www.megadrum.info

Hey all, not sure if this is the best place for this post,

but I was wondering if it'd be easy to build a velocity sensitive midi keyboard with piezos. I've been wandering the internet in a quest for similar projects and this might be the most similar I've found. However, I don't have much of a clue about electronics, or analog to midi conversion, but I do have a very good disposition.

So I wanted to ask first, whether such a thing is possible and in the reach of a low-skilled dyer,
and second, what basics should I study to understand piezo signal to midi signal conversion,
or are there circuits already for sale that could simplify this part?

Wouldn't like to annoy you with questions, I'll be more than happy with little orientation on what I should study first.

Thanks a lot!

There are many very cheap touch sensitive keyboards available everywhere. What's the point of DIY in this case? Just for pure DIY sake or you want to implement something which is not available in these cheap keyboards?

Sorry, I was trying not to bore anyone with my story, but now that you ask...

I'm very interested in microtonality, specially in 46et (a tuning dividing the octave in 46 tiny notes) and have already built an electric guitar for that tuning. I do have a very nice midi keyboard, but it is piano shaped and that means highly unplayable for 46et. For instance, to play a major third I need to count 15 keys, and that slows it much down. The easiest solution to this would be to buy an isomorphic keyboard, like the Axis 49



But the prize is really out of my range.

On the other hand, piezos seem to make very cheap yet good velocity sensitive keys. Also I'd love to learn something about circuitry applied to midi. Problem is, I don't know even where to look first.

I guess you're gonna tell me I could cannibalize a cheap velocity sensitive midi controller, using it as midi brain (would I just connect the piezos to where the keys once were?) but I'd also like to learn something, which is the main profit out of DIYing.

Did you take into consideration that piesoz are impact and not pressure sensors?

I know, still valid as velocity sensitive keys, and very cheap and easy to use.
But you can suggest alternatives.

Anyway, that is not the step where I'm stuck.

In this case you can just take MegaDrum and use 55 of it's 56 inputs for piezo keys.

That's what I was hoping!

So all I have to do is follow the 56 input template.

Thanks!

So do you have a sound device to fit the bill?

Hey,

not exactly, I have an Arduino though.

Anyway, I've changed the project. As my interest is microtonality, having a piezo per key is just too much, and even piezos being cheap the total amount would be expensive. So in the end I'll be using DIY potentiometers made with graphite (painting with a pencil on a paper, basically) and a guitar string. 5v go through the string, the end of the graphite strip is conected to the analog pins, when you stop the string against the graphite you can measure how much of those 5v get through the graphite. As graphite is resistant, the further from the pin I stop the string the more volts will be lost, thus giving me an analog value than I can later read and translate to midi pitch bend. Then the piezos or any other sensor would give me the "velocity sensitive" values to trigger the note.

Not sure if I made myself clear, but it's much simpler than using 53 analog inputs. By the way, do you know of any good 'n cheap pressure sensors?