Introduction: SOLO Cup Speaker
First Prize in the
DIY University Contest
Want to be the life of the party this year? Or maybe, like many college students, you want to blast your music way too loud. Awesome. You're in luck because I've designed this SOLO Cup Speaker to bring out that college student that's inside all of us. Because, what is a party without music? And more importantly: what is a party without SOLO cups? So let's kill two birds with one stone, and get that party bumpin' with a raging party worthy SOLO Cup Speaker.
This little red cup has a huge sound. Built using a real plastic SOLO cup, this project isn't like similar cup speakers. The plastic of the cup is used to resonate bass frequencies to give this party animal some passive bass boost. Since I know that many are all about that bass, I didn't stop there. I modified this speaker's amplifier circuit to give it punchier lows with an active bass boost. Equipped with an indicator LED, internal amplifier, volume control, 1/8 inch audio jack, 2.1mm DC jack, and 8 ohm speaker, this cup is all you need to get rowdy. You can even throw your cup into your backpack with a 9v battery and bring your party with you wherever you go!
So come on, the party awaits! Let's move onto our next step to find out what you need!
Step 1: Get Some Parts, Bro!
You're going to need these parts:
-One SOLO cup
-LM368 (with socket)
-Perfboard (5cm by 7cm)
-8 Ohm Speaker
-10nF Ceramic Capacitor (Code: 103)
-33nF Ceramic Capacitor (Code: 333)
-47nF Ceramic Capacitor (Code: 473)
-10k Ohm Resistor
-Two 4.7K Ohm Resistors
-10 Ohm Resistor
-47K Ohm Resistor
-2K Ohm Resistor
-5K Ohm Potentiometer
-2.1mm DC Screw-Mount Jack
-Red 3mm LED (with bezel)
-1/8 inch Audio Jack
-Assorted 22AWG Hookup Wire
-Gorilla Glue (or Super Glue)
-Dupont Female to Female Wire
-SPST Switch (Optional for ON/OFF)
You'll need these tools as well:
-Hot Glue Gun (with glue sticks)
-Soldering Iron (with rosin)
-Rotary Dremel Tool
Step 2: Breadboard It!
Before starting a project, its best to breadboard it first. Even for super awesome party speakers. So lets start this off with some breadboarding!
Attached in the images above is a "schematic" of the circuit we will be implementing. A schematic is basically a map of what goes where in a circuit. If made correctly, they should be easy to follow so don't get discouraged! Wondering what the symbols mean? Here is a reference.
The circuit we are going to implement amplifies the low voltage audio signal coming from the input device and outputs it to our speaker. The heart of this project is the LM386 audio amplifier chip. It provides surprisingly good quality audio amplification in a small package.
(Note: There should be a speaker connected in the images of my breadboarded circuit; however, due to styling reasons I left it out. Follow the schematic if you are ever uncertain of what is correct.)
If you have trouble getting your circuit to work, check out the next few steps as they may help you see what's going on with the circuit.
If you're not satisfied with the sound of your speaker, try swapping speakers. Keep in mind that the cup will resonate the lower mid and bass frequencies.
Once your breadboard can blast some tunes, let's get soldering!
Step 3: Solder IC Socket
Alright! Now that we know what we're doing, let's get soldering. Solder your IC socket near the center of your perfboard. This will give us room to fill the holes nearby with our other components.
IC sockets are very useful in projects that heavily rely on a certain integrated circuit, since if the chip goes bad, you can just swap it out for a brand new one!
Step 4: Solder Pin 1 Connections
For simplicity, we are going to take things one pin at a time. So lets go ahead and start with pin 1. Refer back to the schematic for visual instructions.
Pin 1 is connected to pin 5 via your 33nF capacitor and 10K ohm resistor (polarity does not matter).
Great! Now we've got some electronic components on the board. Now for a little tip. I am going to assume you take this advice from now on:Make sure when you have long resistor/LED/capacitor/etc leads protruding from your board that you cut them with a wire cutter (see picture 4). If you don't remove them now, they will probably end up sitting there forever... kinda like that homework you and I are putting off.
Step 5: Solder Pin 2 Connections
One pin down, five left to go. Let's check out pin 2:
Pin 2 is connected to our mono audio input via a 10nF capacitor.
For now, let's now worry about converting the stereo input to mono. Connecting your 10nF capacitor to pin 2 is enough for this step. However, go ahead and add three male header pins to connect the audio jack from the cup to our main board. Also, add another two male headers for ground and the input voltage, as we will be using them in the next step. See the images above for more details!
Step 6: Solder Pin 3-4 Connections
Take a breather... this step is easy. Simply do the following:
Connect pin 3 and 4 to ground.
That was too easy. To make things more exciting, also add two male headers for the speaker (opposite from the audio input) and add another two headers for connecting our indicator LED later on.
Nice! Now our main board is really coming together, but we are missing a key feature... The power supply! Let's check that out in the next step.
Step 7: Solder Power Supply
Its time to take a break from the LM386 and instead focus on the board's power supply. We must go through the trouble of adding a power supply on the board because we want to be able to input a variety of voltages to our speaker to make it more versatile. A simple way to accomplish this is to use a LM7805. The 7805 is a voltage regulator. The job of a voltage regulator IC is to knock an input voltage (between a certain range) down to a constant documented voltage. This makes it so that we could give this circuit 12V, and the circuit would be just fine.
LM7805's have a simple pin out. Check out here for a diagram and further explanations.
Just connect the input ground to 7805's ground (middle pin), input voltage to 7805's input, and the output voltage will be the regulated power supply for our circuit! While you're at it, connect one LED indicator header to 5V via a 2K ohm resistor and the other to ground. Alright now we can get back to our LM386!
Step 8: Solder Pin 5-6 Connections
Just two more pins remain for us to play with on the LM386. Check out the connections on the schematic and the following textual instructions:
Connect pin 5 to ground via a 10 ohm resistor and 47nF capacitor. To continue we will need to solder three headers to the mainboard to represent the left, right, and middle terminals of our potentiometer. Connect pin 5 to our 5K ohm potentiometer's left terminal via a 220uF capacitor. Connect the middle terminal to one end of the speaker's male headers and finally the right terminal should be connected to ground.
Connect pin 6 to +5V and a 100uF capacitor connected from pin 6 to ground.
That's it for the LM386! Just one more piece and the circuit will be complete. Move onto the next step to finish the circuit!
Step 9: Sum Stereo Audio Signal to Mono
Stereo audio is an electronic signal which has two channels: left and right. It gives a spacial aspect to reproduced sound and is great for speaker systems that consist of more than one speaker. However, since our cup only has one speaker, we are going to want to transfer both the left and right channels of our stereo signal into one single channel.
This cannot be done simply by connecting the left and right channels together. Attempting that could lead to shorts and some bad phase. (Imagine if the left channel was high and the right was low). To prevent this (or at least lessen it), I've implemented a circuit I found online into the main board. Check out the schematic above for visual instructions. To sum the stereo signal into mono you have to:
Connect the left and right channels together via two 4.7K ohm resistors. Then connect their sum to ground via a 47K ohm resistor.
Don't forget to connect pin 2's capacitor to the newly summed audio signal!
Sweet! Now we have both the left and right channels of our stereo signal coming out of a single speaker. Now we just have some loose ends to tie before we start working on that SOLO cup!
Step 10: Solder and Connect Dupont Wires for I/Os
Let's finally make use of all those headers by connecting our inputs and outputs to them. Strip the ends of our dupont wire and solder them to each external component. This includes: the potentiometer, speaker, DC jack, 1/8 inch audio jack, and indicator LED.
Once complete be sure to test your circuit to make sure everything is up to par. Be prepared for your speaker's sound to be beefed up by the cup's natural passive bass/lower mid boost!
Step 11: Cut Perfboard
To make the circuit fit in the SOLO cup, we are going to need to cut off any parts of the circuit that are taking up unnecessary room. In my case, I could get rid of an entire half of the board. To cut your perfboard follow these steps:
1. Scratch the board with a utility knife multiple times.
-This weakens the board at the exact location where we want to break it.
2. Using a pliers, firmly grip the side of the board you want to keep. While keeping your grip firm, push on the other side of the board with your other hand. It should break nice and even. (See picture 3).
3. Try to put your circuit board into a SOLO cup and see if your board needs additional trimming. You could always use a dremel tool for some quick shaving.
Good news! The circuit is totally done! Now its just a matter of hanging out with that red SOLO cup for a while.
Step 12: Dremel SOLO Cup
Using a dremel tool, make room for your potentiometer, indicator LED, DC jack, and audio jack. Here are some precautions while dremeling the cup:
-Be careful not to break your cup, and make sure to have several backups just in case.
-Make sure to space out the components well so that they do not touch inside of the cup.
-For each drill hole, ensure that the component fits snug without being too loose that it could slide into the cup and without being too tight that it cuts through the plastic cup.
Step 13: Mount and Glue I/Os
If dremeled correctly, this step should be simple. Everything should fit just right and screw in nice and tight. However, since we are all human, there may be some drill holes that were too large. To fix this use super glue or gorilla glue to ensure that those components are going no where. This prevents you from over tightening screws so that there is no damage to the SOLO cup.
WARNING: Do not use hot glue when securing components to the SOLO cup! See picture 3 for the effects of hot glue on a plastic cup. It could cost you a lot of time if you accidentally burn through your cup!
Step 14: Connect Mainboard and Mount Speaker
All that's left to do is hookup our female wires to the male headers, secure the speaker to the cup, and then finally rock out to some ill beats!
Using a tweezers or small needle nose pliers, attach the dupont wires to the appropriate male header. Be especially careful of the polarity so you don't short out the circuit. Try not to pull too hard on the wires as they (and the cup) are quite fragile.
Once the mainboard is attached to all the I/Os, all thats left to do is secure the speaker. To do this you could use glue, tape, velcro, or some sort of metal lock. I decided to use tape, since I'll be opening up this cup to show/demo it to others and... its cheap! Roll a small amount of tape onto your finger to spread the adhesive on all sides. Line the bottom of the speaker with tape, and carefully push it against the top of the SOLO cup.
Radical! That's one gnarly SOLO cup speaker. Just one more step left: to party!
Step 15: Go Party!
Finally, you can go hit up all the parties on campus blasting your hipster house music or dope beats in style! Or even listen to music alone and pretend you're partying! Either way, you've got a pretty unique hip SOLO cup speaker. I hope you've learned a bit about audio amplification, stereo/mono audio, schematics, and using the dremel. If you enjoyed this instructable, please support me by voting for this instructable in the University, FormLabs, or Tech Contest! Thank you for your interest in my project!
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