In this Instructable I show how to make a simple Vu Meter Speaker.
I thought about this when I found old parts of a radio. Thought it would be fun.
Step 1: Materials
-12 LEDs (6 green, 4 yellow, 2 red)
-6 resistors (220 ohms)
-Heat shrink tubes
-Used Speakers (Mine is from an old (dismantled) radio)
Step 2: Speakers and EarPhones
First, I retrieved my speaker from an old dismantled radio I had and found a pair of broken earphones.
To connect the speakers to the earphones, I cut off the actual earbuds, and carefully removed part of the sleeve of the two "branches" of the earphones to reveal about 1 cm of the two inner wires.
I then used two wires and soldering materials to connect one of the "branches" to the speakers. I soldered the inner wires with the wires. On the speakers there are two spots where to connect the wires, the direction doesn't matter. After it was connected, I made sure the speaker worked with my mp3 player.
For the other "branch", I connected two wires, one red on the positive inner wire and one black on the ground inner wire. This will be connected to the Arduino later
I then protected my soldering by placing a heat shrinking tube on each connection and a bigger one both pair of wires joined together.
Step 3: WoodWork
I decided to build the casing for my speaker I used scrap pieces of plywood.
For the face of the casing, I used my speaker to draw its outline on the wood and drilled out the hole with the correct size hole-saw. Although, I used a hole-saw slightly smaller than the actual speaker so I would be able to glue it easier later. I then cut my piece to make it in a square.
For the LEDs, I found the right size of the drill bit by testing them on a random piece of wood and placing an LED in them. Once i found the drill bit that provided the good hole size for my LEDs, I drilled 12 holes on the sides. (6 on each, aligned together of course).
For the sides of my casing, I cut two thinner pieces into triangles with the right height so they would fit with the face of the casing. (The length didn't really matter)
Step 4: LEDs
Now, before painting and gluing the wood together, I made the circuitry for the LEDs.
I used the face of my casing to place my LEDs while connecting them together.
I used 12 wires, preferably choosing one color of wire for each color of LED. (As you can see, they unfortunately don't fully match the color of the LEDs, but still :p). In my case, the red LEDs had blue wires, yellow had yellow, and green had white.
First, I soldered the cathode of each side of 6 LEDs together. Then, with a wire I joined the two side's anode together. For the anodes, I connected each with a wire, making sure the wire is the same color for the same colored LEDs. Then, I connected each pair (6 total) of LEDs with a 220 ohm resistor. Finally, I connected each resistor to a 6 pin header. I connected the pairs in order to the pins. (Not so pretty but it works eh)
I used heat shrinking tubes to cover the resistors and prevent faulty connections between them)
NOTE: a pair of LEDs are two LEDs (one on each side) at the same height position!
Step 5: Paint
To paint, I removed the LEDs from the casing, and used dark brown spray paint.
I applied one primer layer and 3 paint layers on each piece of wood, and waited patiently as it dried. (but not really... I did step 7 while it dried)
Step 6: Gluing the Speaker
I used wood glue to glue my speaker.
The two triangular sides were glued on the back side of the front, by the edge. As for the speaker, I applied glue on its side, and placed it in the hole.
And I waited till it dried.
Step 7: Arduino
The code for the Vu meter, is pretty simple.
As the headphones send change in voltages, it can be read by an analog read pin of the arduino. So, I used an analog pin as input to read the data from the headphones. For the LEDs, I used 6 digital pins as outputs.
In my code I set 6 values, for each level. And depending on the value read by the analog read compared to the 6 values, the corresponding LEDs light up.
On the board, I connected the red wire of the other branch of the earphones to the analog read pin A0. The black wire of the branch was connected to the ground. I connected the 6 pin header in the pins 13 to 8. (13 being the red LEDs). I also used the breadboard although it's could be done without.
*The 6 level values are changeable obviously, and a calibration setting could be added later on. (Ex: reading an x amount of analog values, finding the average, and use the average as multiple for the 6 values)
*There is a 5v input limit on the arduino pins.
Step 8: Final Touch
Finally to hide and protect the wires, I glued a piece of felt on the back.
Connected everything with the arduino and an mp3 player, and all done!
Thanks for reading!
*The quality of the sound is not great, but the purpose was to play around with the Vu meter concept