The Weevil (No String Guitar)

Introduction: The Weevil (No String Guitar)

About: I am a 15-year-old DIY hobbyist. I mainly focus on electronics, but I dabble in other areas as well. (If you noticed my profile picture I also am a crypto enthusiast)

Have you ever wanted to make music but do not have the money, or don't want to go through the process of learning a new instrument? I have a wonderful solution: the Weevil. In case you were wondering, a weevil is a type of beetle (My favorite band is the Beatles.) The Weevil is a device that is similar to a guitar in nature. It has a guitar-ish shape, you can change notes and pitches, etc. This instrument, however, is cheap and requires little-to-no previous musical experience to play. Let's begin building!

Step 1: Material List


-4 Wooden Rectangles (7.75" x 4.75")

-2 Wooden Rectangles (8.75" x 2.75")

-1 Wooden Rectangle (about 25" x 2.5", but you can adjust the length and width according to preference)

- Speaker (I salvaged mine from a circa 1980 house built-in, because I'm broke. Note: A piezo speaker will not sound good!)- Amazon

- Arduino Uno (Or other Arduino; the steps should be about the same)- Amazon

-HC SR04 Ultrasonic Sensor- Amazon

-Some Jumper Wires- Amazon

-Toggle Switch- Amazon

-9v Battery- Amazon

-9v Battery Clip for Arduino- Amazon

The links above are the best deal I could find. I do not receive any money for putting these on here.


-Soldering Iron

-Hot Glue Gun

-Jigsaw (To cut the wood)


Step 2: Step 2: the Body

The containment of a project is always the hardest part for me, but this "guitar's" body is actually quite simple. First hot glue 5 of the 6 pieces together as shown above. Next glue the neck onto the rest, just like the picture. Save that opening for later so we can but the arduino and other stuff in there.

Step 3: The Electronics

Let's get down to the nitty-gritty. First, cut the red wire of the 9v clip. Now put the switch in between the two red wires. Then solder a black wire to the negative connection and a red wire to the positive connection of the speaker. Next, hook the black wire from the speaker up to the GND connection (the one beside the 5v pin) of the Arduino. Then connect the red wire to pin 8, as shown above. Now it's time for the ultrasonic sensor. Attach the GND pin to a black jumper wire and connect the wire to the other GND connection on the Arduino. Then connect the VCC pin to the 5v pin via red jumper cable. Next, using a wire, hook the TRIG up to the 12 pin and the ECHO peg to pin 11. You are now done with the wiring!

Step 4: Programming

The programming for this project is pretty simple. The code below is for the Arduino IDE. If you are not familiar with the IDE, there is a great Instructable I recommend ( Here's the code: GitHub

*Note: The multiplication symbol (*) and the number being multiplied (2) in line 21 is interchangeable. If you want to change the tonal range of the instrument, try experimenting with different numbers and operations.

Step 5: Putting It All Together

This step is simple. Just stick all the circuitry, not including the speaker, in the body of the guitar*. Now, remember that extra piece of wood that we cut out earlier? No it's time to drill a big hole into it. The size of the hole will vary with the diameter of your speaker. Once all of that is taken car of, you can carefully hot glue the edge of the speaker to the hole like the picture. Next glue down the ultrasonic sensor to the bottom of the neck as shown. Then, you guessed it, hot glue the piece of wood to the opening in the box, as shown above. Before you do this, drill a hole in the top of said piece of wood to stick the ultrasonic sensor cables through.

*Note: make sure no wiring is exposed. If any metal is touching, the circuit will not work. Use electrical tape to make sure no wires are exposed!

Step 6: Make It Look Pretty and Test It.

For this step, I wrapped cool duck tape around the neck. Now you can enjoy playing your Weevil! Also, check out this completely unrelated story that I found on the internet about duck tape: (:

*PS: The wires sticking out of the side of the Weevil are for connection to a sub woofer. The woofer adds some extra depth into the sound.

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    3 years ago

    Interesting, thanks for sharing :)