Bare Conductive › Starter › Article 4

Your First Touch Interaction

Connect physical electrodes to the Touch Board and trigger your first sound without writing any code.

⏱ 20 min read electrodes first project no code crocodile clips sound

What we’re making

A set of six touch pads — pieces of conductive foil or painted areas — each playing a different sound when touched. No code involved.

What you need

  • Touch Board with SD card loaded
  • 6 × crocodile clip cables
  • 6 pieces of aluminium foil (about 5cm × 5cm each), OR
  • Electric Paint and a brush/syringe
  • Paper or card to paint on
  • Headphones or speakers
  • 6 MP3 sound files named TRACK000.mp3 through TRACK005.mp3

Step 1: Prepare your sounds

Find or record six short sound files. Some ideas:

  • Six musical notes of a scale (C, D, E, F, G, A)
  • Six animal sounds
  • Six spoken words
  • Six drum hits

Rename them exactly: TRACK000.mp3, TRACK001.mp3, …, TRACK005.mp3. Load them to the SD card and insert the card into the Touch Board.

Free sound sources:

  • freesound.org — Creative Commons licensed sounds
  • GarageBand — export individual notes
  • Your phone’s voice recorder — record yourself, export as MP3

Step 2: Make your touch pads

Option A: Aluminium foil pads

Tear six pieces of foil (or cut with scissors) and place them on a sheet of paper or card. They don’t need to be neat — any conductive surface works. You can draw or label them on the paper before placing the foil.

Option B: Electric Paint

Paint six blobs or shapes on card, roughly 3–4 cm across. Let them dry completely (20–30 minutes at room temperature, or use a hairdryer on low heat for 5 minutes). The paint should feel dry to the touch and appear a uniform grey/black.

Step 3: Connect the crocodile clips

  1. Clip one end of a cable to electrode E0 on the Touch Board (the labelled pads along the lower edge)
  2. Clip the other end to your first touch pad (foil or paint blob)
  3. Repeat for E1 → pad 2, E2 → pad 3, and so on through E5

The Touch Board’s electrode pads are narrow — clip onto the edge of the pad, not across adjacent pads.

Step 4: Power up and test

  1. Connect the Touch Board to USB power
  2. Wait 2 seconds for the boot sequence
  3. Put headphones on or connect speakers
  4. Touch each pad with a finger

Each pad should play the corresponding MP3 file.

What’s happening when you touch

The default firmware (Intertface) does the following:

  • Reads the MPR121 sensor every few milliseconds
  • When it detects a new touch (a pad that was untouched is now touched), it tells the VS1053 MP3 decoder to play the corresponding file
  • The audio plays through the 3.5mm jack
  • When you release and re-touch, the sound plays again from the start

Simultaneous touches

The Touch Board in default mode can handle multiple simultaneous touches. Touch two pads at once — you’ll hear both sounds play together. The VS1053 chip supports polyphonic playback.

Making it look intentional

Once you’ve confirmed everything works, you can make it look like a proper interactive piece:

  1. Draw or print labels on the paper before attaching the foil
  2. Use Electric Paint to paint shapes that match the sound (a piano key, a drum, an animal shape)
  3. Run painted lines from the shapes to the edges of the paper, then clip to those line-ends rather than the shapes directly
  4. Mount the paper on card or foam board for stability
  5. Tape the Touch Board behind the board with the electrode pads accessible at the edge

Troubleshooting

A pad doesn’t respond:

  • Check the crocodile clip is firmly connected at both ends
  • Ensure the SD card has the corresponding file (e.g., TRACK002.mp3 for E2)
  • Verify the file format is correct (MP3, no special characters in name)

False triggers (triggering without touch):

  • The electrode may be picking up ambient electrical noise
  • Increase distance between electrode cables; they can cross-talk if tightly bundled
  • See article 10 (Troubleshooting) for systematic debugging

No sound at all:

  • Is the SD card inserted firmly?
  • Is the volume up on your headphones / speaker?
  • Is the board powered (PWR LED lit)?

Key takeaways

  • The Touch Board works without any code — just load MP3 files named TRACK000.mp3 to TRACK011.mp3
  • Crocodile clips are the easiest way to connect electrodes for prototyping
  • Any conductive material works as a touch pad: foil, paint, wire, metal objects
  • Simultaneous touches are supported — multiple sounds play at once
  • Test each electrode individually before assembling a finished piece