A position sensitive midi drum pad

Step 2 Tools and Materials

You will need the following materials:

• a 30 cm square sheet of 3mm thick aluminium.
• a 30 cm square of thick plywood (e.g. 10mm) for the base.
• a 30 cm square sheet of thin plywood (e.g. 5 mm) for the top frame.
• a small amount of 10mm closed cell foam rubber (enough to make 8 * 35mm discs). I bought some online, but you could probably use the rubber from something like a camping mat or old style mouse pad. Soft (open cell) foam of the sort you get in cushions probably wouldn't work.
• 8 * 5mm machine screws, around 55 mm long (and matching nuts and washers). If you can, get the kind where the nuts have a plastic insert to stop the nut from loosening.
• 4 * 35mm diameter piezo transducers.
• 4 small metal discs a bit smaller than the inner contact of the piezo. (E.g. 4 one pence coins).
• Some 30 Awg wire (i.e. v. thin) to wire the piezos.
• Some shielded 1 core cable to carry the signal from the piezos to the arduino.
• Contact adhesive which will stick rubber, wood and metal.
• Epoxy adhesive.
• Gaffer tape.
• 4 * 1 MOhm resistors.
• 2 * 10 KOhm resistors.
• 1 * 100 Ohm resistor.
• 1 * TS912 Op-amp.
• 1 * 2N3904 npn transistor.
• A breadboard or piece of stripboard to build the circuit on.
• Solder.
• Miscellaneous jumper wires.
• An arduino board and usb cable. Any of the arduino boards will do - you just need 4 analogue inputs.

• Magic marker for marking the aluminium sheet.

and the following tools:

• Saw to cut the plywood sheets to size.
• Pad saw / fret saw with metal and wood cutting blades. This is for cutting the central hole in the top frame. You only need the metal cutting blade if you need to cut the aluminium sheet to size.
• Electric drill.
• 5 mm wood drill bit.
• 10 mm metal drill bit.
• Large wood drill bit for making the initial hole to use the pad saw through.
• Screwdriver.
• Soldering iron.
• Wire strippers.