Friday, August 28, 2009

The Cheapo keyboard plays itself !

This is just a little idea I've been playing with that you might enjoy. I'm using Lunetta techniques to help bend a toy. First let's get to know the victim:

It's the simplest keyboard I could find, i think i got it for a dollar. The IC is a blobby one, so i focused on learning the basics of keyboard matrices.

Pretty simple, there are groups of buttons, then items within each group.
When you press a key, you're connecting a group and an item and the blobby IC plays it's note.

So how to hack this baby to make it play itself? Here's the plan:

The main job is done by 4052, which is a dual multiplexer. Its big brother 4051 is used quite often in Lunetta machines but I thought I'd give this one a try. This chip can act as a group of analog switches to connect data lines together. Connect four inputs on each side, use logic signals at the A and B pins to select which channels get to the output for each of the two muxes. Connect those two outputs and you're basically rubbing wires together.

And here's what it sounds like. Because I used just a few ICs it's pretty repetitive, so had to turn knobs and change connections to make it do something interesting.

Need to think of better ways to make the 4052's connections have more variety.

Selfplayingcheapo01 by droffset

Instead of using two halves of a 4052 the setup no has an additional 4051 to handle the note selection, while half of the 4052 is still selecting which group of notes to select from.

Selfplayingcheapo02 by droffset
I think i destroyed the circuit, or at least the built in wiring, need to resolder tons of stuff. The bend circuit is more complex than the little crappy thing it's meant for, but the sounds coming out are pretty cool for what it is.

Posted here

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