Arduino Drum Kit, part 1

Hey everyone, heres a fun project that I've sadly had to halt while my Arduino and time was committed to university work.What I hope to do with this blog is write down some more discussion-based aspects of the development, and then when the thing is done, put up an instruction guide or something similar with design files and whatnot.

The basic plan is this - create an electronic drum brain with an Arduino, where the input is a set of piezo transducers attached to some form of percussive pads, and the output is MIDI messages corresponding to notes. This system will send MIDI messages to a computer, which will in turn play the appropriate drum samples.

Sounds very simple... And quite conveniently, the bulk of it is! And most electronic drum kits Ive come across use very similar methods. In fact, wire up a piezo to a jack plug, plug it into almost electronic drum kit you care to mention, hit it and you'll most likely see it work. So the question you may be asking is 'why do electronic drum kits cost so damn much?' well, the answer quite neatly sums up the limitations of my project. Commercial electtonic drum kits generally have these sorts of features:

1. Nice hardware - racks for the pads to sit on, nice pads made of durable materials, decent piezo sensors, pads with multiple sensors (think ride cymbal pads with bells as well) e.t.c. Made to go on the road!
2. Large amounts of I/O - allows the user to attach a ton of pads.
3. On board samples - increases the specification of the system considerably in terms of memory and storage to hold the samples. Anyone who's worked with digital audio knows - storage and fine quality audio aren't the best of friends.
4. Other digital features - complex interfaces, additional MIDI features, custom patches and sample sets, things that increase flexibility to the user.

In short, these are things that make electronic drumkits nice, self contained instruments that require little external technology for proper operation. For this project - almost none of these things will be included to keep costs as low as possible. But how will it work with no pads, very little I/O and no sound to play?
What this project is intended to be is the very fundamentals of a drum 'brain'. As it happens, most of the features mentioned above are great, but not neccessary. Rather than onboard samples, sounds are sorted on the computer via a drum sampler and VST host (more on that in part 2). Rather than huge I/O options, the limited Arduino analogue inputs will be used. Rather than nice pads, the sensors will be attached to whatever you can tape them to and dont mind hitting! This is a brief overview of the system.

 

Some projected costs, taking the cheapest in each case:

• Arduino - £18
• Piezos - can be found for around 30p each. A set of 6 would therefore be £1.80.
• MIDI cable - around £3.
• MIDI interface (omitted from diagram) - cheapest I've found is around the £20 mark.
• VST host - Free!
• Drum Sampler - Free!
• Materials - going to attempt to make pads from butchered mousepads initially. Picked up three for £1.
• Drum sticks - £4 if you're feeling fancy. Any old pen you have lying about, if not.

This sets a ballpark figure of £47.50 - half the price of the cheapest drum brain I can find! Most of these costs are from a quick check online and I'm sure they could possibly be found cheaper. If you've found these things cheaper, that's great! (and let me know!)
A more detailed breakdown of costs will be included at the end of the project.

I hope to extend this system and add all sorts of usefull bits and bobs. Velocity control would be a particularly useful feature,  which I hope to cover later.
Ill be adding more information about this project over the next few days.
Thanks for reading!