Portable Disco V2 -Sound Controlled LED's




Introduction: Portable Disco V2 -Sound Controlled LED's

About: I've always liked pulling things apart - it's the putting back together again that I have some issues with!

I've come a long way with my electronics journey since I made my first portable disco. In the original build I hacked together a circuit on prototype board and managed to build a neat, little pocket disco. This time around I designed my own PCB and worked out a way to have the LED's dance with either a mic or directly from a music source. Having the LED's dance to a direct music source was an afterthought so the board for that I had to use prototype board. However, I did design one in eagle which I have made it available in the Instructable. Version 3 will be even bigger and I'm hoping to incorporate bluetooth as well.

I'm really happy with how this portable disco turned out. It looks and works great and the opal acrylic diffuser really gives the LED's some depth.

The build isn't necessarily a hard one, however, you'll need to know how to solder and have a basic knowledge of electronics. I have also been using my dremel as a small router and used it in this build to cut channels in the wood for the acrylic.

Step 1: Parts

Dancing LED Boards & Components

1. Dancing LED circuit boards. You can find the link to these in the next step. There are 2 boards that you will need to get, one is the main board and the other is an extension.

2. 4017 IC X 2 - eBay. Buy these in lots of 10

3. IC dip Socket X 2 - eBay. Buy these in lots of 10

3. 20k Resistor X 2 - eBay

4. 100R Resistor - eBay

5. 2M Resistor - eBay

6. BC547 Transistor - eBay

7. 100nf Capacitor - eBay

8. Condenser mic - eBay

9. Right angle pin header - eBay

10. Right angle female pin header - eBay

9. LED's. I used 2 different types of LED's. Some were diffused and some weren't. The reason being, I wanted different sized light patterns to appear. You should experiment yourself to find which works best for you.

Normal LED's (assorted) - eBay

Diffused LED's (assorted) - eBay

Sound Module

If you also want to be able to plug in a speaker and iPhone and have the LED's dance to music directly, then you will need to also make this circuit

1. Board - You can find the link in the next step. I ordered one but couldn't wait so just made one on a prototype board.

2. 386 IC - eBay

3. 10 uf Caps X 2 - eBay

4. 220 uf Cap - eBay

5. 5K (or 10K) Potentiometer - eBay

6. audio Socket X 2 - eBay

Other Parts:

1. SPDT switches X 2- eBay

2. Wire

3. Pot knob - eBay

4. Opal acrylic diffuser - eBay

5. Hardwood edging 40mm x 8mm - your local hardware store will have this. You'll need about a meter length.

6. 3mm ply wood - your local hardware store will also have this

7. Mobile or li-po battery - eBay. You can prob just pull one out of an old mobile you have lying around

8. Charging and voltage regulator module - eBay

Step 2: Schematics and PCB Files

I have started to design my own PCB's using Eagle. If you are interested in getting into designing your own then I highly recommend Sparkfun's tutorials on schematic and board design. They are easy to understand and you'll be making your own boards before you know it.

You can't attach zip files to Instructables pages so I have linked all of the files to my Google drive. The zip file has all of the gerber files which you need to get the PCB printed. Just download and save the gerber file and sent it to your favourite PCB manufacture. I use JLCPCB but there are plenty of others you can use.

PCB Boards

Google Drive Link

As you can only design boards at a certain size in Eagle (unless you pay), so I made the boards module. There is a main board and then additional boards which can plug into the main board. I don't know how many you can plug into the main one but I reckon you could easily add 3 or 4 to the main one, maybe more!

You will also need the smaller audio board that I designed if you want to be able to plug the LED's directly into a audio source. I have also included the gerber files etc in the link above.

Step 3: Routing a Slot in the Wood and Cutting

To start, you'll need to rout a slot in the wood to secure the acrylic into. You could always just by-pass this whole step and stick the acrylic to the front of the wood if you don't have a router.


1. Secure the piece of wood that you are going to rout with a couple of vices

2. attach the routing tool and bit to a dremel (or just use a normal router if you have one) and slowly cut the slot into the wood.

3. Once the slot has been cut, measure and mark the pieces that you will need to cut to make the box. The lengths I used was:

L = 75mm

L = 310mm

4. Cut the wood and if necessary, sand the ends. Place the equal lengths of wood together and make sure they are the same. If not sand until they are the same lengths.

Step 4: Cutting the Acrylic and Making the Back

Now that you have the sides, you now need to cut a piece of the opal acrylic to fit into the slots you just cut with the router. You'll also need to make a back for the box as well and then glue it all together


1. You need to work out how big to cut the acrylic. The easiest way I found was to place one of the side pieces against a longer piece and place a ruler into the slot.

2. Once you have the measurements, cut the acrylic. I have a band saw which works a treat to cut acrylic but you could also do it with a fine tooth saw.

3. Test to make sure that the acrylic fits and you can add all the pieces of wood without any gaps.

4. Add some wood glue to the sides and clamp together overnight.

5. The back is made from 3mm ply wood. Measure and cut a piece for the back. make it slightly larger than needed as you can always sand it down to make it flush with the box. Add some screws to the back first before final sanding so it doesn't move about

Step 5: Making the Audio Circuit

As I mentioned earlier in this Instructable, I did design a board for this but the mail has been super slow due to COVID. I couldn't wait any longer so I just built it on prototype board. The board and gerber files though can be found in Step 2. I'll go through though step by step how to put this circuit together. It is needed if you want to plug in music directly into the LED's from an audio source


1. First, add the 386 IC. Use a dip socket as well as it's always good to be able to take out the IC, esp if it is faulty.

2. Add a 10 uf cap to pins 8 and 1 on the IC

3. Connect pin 4 to ground and pin 6 to positive

4. Add a 220 uf cap to pin 3 . The other leg will be connected to the left and right audio jack sockets so connect this to spare spot on the prototype board


Step 6: The Dancing LED Boards

As you can see, there are 2 different boards. The first is the main board and has most of the components on it, the 2nd is an add-on board and only has a 4017 IC and some LED's. You can connect this board to the main board like an extension. In the schematic and board link in step 2 I made a slight change to the boards so you can now connect them together at a few different points, making them more module.


1. The first thing to do is to add the pin headers to the boards.

2. Add the male ones in first to the main board

3. Next, place the female one into the top of the add-on board and plug it into the male headers

4. Add some solder to the top section of the pins to secure them to the board. The reason why you do this first is to ensure that the boards sit flat

5. You can then turn the board over and add some more solder. The pins on the female header only just go through the board as the male ones sit up higher then the female ones

Step 7: Adding the Components to the Boards

This is very straight forward and you only need a few components to complete the boards


1. I always like to start with the resistors. You can add them all into the board and solder them at once. Plus it means the board sits flat and the resistors won't "ride-up" when you are soldering them.

2. Next add the header socket for the IC

3. Add the cap and transistor next

4. Once the components are done, you can then add the LED's

5. Lastly, I would test to make sure the board works. add a mic to the mic solder points and some power and talk into the mic. You should see the lights dance about. If not, go over the board, check your solder joints and components to make sure everything is correct.

6. The other add-on boards are even easier, solder on the IC and LED's. That's it! Plug it into the test board and make sure it works as well. It does? Good! You can now move onto the next step

Step 8: Sticking the Boards Down to the Back of the Box


1. First, mark out with a scrap piece of the wood from the box, where the box touches the back section. This will help you know where to add the boards to the back section.

2. Add some good quality, double sided tape to the back of the boards.

3. Connect them together and carefully stick them down to the ply wood.

4. Lastly, you will need to add 2 SPDT switches as well to the back. One of these will be for on/off and the other to switch between mic and audio input.

Step 9: Adding the Components to the Box

Now that you have your box and electronics completed, the next step is to add some components to the box itself.


1. First, you need to add the condenser mic to the front section of the box. You could possibly add this to the side of the box if you wanted to keep the front section nice and clean but i figured it would be the best place to pick-up the music.

2. You need to be careful when drilling acrylic as it my chip. I used a stepped drill piece to do this and it seems to reduce the risk of potential chipping.

3. Once the hole is drilled, push the mic into place. add a dab of superglue if necessary to hold it into place

4. next, drill a couple of holes for the audio sockets and push them into place. I made the holes just large enough to fit them nice and tightly. Add a little superglue if necessary to hold them in place

5. Next, you need to connect the left and right of both audio sockets together along with the ground solder points. I used some resister wire to do this. All you are doing here is really making a way to be able to connect a phone and speaker together. the input on the audio circuit will also be connected to them as well later on. To save on wire, you can also connect one of the legs from the mic to the ground on the audio jacks

6. Drill a hole for the pot and secure it with some superglue.

Step 10: Wiring the Boards & Components Together and Adding Power

Wiring always is hard to show in images so I have also provided an image of how to wire-up the switches so you can switch between the mic and audio input.


1. First thing to do is to connect the left and right on both of the audio sockets together along with the ground.

2. I connected the mic ground as well to the audio ground just to save on having to use a wire and connect it to the ground on the board.

3. Connect the left and right audio to the solder point on the audio board. There are 2 solder points on the board but you only need to connect them to one.

4. Add a wire from output on the audio board to the first solder point on a switch

5. Solder a wire from the mic solder point on the LED board to the middle pin on the switch and then solder a wire from the actual mic to the last pin on the switch. This will then allow you to switch between audio and mic

6. For the battery and charger, you can check out this 'ible I did which will show you how to connected these together.

7. Add the battery and charging module to the base of the box. You'll need access to the micro USB so you'll need to make a hole in the back panel and align the micro USB to it.

8. Once everything is wired-up, turn it on and check that the mic and audio inputs work.

Step 11: Finished. So How Do You Use It?

Last thing to do after you have tested is to close up the back. I just added a few screws to hold this in place.

Now that it is done, how do you use it and what is the pot for?

First, turn it on. Once it is on, hit the other switch so the mic is activated. Now if you play some music or make some noise, you should see the LED's react.

Next, plug in a portable speaker to one of the jack sockets, and add a music source like a phone to the other. As you have connected the sockets together, all you really are doing is plugging in the phone to the speaker. However, they are also connected to the dancing LED board so this allows you to hear music whist the LED's dance about.

Use the pot to help find tune the LED's reaction. If you turn the pot right up the LED's will just dance about without reacting to the music. This is good if you just want to have the lights dance about without any source. turn the pot down and the lights will start to react to the music. Keep on turning until you find the sweet spot where the lights are moving in the way you want them to.

What next?

Well if you have built this one successfully, you can try your hand at extending the boards and making an even bigger one. Remember they are module so why not try and add 3, 4 or even more and see what happens. You could end up with a huge panel which would look awesome on a wall.

Thanks for checking this 'ible out and happy building.

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    10 months ago

    Thanks mate again for this fun project!

    These are 8 of your boards doing some 4-to-the-floor!


    10 months ago

    I only managed to get two boards (main+addon) to work...
    Adding more addon-boards sadly does not light up the 3rd one and the remaining 2 boards stop functioning though they light up...
    I tried that with several boards, has anyone ever tried daisy-chaining them...
    Maybe I'll need another of these boards with a transistor?

    Thanks again for this wonderful project :-)


    Reply 10 months ago

    I recently tried to also string more than 2 together and worked out that I had the connectors incorrectly orientated! If you want to add another board, you'll need to add some jumpers and connect the boards as shown below. Bit of a pain I know and I'm looking to fix the schematic's up soon.
    Glad to see you get it working with a couple boards though - hopefully this helps to get the rest of them going!


    Question 1 year ago

    Can you put circuit ticks on you


    2 years ago on Step 11

    Still some questions:
    1. You should have an overall schematic showing how all components, including the ones not on a PC Board, connect to each other. I see you tried to convey this information in the text of the 'ble (instructable), but it lacks clarity. For example, the audio output from the amplifier (pin 5 of the LM386) is labeled "LED-IN", yet nowhere on the schematics is there another pin marked "LED-IN". From reading the 'ble, I gather it really goes to one outside terminal of the switch, and, when the switch is in the correct position, out through the center terminal to the unmarked pin on the Main PCB that leads to the junction of the 100nF and the 20K resistor. That pin is the Mic+ terminal, only labeled on the silkscreen, but not on the schematics.

    2. The power pins of the 4017 are difficult to read on the schematic (Power to pin 16, ground to pin 8).

    3. The pot: Did you wire this as a 2 terminal device (ignoring the one outer terminal, or jumpering one outer terminal to the wiper) or as a 3 terminal device (outer terminals to audio input and ground, with the wiper connected to pin 3 of the LM386) in the schematic?
    4. Since all of the display boards source current from a single 100 ohm resistor, there probably is a limit to the number of LEDs this design could drive. Why not add a 100 ohm resistor on each display board. Then you would not need to carry that signal though to all display boards.

    5. Why not add 2 more connectors (one middle top, and one middle bottom) to the display boards so you can expand the display not only in the horizontal direction, but also in the vertical direction?

    Please take this in the spirit it is offered, as an effort to improve your 'ble, and not denegrate your design. I appreciate that you took the time not only to post this design, but to NOT over-engineer it (like using and arduino). Simple is beter sometimes.


    Reply 2 years ago

    Howdy. Always happy to take on suggestions! Here's the changes I made:

    - I have updated the schematic and included a 100R resisitor on the additional boards. - Changed the descriptionon the audio board to say "Mic-in" which should make it a little clearer.
    - I'd already additional headers to the boards (good idea though) as per the schematic and boards. This way you can add them on the top or bottom as well.
    - In regards to the pot, there is a 1 and 2 on the board which means you connect pins 1 and 2 of the pot to these solder points.

    Thanks for the input


    Reply 2 years ago

    Thanks for the quick response.