Craft stores are often the source of odd inspiration. In the stained glass section, we’ve seen the copper foil, and even used it to prototype some RF circuits on the tops of shoeboxes. However, we could never get a good method for connecting ICs to the relatively thick foil. [Bryan Cera] did it though. His paperSynth uses some paper and cardboard for a substrate, copper foil, and an ATtiny CPU to make music. You can see the device in operation in the video, below.
The copper foil is sticky and it isn’t conductive on the back, so anywhere the foil is supposed to touch, you need a blob of solder. We wouldn’t trust the insulation by itself to cross wires, but with a bit of insulating material between–a piece of paper or electrical tape, for example–you could probably cross with impunity. For an RF circuit, you might even make low-value capacitors like that.
Even though we’ve used foil before, we got a lot out of reading this project. The battery clip and on/off switch was ingenious. There are five different modes for the synthesizer. Single notes, double notes, triads, four notes, and a drum mode.
If you want something more sonically impressive, like this Teensy-based poly synthesizer we looked at recently, you might have to change to a different construction technique. For a quick project, using copper tape and cardboard can get you going fast and still have a neat appearance. We like it. If you think tape is low tech, by the way, think again.