MaKey MaKey Scratch Trombone

Building an instrument from upcycled materials and programming it in Scratch

As Maker-In-Residence at the Westport Library MakerSpace I was afforded the opportunity to experiment with many different instrument building techniques. I helped people young and old build musical instruments from cardboard, copper tape with conductive adhesive, aluminum foil, wire, and other upcycled materials. The instruments were connected to laptop computers with a MaKey MaKey and were programmed to make sounds in Scratch.

I built an instrument inspired by Andrew Carle, who suggested the idea of copper tape pads with wire soldered to them as a means of constructing a trombone that worked as a real trombone would, with a slide.

The Slide and Body 

The "switch" that makes this trombone work was inspired by Andrew Carle's design that uses a wire with its insulation removed sandwiched by two pieces of copper tape with conductive adhesive.

The trombone is composed of two parts: a slide and a body. The slide attaches to the body by sliding onto a smaller cardboard tube that is part of the body.

The slide acts as the ground, or Earth, while the copper tape and wire pads on the body connect to the MaKey MaKey's "keys."

A cardboard tube with a small shim attached to one end.
The smaller cardboard tube fit perfectly inside a slightly larger tube. These tubes form part of the body of the trombone.
The cardboard tubes that make up the slide and the body were connected with cardboard from a wire shirt hanger.
Small holes were drilled in the tubes for the cardboard connectors.
The assembled slide. A small strip of cardboard at the end of the tubes connected the two cardboard tubes and provided the curve found on a real trombone slide.
The assembled body. Note the smaller tube coming out of the larger tube at the lower right of the photo.
The ground. The slide contained a long piece of wire with the insulation removed from each end. The wire was sandwiched between two pieces of copper tape with conductive adhesive at the rim of one of the tubes in the slide.
The wire was routed up one tube of the slide and down the other tube.
The wire emerges from the second slide tube. The insulation was removed where it came in contact with two pads of copper tape. The pads are separated by a short gap. The musician can bridge the gap with her or his hand to determine whether the trombone is playing or resting during a song.
Body and slide attached.

The Copper Tape Pads

A series of copper tape pads were built on the smaller cardboard tube on the trombone's body. 

After one set of pads was built, holes were punched in each pad so wires could be routed through the pad. The wires were soldered to the copper tape pads.

Afterwards, the soldered wires were sandwiched between the first pad and a second copper tape pad placed atop the first.

Each pad of copper tape was connected to the next with masking tape. This evened out the diameter of the tube and insured that the copper tape would not get snagged or torn.
There are eight pads so an entire scale can be played.
Each copper tape pad was punctured with an awl. Wire was inserted through each hole and routed down the length of the tube and through the trombone body. The insulation is removed from the end of each wire where it contacts the copper tape.
The wires route from one tube at the rear of the trombone body and back into the lower tube.
The wires emerge from the lower tube of the trombone body. It is vital to label the wires in the sequence they are attached to the copper tape pads.
The wires are soldered to the copper tape pads on the trombone body. Please excuse the amateur soldering job.
Each copper tape pad and wire was covered with another piece of copper tape. Masking tape evened out the height difference to prevent snagging or tearing the copper tape pads.
Body and slide assembled.
Body and slide detail. The wires in the body connect to the up and down arrow keys on the MaKey MaKey as well as W A S D F G on the back of the MaKey MaKey. The blue wire on the slide, at the right of the image above, connects to Earth, or ground, on the MaKey MaKey.
The MaKey MaKey is zip-tied to the body of the trombone. The wires are attached to the MaKey MaKey with alligator clip wires. Most of the wires from the copper tape pads are connected directly to the jumper block on the back of the MaKey MaKey. The labels identify the correct order of the wires.


The trombone is connected to a computer with the MaKey MaKey. The trombone is programmed in Scratch to play notes.

A disclaimer: I do not play the trombone in real life, so instead of the actual slide positions required to play the note that corresponds to its place in the scale, I just placed the notes in succession along the trombone's body. When the slide is all the way in and the ground is bridged, the trombone plays its highest note. 

You can remix the trombone project on the Scratch website.

The Scratch project.
A short clip of the trombone in action.
Short song.

Twitter: @joshburker


This work and images copyright 2015 Josh Burker