Giving an acoustic piano electric capabilites

[Ainsley Harriot]

I was thinking about giving an acoustic piano electric capabilities and decided to do it I was thinking about replacing the sheet of wool that hangs from the practice pedal with a piece of wood and putting some sort of sensitivity switch in front of each individual hammer and connecting them to a cheap raspberry pi. Money is important in this equation and I was wondering what would be a good cheap switch that had good enough sensitivity quality for the sound to vary depending on how hard I hit the notes or would there be a cheaper alternative. The reason I’m doing this is because I absolutely despise the way the piano sounds with the practice pedal down yet I usually stay up late and for some reason that's when I want to play but neighbours Please show me some good switches that I could get to work with the raspberry pi it would help a lot.

view attachments for insight on my piano

 

[KrisBlueNZ]

Hi there and welcome to Electronics Point

That's an interesting idea but I really doubt you could do it for less than the cost of a velocity-sensitive MIDI keyboard. Probably not for less than two or three times the cost.

The cheapest way to detect velocity is by having two contacts, one of which makes contact first, and timing the interval between closures using a microcontroller. The harder the key is hit, the closer together the closures will be. That works pretty well when the contacts are underneath the key, but it would be a lot harder to do when your sensor is being hit by a hammer.

You might be able to use a MEMS pressure sensor or a force sensor and detect the peak pressure or force, but these aren't cheap enough. A piezo sensor might work but again, with 88 of them, they're out of your price range, and that's before you even start on the signal conditioning circuitry.

So I think you'd be better to save up for a weighted, velocity-sensitive MIDI keyboard.

 

[Ainsley Harriot]

Hi there and welcome to Electronics Point

That's an interesting idea but I really doubt you could do it for less than the cost of a velocity-sensitive MIDI keyboard. Probably not for less than two or three times the cost.

The cheapest way to detect velocity is by having two contacts, one of which makes contact first, and timing the interval between closures using a microcontroller. The harder the key is hit, the closer together the closures will be. That works pretty well when the contacts are underneath the key, but it would be a lot harder to do when your sensor is being hit by a hammer.

You might be able to use a MEMS pressure sensor or a force sensor and detect the peak pressure or force, but these aren't cheap enough. A piezo sensor might work but again, with 88 of them, they're out of your price range, and that's before you even start on the signal conditioning circuitry.

So I think you'd be better to save up for a weighted, velocity-sensitive MIDI keyboard.

Hi, thanks for the reply, how much would these piezo sensors be I did say I would get as cheap as possible but I want to integrate it with the piano, also I may well be able to put the sensors underneath the keys as long as it doesn't change the feel too much.

edit:

would this work it is extremely cheap http://www.codetinkerhack.com/2013/01/how-to-add-velocity-aftertouch-midi.html

 

[KrisBlueNZ]

You might be able to use piezo "benders" - see http://www.digikey.com/product-detail/en/7BB-12-9/490-7709-ND/4358149 at about USD 0.30 each. These will generate a short high-voltage pulse when whacked by the hammer, but they may not be very consistent and they might get damaged. Also they're pretty big. You could try double-sided foam tape behind one, and on the front as well, to improve repeatability. You would need quite a bit of circuitry to enable a microcontroller to detect and measure the pulse, duplicated 88 times! As I said, not economical.

If you can get access under the keys themselves, you might be able to put the keyboard circuit board from a MIDI keyboard in such a way that the contacts are activated by the keys. That sounds like a lot of hassle too.

 

[Ainsley Harriot]

sorry I mean this, I think I could definitely do it http://www.codetinkerhack.com/2012/11/how-to-turn-piano-toy-into-midi.html

actually I might try and build a matrix myself with push buttons it will be a little new for me seeing as I am a whole lot better with software. and then I'll put an fsr on it, then I'll code it in python to some keyboard program on the raspberry pi. Its close to a tv and I have a spare computer keyboard so I could probably put in some synthesizers when I want to play a particular song. This way it will be more stable then piezo sensors plus i enjoy the task especially when I'm new to this

 

[KrisBlueNZ]

OK, good luck with that!