[sdiy] Keyboards good for scrap / repurposing?

rsdio at audiobanshee.com rsdio at audiobanshee.com
Sun Feb 18 08:24:24 CET 2018

Most keybeds have a local PCB with the raw electronics for a scanning matrix. That means it will be wired for Rows and Columns, each of a specific bit width, and diodes to prevent ghosting. I assume you’ll want support for Velocity, which simply means twice as many switches (although there are some clever ways to share either Row or Column between the two switches for each key). I’ve never seen a keybed with sound generating electronics on the same board, so you most likely won’t have to rip out anything that you won’t use.

My question is whether your projects will have a CPU, and whether you’ll be programming the firmware. If yes to both, then it should be fairly easy to allocate the appropriate GPIO pins to the Rows and Columns from the keybed and then pick a scan rate and allocate some bits to key state so you know when to generate Note On or Note Off messages, with Timers or something to measure the switch timing for Velocity.

The only other challenge might be finding a connector that matches the connector from the keys. I’m assuming that you’ll make a custom PCB for your project that will include everything but the circuits on the keybed. If that’s true then just plan for a matching connector on your board.

If you’re not using a CPU or writing your own firmware, then maybe something like the MIDIbox or some other MIDI kit could be hacked to connect to the keyboard.

Brian Willoughby
Sound Consulting

p.s. There are the old, non-Velocity designs with J-wire mechanisms. Those could possibly be adapted, but they might be disappointing compared to the more modern standard switch-based keyboards.

On Feb 17, 2018, at 7:28 AM, sleepy_dog at gmx.de wrote:
> Are there some known models of keyboards (MIDI or with sound engine, no matter) which would make sense to look for in "broken" condition to get them cheap, to use the keys for DIY synths? I.e., they should lend themselves well to ripping out the keybed/keys without damaging the needed parts. I guess you'd always have to build new switches PCBs, as such keyboards would have everything (I dont' need) on one PCB, right? (I never opened such a thing)
> I am interested in both, quality, and "usable enough to have some fun" types for different purposes ;-) And it's not restricted to short keybords generally, just right now in particular I'm after a cheap 37..43 key one.
> - Steve

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