Step 6: Building the circuit

Picture of Building the circuit
Many people get scared when they see all those weird circuits with those symbols on it. Having no clue what they mean.
That's why I made a instructable friendly circuit image :) See photo 1.

1. Make sure you have all the materials to make the circuit. And enough electrical wires to connect all the components.

2. Before we build the circuit, we first need to put the audio cable through the whole in the back.

3. Build your circuit, and test it out.  The best way to test it is through your audio output from your computer. Make sure the audio on your computer is set to 100% and then test it.

CircuitThe positive pole from the adapter goes to the positive leg of the first LED. Next the other 5 LED's follow. Hook the negative leg from the first LED to the positive leg of the second LED. Hook the negative leg from the second LED to the positive leg of the third LED, and so on. The negative LED from the last LED goes to the center pin of the TIP31.
Then hook the right pin of the TIP31 to the negative pole of the adapter.
All there's left now is to hook up the audio cable. Hook the red or the white wire from the audio cable on the left pin of the TIP31. And connect the ground wire from the audio cable to the right pin of the TIP31.

For better details please see photo 1, the circuit.

4. If your circuit works, solder all components together so the circuit stays together nice and strong and wont fall apart.

When done with these steps it's time to finish up!

If you have trouble getting the circuit to work, you can try to set it up first on a circuit board.
Carlosserious was so kind to make a how-to video on making the circuit, click here for the video.
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gokuli2 months ago

thanks..can i connect the circuit in 230 volt ac by using ac to dc circuit.....? pls give me the ac to dc circuit.. my email:gokulindianur8@gmail.com

tamlani1 year ago

hey plz help me out. i am using 5m led flex roll with 12v adapter. plz guide me how many transmitter would i need as i am using one TIP31C but it doesn't work...

dinox4 tamlani8 months ago

i also could only find Tip31C it seems it needs higher input to work, mabye 5 watts speaker amplifier to work properly in my case...

make sure to know your transistor before applying the circuit which is base , emitter

and collector ...so its better to use tip 31 transistor ...coz above picture is easy to follow....

I've having some troubles with this. When I connect my LED to the farthest left pin of the TIP31 I get some constant light but when I connect it to the middle pin nothing happens. I'm using the headphone part from old apple earbuds if that makes a difference.
I'm having the same issue. Constant light on either side pin and no light on the middle pin. I thought maybe it was the transistor, but I changed it out for a new TIP31 with the same results. My schematic is slightly different. Any thoughts on why this might be happening?
tamlani dseter1 year ago

heyy did u find any thng good relating to your problem??

i am having the same problem... i am using 5m led flex roll and 1 transmitter TIP31C and a 12v power suply...plz help me out if u know how to deal with that. thanks

are u sure your looking at the front of the tip 31 when connecting the wires. you might have the right confused with the left causing problems.
csshandy1 year ago

if you use lets say for example a car stereo and try and connect it to a high or low input of one of the channels it can cause some problems because the stereo is using the 12 volt car battery and the tip31 is aswell it can create a short circuit because the sound out of a stereo is A.C meaning the wire on the ground side can shift from low to high causing a short circuit the only way I can think of around this is adding a 1k resistor between the power for the tip31 so that it stops this however haven't tested it, this is my understanding of it so if anyone has anymore input on this feel free to give advice I will test this theory out tomorrow and post back.

bemory1 year ago
is it possible to add this to an individual speaker instead of using a headphone jack it seems like it, I am just unsure
TTomoTT1 year ago
Connecting Left or Right audio wire to Tip 31

I found that my lights were not working but couldn't find anything wrong with the circuit so I switched the Red (Right Headphone) wire with the Left (White Headphone) wire on the left leg of the Tip 31. Low and behold it works!

Funny as you would of thought they would both have the same output. Hope this helps someone at their wits ends.

Thanks for the brilliant tutorial Motadacruz
jensenaw2 years ago
Hi, Can i use tip31a instead please?
bkoo2 years ago
Hello, on step 6, in photo 1, 4, and 5, the LED's are connected on a metal piece altogether. What is that piece of metal that the LED's are connected on and how do I get it? Or did he just make it? Or how do you make it? Because if I connect the LED's just with wiring, the LED's will be all over the place and will look quite ugly when the lights are flashing inside of the box. I would like the LED's to be neat. Somebody please help! :) Thank you!!!
BrandonHall2 years ago
any ideas how to make this either a 120V (wall socket) adapter or have it powered off one battery because i have 6 strips of the LED's that you would get at Pep Boys that have their own 12V source per 2 strips i wanted to have it run off one battery and or a 120V socket please help? also i don't want to sacrifice brightness to the three sets
gtgm_1102 years ago
How would you add a simple toggle switch on if you wanted that? I'm new to electronics and circuitry so thank you for the help.
just take one of the positives (or negatives) cut the wire and add the switch in between that cut wire kind of like a normal light switch just interrupt the power supply.
bhallett2 years ago
is there a way to attach 6 12v strips of the walmart led flex lights to one power source with out blowing out the first line and having it run off one two or three tips help!!!
ndelic2 years ago
Can be TIP48??
Laiman2 years ago
I have got a chain light of 4v lights powered by 230v, with no small circuitry whatsoever. How can I join these two ideas together? The led box based on tip31 transistor and the chain light. Is it possible and if yes how?
kushal9012 years ago
I have a set of LED lights that run through the mains at 240V (UK). Would it be possible to use this same set up on the negative wire? Would I need to use a different transistor?
nhan572 years ago
Hi i'm having a problem, can someone help me???
Having one TIP31c
I followed this picture but instead of using a battery I just use my arduino Diecimila powered on the USB and one led without resistor, but when I put the right wire of the jack and the ground of the right wire on the TIP31C sometimes it just turn on and keep the light or nothing appear and then when I start the music nothing is there...
please some ideas????
bswt2 years ago
i'm getting noise through my speakers what kine of cap should i use
xxullixx3 years ago
Hi not much of electronica, but I was wondering if this circuit could work:

well, it might work, but some micrphones will give a very low signal that would be insufficient to open up the TIP 31 completely. The TIP31 has a very low gain (around 20).
So if you want to have 20mA through yr LED's you will need to input 1mA from yr microphone.

I am not sure all microphones will be able to deliver that current: modern microphones have an output voltage of perhaps 5 mVolt, but i am not sure how much current they will be able to deliver in a TIP31's base.
It won't hurt trying the circuit though :-)
If it does not work properly, you could use a BC547 to make a Darlington circuit with the TIP31 and use a proper base resistor for the BC547.

Or make a simple amplifier circuit with a BC547 (emmittor to ground, 10kResistor between Vcc and collector, 22k resistor between base and collector, 1 k resistor between base and signal. Lead the signal from the collector to the base of the TIP)
Can you wire this in parralel please respond because otherwise I cant light my strip lights because they are 12 volts every two and I have four and won't light in series
yes ofcourse yr LED strips can be in parallel. Do you mean that per 2 they are 12 Volts? (so 6 Volts a piece?). In that case put two in series and then put those two strips that are in series parallel to eachother. If they are the same brand and type this shld be ok.
eckoview053 years ago
I am using this in car. I have it connected to my line out converter and when i turn the volume up really loud i blow my leds. If i were to put a pot or fixed resistor on the positive side of the audio input would that prevent them from blowing?
Th e LED's have no current limitation whatsoever, so if their combined forward voltage is less than 12 volts, the current could get too high. It is well possible that under normal conditions the TIP 3 is not opening up completely, thereby limiting the current, but when fed from a speaker, it could allow the TIP31 to open up completely and if yr LED's then have les than 3 volt forward voltage, it is 'boom'

There is a solution though, as manas.g29 already suggests: a resistor. To calculate that you need to know the exact forward voltage of your LED's. If you do not know, check here: http://www.instructables.com/id/Determining-Forward-Voltages-of-LEDs/
Now suppose you come to a combined forward voltage of 10 volts and your battery is 12 Volts (beware, sometimes they can be 13, or 14) that means you have to 'get rid' of 2 volts.
Suppose that you have regular LED's (so no high power), these can take 20mA. So you will need a resistor of 2000/20 (2000mV/20mA)=100Ohm and it should have wattage of 2x2/100=0.04 Watt, most common resistors being 0.250W so that shld be ok

Now there is another problem. Since the LED's are in series and if they are not the same -especially if tey are of different color- They may have different forward voltages. That means that though the total forward voltage over all 4 LED's may be ok, one or more LED's may still have a Voltage and thus a current that is too high.

So if you are using different color LED's I would not put them in series, but parallel, each with their own series resistor. Ofcourse this means more power loss in the resistors, but that is better than blowing yr led's.

The best way would be to make a current driven circuit in which the current is maxed to say 20mA and varying with the audio input. That ofcourse requires a few more parts (but not really much more.

The enclosed picture gives an idea of how to do that. Ofcourse you do not need a FET, a powertransistor (like the TIP31 or a 2n3055) could be used as well
wizzzz2 years ago
hey any alternate for tip 31
RexHex2 years ago
Im using this circuit for my girl friends birthday gift but it just stopped working before i started the aesthetic aspect of the design :( . I have 3 potentiometers (POT's) each connected to a LED. 1)red 2)blue 3)green. so each POT controls the overall color of the design.

I have a switch that turns it from being on solid to turning to this circuit. Last night it was working just fine when I switched it over to the "music flash" circuit but today its just off when I do the switch... I did loads of test. probably 3 to 4 hours in between my classes to figure this out but just cant come up with any solution other than I must of blown the transistor. Any ideas why this might of happened? im using a 6volt battery source making me think this should not blow.
What software did you use to draw out the circuit?
kfryers3 years ago
Can someone help me out?
Im trying to implement this into my car, but not sure how to? Because this is using a 3.5mm audio jack to plug into your ipod or computer, so how would i do this in a car because there is nowhere to plug a 3.5mm jack?

So basically this wiring diagram is how i want it to be in my car, The top left box symbolises the music box (This circuit that makes the LEDs flash) and basically im having red green and blue LED strips in each footwell so thats why you see two of each colour, and each footwell has a 3 toggle switch so the person sitting there can choose the colour, and then the other switch at top left is going to be a 3 way switch so i can choose whether i want the music box on (so LEDs flash to music) or off (so LEDs just stay on, no flashing to music)
xredvortex3 years ago
Ok i have a problem with the audio wires. one of them has red and gold wires while other one has green and gold. im assuming its right with ground and left with ground? I tried doing red with opposite wire's ground and vice versa but still doesnt work. help!
i had the same thing. just twist the red and green together, an the gold/copper color together. then just treat the red and green as one wire and connect them to ur left pin pn the tip31 chip and follow the scematic in the same way for everything else. (hope this makes sense!)
AlexT20103 years ago
I have done the exact diagram as above, except with one Led just to try it out. It works when i use a wall charger for a phone, 120-110 to 5v and it works perfectly, but when i try this on the battery in my car nothing happens, Any ideas?
if your going to attach this to ur car battery u need to have resistors so that u dont blow out ur led's causing them to break.
your power input is too high to properly run the LED. you can only have so much power going into one before it wont work. Try adding more leds or find out what resistors to add to it. try using this website to calculate it http://led.linear1.org/led.wiz
bunso3 years ago
can it use any players? like chine mp4 or mp3? can this player can light up the led?
Please someone explain me. I am a rookie in electronics. I was always amazed by computer programming until i changed every single light source in my car with leds and met the world of electronics.

I am trying to understand how transistors works. I read this article http://www.satcure-focus.com/tutor/page4.htm.
But in the music led case wasn't supposed that base has to be connected to 3,5mm so that the music signal works like the plunger in the example which change the flow from baterry to leds????
why the music plug is in collector - emitter legs?????
raja123 years ago
hi, i have read all the comments but still not found out how to connect this with my laptop with the sound and light both goin together. PLEASE HELP ! with a clear and simple answer as im not good with electronics ..thanks :)
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