PaperSynth v2 is an "8-bit synth" circuit for creating musical square wave tones - made with paper, copper foil tape, an ATTINY85 microcontroller and some simple electrical components.
Step 1: Bill of Materials
Below is the list, with links, of the required tools, materials and components for creating a PaperSynth circuit.
For building the paperSynth:
1.) Soft Potentiometer 50mm: from Amazon, here.
2.) 8 Ohm Speaker: from Amazon, here.
3.) ATTINY85 Chip: from Digikey, here.
4.) 8-pin IC Socket: from Digikey, here.
5.) Potentiometer: from Amazon, here.
5.) LED strip segment: from Amazon, here.
6.) 220 Ohm Resistor: from Digikey, here.
7.) Pushbutton Switch: from Amazon, here.
8.) Coin Cell Battery x2: from Amazon, here.
9.) 1/8 Inch Copper Foil Tape: From Amazon, here.
9.) 1 Binder clip: From Amazon, here.
10.) Craft Board or Card Stock From Amazon,here.
11.) paperSynth Schematic/Template:See below
12:) Spray Mount: $9.41 from Amazon here.
13.) Super Glue: $5.56 from Amazon, here.
1.) soldering iron and solder
2.) scissors or x-acto knife
3.) small pliers
And if you havent programmed an ATTINY85 before, you might need these:
1.) Arduino Uno Board: $21.00 from Amazon, here.
2.) Breadboard: $4.66 from Amazon, here.
2.) Jumper Cables: $7.50 from Amazon, here.
3.) 10UF Electrolytic Capacitor, $1.05 from Digikey here.
Step 2: Prep Paper Template
Once you've aquired the components and materials, it is time to prep the paper Template!
1.) You can download the printable template for PaperSynth v2 (PDF).
2.) Print it (on any normal printer) at 100% scale.
3.) Using spray mount, mount the template to craft board or card stock. Be sure you spray in a well-ventilated area!
4.) Next, trim with scissors or Xacto knife.
5.) Finally, score the fold lines with a paperclip (as indicated in the image)
This design is meant to accommodate two 3v coin cell batteries, which will be held in place with a blinder clip!
I learned this trick from Jie Qi - master of paper+electronics!
The "paper" part of your PaperSynth is complete - now it is time to move on to creating the copper foil traces!
Step 3: Plotting the Copper Foil Traces
Circuit boards are basically just made up of flat "wires" (called "traces") that route electricity between components. While they are usually made by removing select areas from the surface of a copper clad non-conductive material, we will make ours by sticking strips of copper foil onto paper.
The copper foil I use (and linked to in step 1) is 1/8 inch wide, and has non-conductive adhesive on one side - making it very easy to stick down onto paper!
1.) To create the traces, place copper foil traces along the light grey paths on the template.
2.) Eventually you will cover up a lot of the component footprints, so I've included a nifty diagram (see image) to help guide you through adding components once the template gets obscured!
3.) The copper foil may get a bit wrinkled as you stick it down - you can use a credit card or the back of your thumb nail to burnish it down - making it nice and smooth!
Once the traces are routed, it is time to solder where each separate strip overlaps, to connect them electrically...
Step 4: Soldeing the Joints
The adhesive backing on this copper foil is insulative - meaning it will not conduct between seperate strips of tape. This means we need to solder all of the corners of our overlapping traces!
1.) For each corner, place your iron down, then feed solder right into the intersection between the iron tip and the copper foil corner.
2.) Apply just enough solder to connect the two strips.
3.) Your traces are complete! You might want to double check continuity of each trace with a multimeter (Test the traces to make sure they are connected properly)
Next we will "stuff" our circuit - by prepping and soldering our electrical components.
Step 5: Stuffing the Circuit
Before we begin soldering components, we have a few which we need to slightly modify. It will also help to glue some of the components down to make soldering a bit easier.
For glueing things down, I like to use Krazy brand super glue - because it is fast setting without the need for a catalyst - and comes with a pretty handy little brush applicator.
This makes soldering easier, but also helps hold the components to the board so we're not just relying on solder alone when we use it.
1.) For the IC socket (our ATTINY85 chip will sit in this), I am using the "Squished bug" technique. You'll want to bend the pins on the socket to roughly match the template. We'll do the same for the pushbutton switch.
2.) Before any glueing or soldering, lay the components out on the circuit and make sure you understand where each goes. They are each labeled clearly on the diagram in step 3.
3.) You should not apply the glue to the metal leads on the components - but rather to the plastic housing or non-conductive parts. Otherwise we will experience a pretty noxious smell when we solder...
4.) Take care to align the IC socket before sticking down. The krazy glue will give you a couple of seconds to adjust before it sets completely.
5.) In addition to the IC socket and pushbutton, we need to slightly modify our potentiometer by bending the leads downward 90-ish degrees.
6.) Rather than glueing the resistor, I like to use the SMT strategy for soldering components: lay down a blob of solder, sink one lead of the component into it, then solder the other leads.
7.) The 8-ohm speaker is the last part to glue, because the LED strip and soft pot have their own adhesive backing.
8.) Take care to align the soft pot before sticking. The third lead of the soft pot (at the bottom of the circuit) is not used in this design.
We're almost done! All we need now is our ATTINY85 microcontroller - but first we need to load it with the PaperSynth firmware...
Step 6: Loading the ATTINY85 Firmware
It is time to load the PaperSynth firmware I created onto the ATTINY85 chip. Of course, you could always create your own Arduino sketch and load it on as well. Either way, you'll need to get the code from your computer onto the chip - here's how:
I learned to program an ATTINY using an Arduino Uno as an in-system programmer from a tutorial by High Low Tech.
I discovered the ATTINY85 core that includes the tone library here.
I am going to include my own instructions here, however.
To use an Arduino UNO as an ISP, create the circuit pictured here on a bread board.
***When it comes time to program the chip, you'll need to put a capacitor between reset and ground to keep the UNO from resetting after upload. For now, leave that component out.
1.) Download and unarchive the paperSynth_v2_files.zip.
2.) Then, launch Arduino 1.0.1 (newer versions do not support the tone library.) You can download that here.
3.) Open the Arduino ISP example.
4.) You'll need to make a slight change to the code... find the heartbeat() function and change delay(40); todelay(20);
5.) Before uploading the ArduinoISP code, be sure to select Arduino Uno as your board.
6.) Now that we have transformed our Arduino Uno into an ISP, it is time to load our code and board profile for the ATTINY85 chip...
7.) First, set the paperSynth_v2_files folder as the Sketchbook location in Arduino. Then restart Arduino.
8.) Next, select the paperSynth_V2 sketch from the Sketchbook menu.
9.) And select "Arduino as ISP" from the Programmer menu.
10.) Now we can set our board to ATtiny85. (It should show up as an option after we set the sketchbook directory ealier). Be sure to select "ATtiny85 @ 8MHz (internal oscillator).
11.) ***At this point, add the capacitor between the RESET and GND pins.
12.) Before we upload the paperSynth code to the ATTINY85, we need to burn the bootloader for the 8MHz setup. You only need to do this step once (per chip).
13.) Now it is time to program the tiny! Select "Upload Using Programmer" from the File menu.
14.) You may see this error during the bootloader burn or uploading the sketch. It is okay, you can ignore it! If it says "Done uploading" you should be good to go!
Congratulations! You have Programmed your ATTINY85.
Finally, Insert the ATTINY85 chip into the socket. Be sure to orient the chip so that the little circular "notch" faces upward.
Step 7: Battery
PaperSynth will run fine on a 3v battery. However, if you want it to be a bit louder and a bit brighter, I reccomend 6 volts. Lucky for us, we can create our own 6v battery by stacking two 3v cells!
To keep it tidy, I like to tape them together.
1.) Cut a strip of electrical tape roughly the width of two cells stacked.
2.) Then tape them together around their edges. Simple!
3.) Be sure they are both facing the same way - you should see the positive on one end of the stack and negative on the other.
We now have a DIY 6v coin cell!
Finally, secure the battery with a binder clip.
Our PaperSynth is complete!!
Step 8: Lesson!
Check out this simple video demonstration on using PaperSynth v2.
There are 5 different "modes" you can toggle by pressing the pushbutton:
1.) Single Notes
2.) Double Notes
4.) Four notes
Enjoy, and please post videos of your PaperSynth jam sessions in the comments!