I’ve wanted to build a spring instrument for a while after seeing the amazing Electro Faustus Blackfly in action. I stumbled across some videos of Simon the Magpie and his many interpretations and hacks for the Blackfly and felt inspired to create my own version.
This is a very simple build, it requires no power source and very basic soldering skills. You can source all the parts from your local hobby supply or hardware store, or eBay of course.
- Piezo Element – the biggest you can find so that it doesn’t need amplification. I used a 50mm which works well.
- Momentary button (SPST) – this will be used as a kill switch to cut the audio output while the button is pressed.
- Potentiometer (100k) – Controls the output volume.
- Audio out socket – I use a 3.5mm (1/8th inch) mono socket/jack in this example but you can use whatever type of output you like. A standard guitar pedal in/out is 1/4 inch.
- Project box – I’d suggest a metal box to help the Piezo pick up the sound vibrations from the springs. The size will depend on how big the springs are that you want to mount on the lid, again there is no right and wrong here, just whatever suits your needs. The box I used was slightly wider than a typical guitar stomp box.
- Springs – Ensure that they will fit on your project box when they are sightly stretched out.
- Nuts & Bolts – We’ll use these to mount the springs to the projects box.
- Wire – Your average DIY “hobbyist” wire will be fine.
- 1 Knob for the volume pot
- Soldering Iron
- Wire cutters
- Hot glue gun
- Solder the Piezo element, audio jack, potentiometer and momentary button together connecting each element with wire. To make it easier for mounting, make sure your wires are longer than you’ll need. The diagram below shows how the circuit needs to be connected.
2. Mark out the locations where you want the knobs and springs to be mounted on your box. I mounted the springs across the center of the box where the Piezo will be glued so that it picks up the maximum amount of vibration. The easiest way that I found to mark the location of the spring mounts was to sit the spring across the box and mark each end, then drill the holes slightly back toward the edge of the box so that the springs will stretch slightly when mounted.
3. If you want to paint or decorate your project box now is a good time to do it. If you paint the box you may need to sand out the holes you drilled afterwards to remove any additional paint that will cause the pots etc to not fit.
4. Glue the Piezo elect to the inside of the project box lid as close to the center as you can. I used a small amount of hot glue under the edge of the Piezo to attach it to the box then glued right around the outside edge to form a seal. You could also use a strong super glue but you might need to leave it overnight to set whereas hot glue dries almost instantly.
5. Add the mounting bolts to the springs. Add one bolt above and another below the spring and tighten them firmly to hold the spring in space. Do this for each and of the spring and then use the same process for mounting it to the project box lid (1 bolt top and bottom, tighten firmly). I mounted one spring slightly higher than the other to create a slightly different sound, mount your in any way you like.
6. Attach the remaining elements to the box (potentiometer, momentary button and audio jack) and ensure that there is no pressure on any of the wires or solder points when you place the cables inside the box and put the lid on. This will just avoid having to resolder connections later on.
7. Screw down the lid, attach your knob and you’re done! Easy right? Attach your completed spring instrument to your modular or at the start of an effects chain to trigger weird and wonderful sounds. Tap the box with your finger or slide coins and different objects down the springs to create different effects, pluck the springs at different strengths to make harsh noise. These are a great little tool for sound design.