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geekhack Community => Keyboards => Topic started by: Icarium on Sat, 21 January 2012, 08:37:47

Title: Analogue switches
Post by: Icarium on Sat, 21 January 2012, 08:37:47

Are there any switches one can get analogue signals from? Not sure what I want to do with that information yet but it sounds like fun. :)

Title: Analogue switches
Post by: hazeluff on Sat, 21 January 2012, 09:05:15

Quote from: Icarium;495497

Are there any switches one can get analogue signals from? Not sure what I want to do with that information yet but it sounds like fun. :)

I'm not quite sure what OP is asking for. @_@

Title: Analogue switches
Post by: kps on Sat, 21 January 2012, 09:12:58

Quote from: Icarium;495497

Are there any switches one can get analogue signals from?

MIDI supports both speed and pressure reports from musical keyboards. Without looking, I would guess that they measure speed by timing two or more contact points, and pressure with strain gauges.

If you want position reports, I'd suggest looking for an old industrial keyboard with Hall-effect switches to hack on.

Quote

Not sure what I want to do with that information yet but it sounds like fun. :)

With pressure sensitivity, the keyboard could automatically engage Caps Lock WHEN YOU GET ANGRY.

Title: Analogue switches
Post by: Icarium on Sat, 21 January 2012, 09:20:46

See, great ideas already. :) Hm...hall switches...hm...I'll see if I can find anything.

To clarify, yes the idea was to have pressure or position reported and then use it to speed up repetition, add a bottom-out layer or other stuff like that.

Title: Analogue switches
Post by: woody on Sat, 21 January 2012, 09:42:50

Quote from: Icarium;495497

Are there any switches one can get analogue signals from?

Example: capacitive sensing switches, resistive switches like the ones in PS2/PS3 controllers.

Title: Analogue switches
Post by: kps on Sat, 21 January 2012, 09:46:26

Quote from: Icarium;495523

To clarify, yes the idea was to have pressure or position reported and then use it to speed up repetition, add a bottom-out layer or other stuff like that.

Ah yes. IBM had a nice-looking patent (http://www.google.com/patents/US4274752) on a beam-spring variant for that purpose. I'm not aware of it seeing production. If I had a zillion dollars, that's the switch I'd clone today.

Maybe you could try sandwiching a little piezo buzzer between PCB and keyswitch to detect bottoming-out impact.

Title: Analogue switches
Post by: Icarium on Sat, 21 January 2012, 10:28:45

Between PCB and keyswitch....there shouldn't be any movement between those, should there?

Title: Analogue switches
Post by: kps on Sat, 21 January 2012, 14:19:22

Quote from: Icarium;495559

Between PCB and keyswitch....there shouldn't be any movement between those, should there?

None noticeable, but I suspect it wouldn't matter — they use piezos for acoustic string pickups, sandwiched 'immobile' between the bridge and body, so I'd bet you could measure the bottom-out force by its volume. You probably couldn't use Cherry switches, since they have a big alignment pin in the middle, but rather ALPS or others.

Title: Analogue switches
Post by: Kurk on Sat, 21 January 2012, 19:25:24

These guys are building an isomorphic keyboard that uses modified cherry switches in combination with another layer of switches for velocity sensing. It's explained at ~1:30 in the video:
http://www.youtube.com/watch?v=KfjEYu79J-4
So it's not an analogue signal but still very interesting.

Title: Analogue switches
Post by: Icarium on Sun, 22 January 2012, 01:50:59

Would be interesting to see how that feels. Not what I really want, though. :)

Title: Analogue switches
Post by: woody on Sun, 22 January 2012, 04:29:21

Why would you want velocity sensing? So that you have one more source of mistakes?

Title: Analogue switches
Post by: Kurk on Sun, 22 January 2012, 04:41:25

Quote from: woody;496116

Why would you want velocity sensing? So that you have one more source of mistakes?

Well, it's for making music not for typing.

Title: Analogue switches
Post by: woody on Sun, 22 January 2012, 04:49:38

Ups, sorry. Missed the "isomorphic" part.
Cheap MIDI keyboards use two-point velocity sensing.