red bars are running in series of four, green and blue bars are running in series of three.

*Important Notes*
Before cutting, put on protective glasses of some kind. Sawdust can wash out of your eye and is semi-pulpy, metal-dust has to be picked out of your eye and is very sharp. Keep your head away from the Jigsaw when cutting, just reducing the amount of flakes that can hit you.

If your aluminum heats up to the point you don't want to touch it with your bare skin, just stop and wait a few minutes for it to cool off. You can always throw a cup of water on it to cool off more quickly. Too much heat causes curling and warping of metal. If the Jigsaw begins knocking or vibrating heavily, change the blade - they can wear out really fast.

  1. Clean the aluminum with water and a towel, both sides.
  2. Do a second clean/scrub with acetone if you have it on the room-facing side.
  3. Mark your cutting lines with a sharpie on the aluminum using a level or ruler.
  4. Mount the aluminum plate to a cutting surface like cinder-blocks or saw-horses, using C-Clamps or Bar-Clamps.
  5. Apply aluminum cutting fluid directly over the sharpie line.
  6. Cut the aluminum very slowly with your jigsaw blade, let the blade pull you, don't push it to go faster.
  7. After the cut, remove the aluminum, cut the next bar.
  8. Once all bars are cut, wash up the aluminum with acetone (if you have it), or rubbing/isopropyl alcohol, which can also dissolve sharpie.
  9. Optional - Grind down the edges of the aluminum bars with an angle-grinder or coarse (100 grit) sandpaper.
  10. Optional - Angle grind in a pretty swirl-pattern into the plate with a wire-brush attachment.

Step 5: Wiring Design and Preparation

Wiring Layout
There are three wire paths, a power and ground, which run down the lengths of the light-bar on opposite sides, and an active path that carries electricity from power, to the LEDs, and out the ground. At the end of each light bar are 9v snap connectors solder to the power and ground lines. These provide end-to-end connections for daisy-chaining. They are wired oppositely on each side since polarity flips at each connection (second picture). The power-LEDs are connected in series, meaning, Positive -> Negative -> Positive -> .,. The pictures help make this clear.

Measuring Positions for LEDs
The LEDs should be spaced evenly across the light-bar. This is done by taking the total length, and dividing it by the number of LEDs plus one. So a 48" plate with three LEDs, would be:

48" / 4 = 12".

Thus, the three LEDs should be placed at 12" increments, starting from 0. This means marking the LEDs at 12", 24", and 36".
The LEDs should also be marked with a Positive and Negative symbol on each side, it's important to keep them facing the same direction.

Prepping the LEDs for Mounting
Use low-grit sandpaper to scrape the location of the LED. Then wipe it with a rag and fluid (water or acetone) to clear any flakes. Scraping the plate cleans the area, and gouges the metal so the epoxy has more surface area to bond to. Scrape in circles, and then horizontal/vertical.

Step 6: Epoxying LEDs, Soldering Resistors

With the Artic-Alumina Ceramic Thermal Epoxy, we will mix equal batches of part A and B on a platter (CD-tray). The epoxy dries very quickly, in under five-minutes, so I recommend only doing two or three LEDs at once.

Ensure that your LED polarity markers ( + and - ) are facing the correct direction when you bond them. Once they're bonded, nothing is taking them off except for a chizel.

Pour two pea-sized globs of part A and B onto your platter, and mix them thoroughly. When they make a mixed rough-paste, apply in a thin circle where the LED will be placed. Then place the LED onto the epoxy and move it around in small circles until the entire surface-area of the LED is bonded.

Wire, Resistors, and Heat-Shrink
Measure out and cut the length of power-wire for the length of the bar, usually 50" for a 48" bar. Using wire-strippers or an Xacto knife, cut the sheathing of the power wire and expose some of the metal. Wrap one of the resistor legs around the exposed wire, and bond them with solder.

Cut off a piece of heat-shrink, and slide it along the length of the power-wire until it covers the wire/resistor bond. Then use the lighter to tighten the heat-shrink.

For the remaining leg of the resistor, bend it into a U-Bend shape with needle-nose pliers. Pictured below.

Step 7: LED Terminals, Connecting Resistors

Tin the Terminals
It is far easier and quicker to bond two pre-tinned objects together, so we will apply solder to both the resistor and first LED positive-terminal to connect them.

These high-power LEDs are fragile, NEVER hold the iron to a LED terminal for more than two-three seconds or you risk frying it from internal heat-cracking. 

To tin a LED terminal, place the solder flat, directly on top of the terminal. Then apply your soldering-iron on top of the solder/terminal and wiggle it around a little. Feed in solder, until there is a shiny-bubble of solder

Clip the U-Bend leg of the resistor to a length short enough that it will never bump into the plate. Now touch the U-Bend leg of the resistor and positive terminal of the first LED together (pictured), and bond them with the iron.

Step 8: Connecting the LED Chain

Now that the first LED has been connected to its resistor and power wire, we can connect the rest of the LEDs in the chain. It's a fairly simple affair, positive -> negative -> positive, until we end in a negative that continues into the ground wire.

Using the thermal ceramic epoxy, bond the rest of your LEDs to the aluminum plate. Connect the respective positives and negatives together by pre-tinning the wire and terminals, and bonding them together.

On a star-LED, the positive terminals are connected to each other, just as the negatives are. This is simply to make wiring easier.

Measure out and cut the next wire in the chain, leave a little room to allow the ends to touch the terminals. Shorter is better, though do not cut it so short that there is strain/pulling on the terminals. Then tin and bond the terminals.

Place a large bead of hot-glue onto the aluminum plate at a stress-point for the wires. Then set your wires onto the glue. Pictured below.

Once all your LEDs are connected in their chain, solder the main ground line to one of the ends of your 9v snap-on connector.

Step 9: 9 Volt Snap-On Connectors & Power-Supply

It's time to terminate the ends of the light-bars, so they can be daisy chained to one another. I like to use 9v snap-on connectors because they are cheap, plentiful, don't come apart easily, and can take a decent amount of current.

On the down-side, every time you make a connection, the polarity reverses (Pictured below).

The way to get around this, is just make sure the start, and end, of each light bar are opposite to each other and in the same order.

Preparing the Power Supply
Inside your DC power-supply, there are two wires: positive and negative. Positive is usually red, brown, or white. Negative is usually black or blue. Use a multi-meter to check if you are unsure.

Grab some scissors, cut off the end, and strip the wires at staggered lengths so they can never bump into each other and cause a short.

Connecting the 9V Snap-On Connectors
Grab your 9V Snap-On Connector, and determine which polarity you want. Apply a small piece of heat-shrink, maybe one inch or so, and apply it to the 9v Snap-On. Then cut the 9V Snap-On wires to the proper length, maybe two inches.

Pre-tin, and solder your wires together, test if they light up correctly, then heat-shrink. If they don't light up, then either your chain is not a closed circuit, you have a short somewhere (where metal is bumping into the plate), or your polarity is backwards.

Keep working to finish the ends of each light-bar, and test the daisy chain junction points.

Step 10: Wall-Mounting

We're finally here! The light-bars are fully functional, we just need a place to hang them.

Bending Ell-Brackets
Grab a vice and a large pair of pliers, and begin bending your Ells to about a 120 degree angle. If you don't have a vice, use two pairs of pliers and bend them in opposite directions.

Drilling Holes in Plates
Only two Ell-Brackets are needed per light-bar. We will use the same math as before. For a 48" bar, divide by the number of Ells plus one. So, 48" / 3 = 16" increments. So we will drill holes through the light bars at 16" and 32". 

Then place a leg of the Ell underneath the light-bar plate, and bolt it in. We only use one bolt on the Ell, to provide room for inaccuracies in drilling holes in the wall.

Mounting to Wall
Drill a hole in the wall. Since we use 16" spacing, and studs in most American homes are 16" apart, we used a stud-detector (knock-knock, human knuckles) to find and drill into studs. If you don't have this spacing, you can use drywall screws, we are not holding up much weight, maybe four pounds at most.

Great job, you're finished, and can now enjoy some fantastic nights of illumination!


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    Lee Wilkerson
    Lee Wilkerson

    6 years ago

    Excellent work! Great 'able! Bravo!

    I would have used some other less confusing technique for connections. For example: co-axial power connector. Male on one end/female on the other.


    8 years ago on Introduction

    Hey, I really love this instructable, and wanna do it myself, but I want to ask something before I start.

    My bedroom is a large room, weirdly split by a girder, thath being my man-cave, it's actually less than 1/4 of the total room space, I wanna paint it's three walls in black and give them some color with LEDs. Do you think it will work out? And th eother question. Should I get 3mm or 5mm LEDs.

    I found those ones, and I guess two packs would be perfect. But I don't really know the best dimensions for them. Thanks for your idea.



    Zen Innovations

    Liked it.
    How "White" Glow can you get by keeping all the colours on?

    And oh yes! It would be tons better to use an LED Constant current source rather than Resistors. Resistors generate heat and waste energy as well.
    I purchased a 10 LED 350mA driver for just Rs 500 From Bombay. You should have better prices online.
    Good luck for the Contest!


    10 years ago on Introduction

    VERY well written instructable! You should enter the Make it Glow contest.


    Reply 10 years ago on Introduction

    Thanks for the comment, they are always appreciated and are motivation to write more guides, even if the projects never stop =D

    I have entered it into the Make it Glow contest, it is pending approval. If you can think of any ways I can make it better, please let me know.

    These light bars are actually the earlier form of this design, it has since evolved into the attached picture. Might make for another fun guide.