Step 5: Power

Power Supply
Your power supply can be from pretty much anything. An old PSU from a computer, a leftover hard drive power brick; I prefer small and compact power supplies such as those in cordless phones. Laptop power supplies are an amazing power source, they are super cheap and available, usually can supply 3-5 amps (which means a max of about 230 LEDs), and are regulated [which are normally super expensive] at 12v DC. No matter what the plug on the end is, you can bet there are two wires in there: Positive and Negative.

I obtained three 9 volt power supplies at my local goodwill for $3. eBay also has a plentiful selection of power supplies, though it will take some searching. The supply needs 350mA or more to power 18 LEDs. mA determines the maximum amount of LEDs. 99% of 5mm LEDs use 20mA each, so just multiply the number of LEDs by 0.020A (18 LEDs * 0.020A = 360mA, which is technically overloading it, but it still works). 

The speaker wire will carry the electricity from the power supply wires to the LED wires. Decide right now which of your two speaker wires will be your positive, and which will be your negative.

As a general rule, the red, yellow, white, or lined wire is the positive, while the solid (usually black) is negative. After the next step, you will have two LEDs and a resistor soldered together. Just try touching them both to the speaker wire, whichever lights up for you is your correct solution.

Quick Disconnects
This step is optional. It makes it easy to plug and unplug the light bar from the power supply. If you don't want to use Quick Disconnects and want the power supply always attached, just twist the wires of the speaker wire and the power supply together and solder them. Wrap them with electrical tape to keep anything from shorting out.

Quick Disconnects have a wire going into them, and usually you just crush it with pliers (Called crimping) and the wire stays in place. An optional purchase to skip this awl & solder method is a pair of crimping pliers. Regular pliers were incapable of doing the job for me, so I pierced and soldered them into place. Knowing from experience now, I strongly recommend just buying crimping pliers than this next awl + solder method. If you don't feel like spending money, then go for this method, which actually is a stronger connection than crimping alone.

Because its not possible to stick solder into the Quick Disconnect (its covered in plastic) and melt it and the wire together, you should coat the end of your wire with solder. Stick the wire into the quick disconnect. Now hit the Awl on top of the Quick Disconnect, this will pierce the casing and squish the metal and wire together. Follow it up with sticking the tip of your soldering iron into the hole to melt the solder. You should have a very solid connection between the wire and Quick Disconnect. Finally, wrap any exposed areas up with electrical tape.
Is there a way to use many different colors and have some type of switch to turn each color on and off separately to create different combinations?
I should also add on, that this guide is rather old. Recently there are now LED ribbons that do the exact same job (R-G-B-R-G-B) as my painstakingly made light-bars. A TON easier and cheaper, eBay is your best source. It's going to be a number and a RGB ribbon, I think the 5050s SMD/SMTs were the best model I found. Hope that helps!
Indeed, it requires a micro-controller using pulse-width-modulation. It doesn't have to be as hard as it sounds.<br> <br> I previously was working on an Instructable for this exact project, but I got tired and never finished writing it for publication. There is enough in there to figure it out with some work, and it's a good start.<br> <br> It is located here:&nbsp;<a href="http://www.instructables.com/id/ESTRWXVFYTCLJ5J/" rel="nofollow">http://www.instructables.com/id/ESTRWXVFYTCLJ5J/</a>
Okay so I have a quick question. How would you add a female and male audio jacks to this circuit so I can play music along with making the lights flash? Currently I have 100 LEDs and a 12V wall plug that has 1amp work of power since thats what I need to run the lights. Pleasepleaseplease help me.
Correction 50 LEDs
Definitely much harder. I have been working on it myself and to do it through a micro controller you need programming experience. And through analog you need schematic experience. <br>
It's actually much, much harder than you would think it is. You'll need to have a programmed microcontroller (Arduino is the most common for this), which can either a) react to a microphone and turn on/off power related to volume or frequency, or b) program the microcontroller to listen in on the raw audio-feed from your computer with a serial connection. It's a pain and it's expensive since you need equipment for programming and operating the chips. Wish I had better news =[
I am not much into electronics but while going through the comments of your instructable u said that one can't connect more than 2 leds in series , then how do christmas chain leds work with a consistent glow though they are connected in series.. ? i hope u get me .. <br>
They are actually run in parallel.
Hey..vthanks for the Ible just wanted to ask a few quick questions.. This Ible inspired be to go out and do my first led project but mine is going to be made out of half of a PVC pipe.. Okay so if I run in parrellel of I do instead of 3 bulbs per resistor it's fine to do just 1 per resistor right? And also does parrellel really drain batteries as much as everyone makes them out to be or is it slightly more than series or what? Any help is appreciated.. Thanks for the insfructable once again I'll be posting my project when I get it done and I'll probably mention you in it for inspiring me but anyone please get back to me... Thanks! <br>
Parallel uses more juice, because more stress is placed on the resistor, which is emitted in the form of heat. There are three primary resistor wirings: single [One resistor, one LED]; series[one resistor, multiple LEDs in a chain]; and parallel [one resistor, unlimited with common positive and common negative]. Yes, parallel does drain batteries more. Wiring single-per-LED is the most efficient actually. The maximum you can realistically hit with parallel, is about 7-10 LEDs per resistor before the size of the resistor becomes ridiculous. There is a danger in parallel though, if one or more of the LEDs fails, then the power output to the other LEDs increases.<br> <br> Also, funny you mention this guide, I am writing the sequel to this at this very moment. The guide should be completed in about a week, and I must say, it is turning out pretty dang awesome.<br> <br> If you have any other questions, feel free to ask.
I never heard about that. Is that only if you have like 2-3 less per resistor? Or is that with one led per resistor too? Or what.. I kinda confused now.. ( I'm 13) lol also message me the Lin to the sequel when you get done too if you think bout it.. I'd love to see it.. ;) thanks!
The entire build and install was completed today. Aside from gathering parts which took about two weeks of course (shipping from China is slow). Took about 200 pictures. I need to clean up the house and make everything pretty for photos in the guide though, but here is an idea of the result.
That's pretty sweet man.. Are those neon tubes or is it just tightly packed LEDs? <br>
Also can you answer the question.. Because if that's a danger I'm gonna be bowing up my LEDs.. Lol.. <br>
&quot;that&quot; is the danger you mentioned about.. Sorry bout any confusion..
hey this is a really cool. i am 14, do you think this project is suitable for me to make and do you think you could even put your idea into a water feature??
I'm 12. And im making this. Everything is ok, just i dont like the soldering :D
I'm 13.. And making this :) we should all team up us teens and make something AMAZING! Lol.. I'm making my own twist on this bar.. Be posting a Ible soon on it if you want help..
Hehe, I'm all excited now, it brings me great joy to see others building and learning and developing their skills. Be sure to link me to whatever you make. I've got sequel to this instructable, a few years of evolution in the making, that will be released within two weeks.
Do not let your age hold you back, by the expectations of others or yourself, if you are interested in a project pursue it to the best of your ability. If it doesn't turn out well, you will always learn something from failure. There have been electronics pioneers far more skilled than me before they were even 14 (I'm 21 by the way).<br /> <br /> As far as combining the light bars with water, unless there is something moving within the water, it will just look like a light is passing through your body of liquid, no different than a light-bulb or fluorescent tube. Electronics don't work well with water, and making a submersible light bar water-tight would be a lesson in failure.<br /> <br /> There are however applications that involve LEDs and water. One of my favorites is rapidly pulsing LEDs that shine indirectly (meaning you don't see the LEDs themselves) into falling water droplets. The LEDs of red, green, and blue change color very rapidly, on par of 20-30 different colors a second. Depending on a water droplet, if it falls into the path of a LED as it is a certain color, it looks as though you are seeing falling jewels. Bigclives.com RGB microcontroller kit has&nbsp; pre-programmed patterns, including one for water droplets. That's a rather advanced project for a complete beginner (more advanced on the water droplets than the lighting), but if you are interested I use his controller for lighting my apartment. Here is a link to my instructable which is currently unpublished. <a href="http://www.instructables.com/id/ESTRWXVFYTCLJ5J/" rel="nofollow">http://www.instructables.com/id/ESTRWXVFYTCLJ5J/<br /> </a><br /> You would need to be a bit more specific by &quot;water feature&quot;, there are a million different ways to interpret a water LED project, whatever you decide to create, make an instructable and send me a link when you are done.<br /> <br /> Lastly, this instructable I consider to be a great beginners project, it's one of the first things I ever made electronically, explains the basics of LEDs, resistors, amperage, and voltage, and doesn't need to be precisely done. I say, go for it!<br />
This is a cool instructable, thank you for posting it. <br><br>I have a similar question about water. I was thinking about making this to put outside behind a small glass block wall so at night the LEDs will light up the wall, but I'm afraid it will not last long once it rains. Any advice? I was thinking maybe using hot glue around the LEDs and any openings to try and make it water tight. <br><br>Also, I'm very new to electrical work, with a 9V power supply and the LEDs only needing 3ish would I be able to double the size of this and make a 10 foot bar? <br><br>Thanks.
When comparing the power ratings of your LEDs and your power supply, use watts, not volts or amps. Watts = volts * amps.<br> <br> If your 9v power supply pumps out 340mA, it would be able to supply 9v * 0.34A = 3.06 Watts.<br> <br> Even though the LEDs run at 3.0v, it's easier when doing a chain of them to have the supply have a higher voltage. If you want a ten foot bar, calculate how many LEDs it would be, then add up the Watts. I imagine that would be something like 40-50 LEDs for ten feet. 5mm and 10mm LEDs run at 20mA. so 0.02A * 3.0v * 40LEDs = 2.4 Watts. Pick whatever number you want, whether it be 50 or 100 LEDs, just calculate by the watts.<br> <br> Don't try waterproofing the light-bar, you will be let down and become frustrated, especially at the electrical connector (though you could just stick the wire directly in and hot glue it). By this I mean, do not try to waterproof your light bar to the point you can submerge it in water. If you're just adding extra hot glue to keep out moisture, it's better than nothing I suppose.<br> <br> I've seen an installation where someone used LEDs to light up their glass block wall. First off, he didn't use dinky dim 14kmcd 5mm LEDs, but 10mm 70kmcd LEDs (kilo millicandela, a measure of brightness), and around 40 of them (three per block). The lights were placed on top of the glass wall facing downward. He had to make little risers to keep the LEDs from bumping into the glass so they could face straight down.<br> <br> Though his installation was inside of a wall for a bathroom, it sounds like yours is standing outside in your back yard. To protect it from the rain, get a small piece of flexible waterproof plastic (heck, I bet scissors and a cheapy rainjacket would do), and just throw it over the light bar so the rain doesn't land on it. It shouldn't need to be very wide, just enough to cover the light-bar and touch whatever surface it is sitting on. I made a quick picture to show you what I mean. If you have any more questions, feel free to ask.<br>
Thanks for the quick and detailed response. Yes, the block wall is outside, and I see your diagram of having it on top of the blocks, but the blocks I am using are rounded at the top and rounded on the corners; additionally, they are held together using mortar. If I were to place the LEDs on the top, only the top row would be lit as the light would not penetrate the mortar to light the blocks below. <br><br>So, what I was thinking was placing it behind the wall and allowing it to shine up along the back of the wall, similar to what you did with the lights behind the couch. With the blocks being clear and diffused it should light the blocks up as a fade from the bottom to the top, the bottom blocks being the brightest. The issue with this is that the lights sine directly up, and thus could not be covered. Maybe if I fill the track with silicone after all the wiring is done to ensure no water can touch the wires that might elevate much risk. I don't know. I am thinking of making one just for the hell of it and seeing how long it lasts. <br><br>Thanks again for the response
How would you go about making a rippling effect? <br>You know, random dimming if selected LEDs? Thx.
would i be able to use your light bar for the light sorce for this instructable. <br>http://www.instructables.com/id/Music-LED-Light-Box/. <br>and would any modifications be nessasary?
You could make the light bar music reactive yes, they are a very similar design. The only difference is that you would need multiple TIP31 transistors, one per four LEDs. You can't run 18 LEDs in series, they wille be either extremely dim or not light up at all. Both projects have very similar wiring, just replace the + and - terminals of the battery with the + and - wires of the power supply. Though he is using 12v, I believe you coud use anywhere from 6-12v for the project, just make sure your supply can handle the 18 LEDs. Though I normally say to always use a resistor, I believe you do fine without them by using the transistor method.
Is it really necessary for a transistor on each of the strings of LED's? Is it possible to just do something like this (see attached pic). I assume it would be ok, providing the total power rating of the LED's doesn't exceed the power rating of the transistor.. But I could be missing something?<br><br>Thanks :)<br>Denno
Sorry, doesn't look like the pic uploaded correctly the first time. here it is now, hopefully this one works..
That circuit looks like it would work just fine. Note that I did not say to connect a transistor to each LED series, but rather a resistor (wavy line) to each LED series, just like in your image. And yes, you need to make sure the transistor can handle the power rating of all the LEDs it will be connected to. That shouldn't be much of an issue, as LEDs are low-power. You will likely need a small heatsink for the transistor.<br><br>Thank you for your input.
did u mean dat 2500 mAH is capacity of each battery?<br>if so then totally it will be 5000 mah but just as the capacity is lessened,it shud still remain 2500 mAH,right?
I was correct in my statement, and yes, your statement is also correct. Adding two AA, 1.5v, 2,500mAh batteries in parallel will keep the voltage at 1.5v but add their capacities to 5,000mAh. Capacity effectively is mAh. mAh stands for milliamp hours, as a way of describing drain over time. Capacity can also refer to current, which is simply amps, A.<br><br>I threw together a quick picture in photoshop to illustrate how it works.
But I was taught in kindergarten that Series=voltage divider in ratio of resistances<br>Parallel =current divider in ratio of resistances<br>wat about that?<br>I am not pointing out anything wrong but trying to learn something.<br>not arguing but trying to turn this into an informative debate.<br>Sorry If I hurt you in any way<br>:P
Your are correct, but note that those statements apply to the wiring of resistors together. Demand from the LEDs (in terms of volts and amps) remains the same, no matter how much power you provide them, they will take as much as they can use. The LEDs conduct through one another in series, so yes, with each LED in the chain a bit of power is lost through light being emitted. This becomes a problem when you go beyond three LEDs, where the fourth can be noticeably lower than the first. Within just two LEDs, the loss of current from LED to LED is low enough to not be noticeable.<br> <br> As far as series being a voltage divider, and parallel being a current divider, yes, that is accurate in both terms of supplying power from a power source (generally that refers to batteries), and the wiring of resistors. It works both ways, not simply reducing as in division. If you add power sources (batteries) in series, the voltage *multiplies* (or you could say, divides by a ratio below 1:1) If you add power sources in parallel, the capacity for amperage *adds* while voltage remains the same. This is very useful when trying to get extended battery life from your power sources. Here is an example.<br> <br> Let's say you have a Luxeon LED Star that runs at 3.0v and 700mA. You have two AA batteries, each which puts out 1.5v and has a capacity of 2,500mAh (milliamp hours). If you were to add the two batteries in series, you would double the voltage at the cost of halving the capacity. So you would get 3.0v but now only 1,250mAh. If you have four AA batteries, you can have the the benefits of both, at the cost of greater physical size. If you have any more questions, feel free to ask.<br>
I dnt really agree with 18*20=360ma thing<br>With 12 V DC u connect 4 LEDs in series,right?<br>so they share the same 20mA<br>So technically every 4 LEDs share 20mA.<br>SO u could run about 18*4=76 LEDs on that thing.<br>Correct me if I am wrong
Power drain does not work like that. For one, the LEDs are in series of two, not four, which makes a large difference on the amount of stress put on the resistor. Second, the resistor chosen with the ledcalc calculator has been calculated to allow two LEDs in series to receive 20mA each, so in reality, the resistors are allowing 40mA through, in which each LED consumes 1/2 of the power.<br> <br> The hard limit for how many LEDs are allowed is calculated in watts. To calculate watts, it's simply amps times volts. So if your power supply pumps out 350mA at 12v, you have 0.35A * 12v = a 4.2W power supply.<br> <br> Let's count the drain for one LED, a green 5mm running at 3.2v and 20mA. So 0.02A * 3.2v = 0.064W. Now, let's divide the drain of an LED into the capacity of the power supply, which is 4.2W / 0.064W = 65 LEDs. 65 is the ideal limit, in reality, due to heat and resistance and other inefficiencies, power supplies need a bit of buffer room, so let's just cut off a few LEDs, and say the realistic limit is 60 LEDs.<br> <br> I hope that makes sense, if you have any more questions, feel free to ask.<br>
<br> i was wondering if a 12v 1amp dc plug would work if im hooking up 5 bars together<br>
To measure maximum power possible by your power supply, you need to measure everything in Watts. A Watt, is simply volts * amps.<br> <br> So if you have 18 LEDs on your light bar, with each LED running at 20mA (milliamps) and 3.2 volts.<br> 18 LEDs * 20mA = 360 mA.<br> <br> Then let's turn that into Watts<br> 3.2v * 0.36A = 4.32 W.<br> <br> For five light bars<br> 4.32 W * 5 Light Bars = 21.6 W<br> Realistically, we want some buffer power since real electrical drain isn't perfect, let's just add 5 Watts to be safe. Thus, <strong>26.6 Watts</strong> is our power drain.<br> <br> <br> Now for what your power supply can put out,<br> 12v * 1 Amp = 12 Watts.<br> <br> Sadly, that power supply cannot provide enough juice to five light bars. It will realistically be able to light three at full brightness, and at three, it will become extremely hot (like, burn your finger hot, which is bad). So the safe amount for that power supply is two light bars.<br> <br> <br> If you want a cheap power supply that can handle a ton of light bars, go find a laptop power supply, They are usually in the range of 50-75 Watts, and can be found for a couple dollars at a Goodwill, or bought on eBay for $13 including s/h.<br> <br> Good luck.<br>
Great idea and tutorial!
You should add ebay.com as a source for most of those items. I know leds can cost about $4 for 100 with free shipping.
Both HKJE and LEDHK that I linked to on part one take you to their eBay sellers stores. They are my favorite sources on eBay. Thanks for the input.
oh sorry i didn't see that there. I just read the first part that said $10 for 100.
i love doing light graffiti!
I'm intending on using around 10 LED's in series for making an LED music box. It has a TIP 31 transistor and is plugged into audio jack. But I have a power supply of 12V, 600mA. Do you think its enough to run all these LED's??
It is not possible to wire 10 LEDs in a single series. You can chain them at a max of 3 per series for the voltage you are using (12 volts).<br> <br> As far as calculating the capacity to run your LEDs, I'm going to now assume it's in series of 2 (2 * 5 = 10 more cleanly than three series and a single). Using the LEDCalc.com calculator and punching in your numbers, you should use a 330 Ohm 1/8 Watt resistor for each series of two LEDs.<br> <br> One series of two LEDs uses 0.149Amps when running at 3.2 volts (blue, green, or white LEDs). We will calculate Watts, since it is easier to measure max capacity that way than when voltages are so different (12v vs 3.2v). A Watt is simply volts * amps.<br> <br> Your power supply is 12v * 0.6 A = 7.2 Watts<br> A series of two LEDs running on a 330 Ohm resistor is 3.2v * 0.149 A = 0.48 Watts.<br> Five series of two LEDs = 0.48 Watts * 5 = 2.4 Watts<br> <br> So you've got 7.2 Watts as your max, and ten LEDs use up 2.4, you have lots of spare room to work with.<br> <br> To put it simply, you have a ton of extra power.<br> <br> You could also have gone to ledcalc.com like I suggest in my guide, punched in the numbers, and it would provide you with everything you need. Good luck, I hope my math wasn't too confusing.
Hey, I knew what it meant by connecting in 'parallel' but I just understood how to do it by seeing this link http://www.theledlight.com/ledcircuits.html . Please correct me if I'm wrong in the next statement. I can connect as many LED's as I want using 'parallel' method(say 15) and adjust my adaptor to 3V and it would work? Do I still need to add resistors to be safe or is it safe enough. Regards, Ibtassam
For parallel wiring, yes, you can connect as many LEDs as you want with only two wires and one resistor.<br> <br> With the single resistor for the whole LED chain, each additional LED puts extra strain on the resistor. The size of the resistor needed accelerates pretty quickly, going beyond twenty or thirty LEDs will require a pretty huge resistor.<br> <br> I punched your numbers into the LEDcalc.com parallel calculator. It says you will need a 47 Ohm 2W resistor to power ten, 3.2v LEDs. 3.2v is for blue, green, and white LEDs. For 15 LEDs, it's a 39 Ohm 3W. If you're using another color, like red or amber, which generally run at 1.9, you would use a 56 ohm 2 Watt resistor. These numbers are &quot;ideal&quot;, in reality, when buying, pick the closest numbered resistor you can find. As long as all the LEDs have the same voltage requirement, they will all be the same brightness. However mixing colors will cause changes in brightness, if you set your resistor for 3.2, any red LEDs along the chain will become about 30% brighter than normal [called overvolting, a nice trick for flashlights].<br> <br> At this point, you're using low-power 5mm LEDs. When you get to large LEDs (like Luxeon Stars, check them out, they're a lot of fun) the power requirements increase drastically, and so does the sensitivity of the resistor. I've run a bicycle headlamp with four, 5W Luxeon stars, where a change of 0.5 volts [since I wanted an overvolt mod] can sometimes change your resistor from a 3W to a 5W or 10W.<br> <br> <br> <br> You must <strong>always</strong> use a resistor for LEDs, except in very special cases (like a 2032 battery). You can't really &quot;adjust&quot; a power adapter, since its output at 12v is just how it's built. You can however, choose a different kind of resistor. Parallel only uses one resistor, and as far as safe, the danger is that the LEDs burn out and don't turn on, rather than something horrible like them melt or burst into flames ;-D<br>
Woah! Those were SOME led's! Just saw a video of this Luxeon thingie, It's brightness is beyond it's tiny little size. But a bit too fancy for me atm. Thanks for letting me know about the resistance in advance. Because otherwise I was thinking of finding out the actual voltages of my power supply and LED(Clear blue one) by using a multimeter(which I don't own, so would've asked the shopkeeper to measure it for me) and then using ledcalc.com to find the resistance. And, yes, 15 LED's is just about the number I was thinking about, since in parallel I can now connect a hell lot of LED's(more brightness, yayy!!). So I guess, I just go ahead and buy me one 39 ohm 3W resistor?(or any number near it) [Btw, what supply voltage did you assume for the 15 Blue Led's?] And my last question is, related figure posted below, Do I imitate this figure fully( same figure from the parallel section of ledcalc.com) or do I have to make any other change? I had a hard time searching for plexiglass today but found a neat ready-made hollow plexiglass structure for the lights. If the whole thing works out, It'll be the coolest thing I've made. So excited : ] Thanks for assistance! Regards, Ibtassam.
Yes, you should just buy a 39 Ohm 3W resistor online, I suggest eBay, my favorite store is Resistors Plus (search on google). That parallel diagram is exactly correct. Just extend it to the right for 15 LEDs instead of three. If you need plexiglass (acrylic), or polycarbonate tubing, I suggest TAP Plastics, they have square and round tubes which may be what you're looking for.

About This Instructable




Bio: 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 ... More »
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