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Help me build Buchla/Serge style Capacitance Touch Keyboard?
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ericcoleridge



Joined: Jan 16, 2007
Posts: 885
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PostPosted: Tue Jul 22, 2008 8:09 pm    Post subject: Help me build Buchla/Serge style Capacitance Touch Keyboard?
Subject description: Attached: pcb layout for Buchla key pads
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I've been building modules for a portable briefcase and/or fold-up boat for quite a while now--many of the modules inspired by and/or reproduced from Buchla designs. Most all of what I've built is from layouts circulating on this forum. I recently posted some pictures of my first panels, but here they are again, pictured below--to provide more context for this ongoing project.

Anyway, I've always thought the crowing jewel in this set-up could be a capacitance keyboard, or even a touch pad keyboard ala EMS. I have this Touch Controller schematic from Synapse, submitted by Serge, as well as the Programmer schematic, that goes with the Controller, from the next issue. I've also been looking at some of the Bugbrand circuits, like the weivel, etc. These circuits are well described and they seem doable, even for me.

However, maybe the most contentious issue about building a controller like this, for me, would be in designing and constructing/fabricating the actual keyboard.

I've been told that on the early Buchlas, the keyboard was made from an actual PCB, with the keys simply etched onto the conductive metal-- and also that the Serge controllers were/are made from pezio elements.

I've also read that there was a Japanese analog synth circuit book published in the 70s or 80s with many schematics and PCB layouts of commercial synths and included a PCB layout for the Buchla touch controller. This would, of course be a great help if I was to go the etched PCB route. Probably some people here have this book I'm talking about, and I'm just wondering if anyone would be so kind in sharing this layout with me?

Also, though, I guess I should say, my most ideal inspiration for a touch controller would have to be the later Buchla keyboards, such as the 218-219 touch controllers, also pictured below. But, I have no real idea how these are constructed. Most likely they are factory fabricated instruments and perhaps beyond my limited fabrication resources.

But I'm just putting it out there for anyone's musings...Does anyone have any ideas on how a controller like the 218-219 could be made? The physical keyboard, that is? I'd love to know if anyone here has tried to make a controller project like any these mentioned (and how Very Happy).


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Last edited by ericcoleridge on Thu Jul 24, 2008 11:44 am; edited 1 time in total
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crashlander42



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PostPosted: Tue Jul 22, 2008 8:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

I was interested in building one of these as well, but I never had the time to stare at the schematics until they made sense.

http://rubidium.dyndns.org/~magnus/synths/companies/buchla/

(I don't know if you've already looked at these)

If anyone has the PCB layouts, holycrap I'd love to see that.

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Coriolis



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PostPosted: Wed Jul 23, 2008 1:53 am    Post subject: Reply with quote  Mark this post and the followings unread

Yeah, this is something I also want to build at some point.
Having never worked with either piezo's or capacitance-touch plates, I don't know where I would start, but I like the idea of being able to simply etch a pcb with touchplates Bugbrand- style (could get creative with shapes/layout).
That would certainly be doable for me.

Apart from the Synapse articles, there is this article at the paia site as well:

http://www.paia.com/ProdArticles/touchsw.html

Don't know how usable that is for gate-signals though - looks like it only does triggers.

Argh...this kind of thing comes up pretty frequently it seems, and I really want this kind of functionality bad. Unfortunately I'm no EE, and I have so many other modules on my plate before I can get to even thinking of breadboarding/fumbling/kludging/failing miserably with something like this... Rolling Eyes

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a.b.o.z.



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PostPosted: Wed Jul 23, 2008 2:07 am    Post subject: Reply with quote  Mark this post and the followings unread

If one can reproduce something similar to this it would be awesome!!!
I wanted to do something with capacitance switches but never got around to it. I was planing on doig capacitance switch keyboard and then connect it to MFOS 1V/oct keyboard controller. Damn I want more time. Sad

http://electro-music.com/forum/viewtopic.php?highlight=touch&t=20222
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CJ Miller



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PostPosted: Wed Jul 23, 2008 2:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Your panels look great. And those blue knobs... ! You are going to have a lot of fun with those circuits.

I am slowly building some of these same projects, but taking forever - too much on my "plate" for now. I definately intend to build a touch keyboard or several. They are not only switches, but actually pressure sensitive as well, which makes for a more articulate analog keyboard than the typical single-bus mono switch type. As for Serge, I have heard about piezo units but they definately offered many with real capacitive touchplates.

The circuitry for these kinds of things is not too complicated, but repetitive. Certainly check out the Buchla schematics on Magnus' pages. There's some PCB info somewhere, but it'll be tricky to use unless you can make really long boards. Or I'm sure you can break it up into a few smaller chunks. I'm gradually making the Serge keyboard from Synapse, just 12 keys to start with.
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widdly



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PostPosted: Wed Jul 23, 2008 3:19 am    Post subject: Reply with quote  Mark this post and the followings unread

I've never seen or played one of those capacitive keyboards. I wonder how reliable they are.

Force sensing resistors might be worth looking into.
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CJ Miller



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PostPosted: Wed Jul 23, 2008 3:28 am    Post subject: pr0n salad Reply with quote  Mark this post and the followings unread

I haven't seen many good pictures out there of Buchla internals, but here are a few nice photos of a 219 touch keyboard from Paul Schreiber's site:

http://www.synthtech.com/pix/buchla/b219/

Of course he had to cover that bizarre photoelectric joystick, but I would love to see more of the PCB.

I'm attaching a few photos I found (don't remember where) of a Serge TKB board. This is a capacitive touchplate board, different from the one in Synapse. Enjoy... !


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vtl5c3



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PostPosted: Wed Jul 23, 2008 6:41 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

I've got the docs you're looking for. Wink

Starting off with the schematics and parts list:


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vtl5c3



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PostPosted: Wed Jul 23, 2008 6:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Here's the PCB Layout, and parts overlay.


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vtl5c3



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PostPosted: Wed Jul 23, 2008 6:46 am    Post subject: Reply with quote  Mark this post and the followings unread

And it wouldn't be complete if I didn't include the PCB layout for the touch keys, now would it?


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ericcoleridge



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PostPosted: Wed Jul 23, 2008 8:13 am    Post subject: Reply with quote  Mark this post and the followings unread

CJ Miller wrote:

They are not only switches, but actually pressure sensitive as well, which makes for a more articulate analog keyboard than the typical single-bus mono switch type.


The few people I've spoke to who have actually used the Buchla Touch Controller are emphatic about how well it responds, and what an unusually great controller it is. This, the aestetic qualities, and the flat compact design, make it a very appealing package. But, I haven't found much on the internet in the way of DIY appraoches to this design, which is unfortunate.

CJ Miller wrote:

As for Serge, I have heard about piezo units but they definately offered many with real capacitive touchplates.


I've only seen the Serge peizo version, but, in a way, it seems like a peizo would be just as useful, instead of surface area response, it gives you actual pressure response. Not sure which would be better (both would be cool).

CJ Miller wrote:

The circuitry for these kinds of things is not too complicated, but repetitive.


Agreed. I think the original Buchla's had something closer to 12 pads.

CJ Miller wrote:

Certainly check out the Buchla schematics on Magnus' pages. There's some PCB info somewhere, but it'll be tricky to use unless you can make really long boards. Or I'm sure you can break it up into a few smaller chunks.


The Buchla design is pretty close to the Serge/Synapse document, no? You're more/less sending a trigger to a 'programmer,' right?

I figured it wouldn't be too much to adapt this to a switch for a Volt/per octave circuit like Ray Wilson's. I think, at least at first, I'd prefer standard tuning to programmable voltages.

Once, not long ago, a few months ago maybe, while searching for any more info on these controllers, I noticed that Marc Verbos was selling a set of actual Buchla PCBs for the Tocuch Controller on e-bay. It didn't sell for too much, if I remember right...
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numbernone



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PostPosted: Wed Jul 23, 2008 8:15 am    Post subject: Reply with quote  Mark this post and the followings unread

Oh man how I love the look of old hand drawn PCB traces!

I have a Ciat Lonbarde Sidrassi Organ which uses piezos attached to the "keys", it is a very sensitive and expressive interface. I am intending to try and emulate this type of control. I will be watching this thread closely,and will add any discoveries I make.

Funny how it is starting to boil down to everyone realizing that Buchla is really the BEES KNEES.
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ericcoleridge



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PostPosted: Wed Jul 23, 2008 8:43 am    Post subject: Reply with quote  Mark this post and the followings unread

widdly wrote:

Force sensing resistors might be worth looking into.


Yep. Definitely another way to go. Check out this picture from composer James Fei--he's using some standard flexi-sensor types.

I have a free sample of one of these sensors--and it works extremely well--just perfectly.


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ericcoleridge



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PostPosted: Wed Jul 23, 2008 8:49 am    Post subject: Reply with quote  Mark this post and the followings unread

vtl5c3 wrote:
And it wouldn't be complete if I didn't include the PCB layout for the touch keys, now would it?


Thanks. This is what I was after, the keys.

Check out this other image from james fei's website, part of his buchla cabinet:


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Last edited by ericcoleridge on Wed Jul 23, 2008 8:52 am; edited 1 time in total
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fonik



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PostPosted: Wed Jul 23, 2008 8:51 am    Post subject: Re: pr0n salad Reply with quote  Mark this post and the followings unread

CJ Miller wrote:
...different from the one in Synapse. Enjoy... !

so what about the synapse circuit? one would have to add a keyboard scanner cicuit (MFOS?) and that's it?

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ericcoleridge



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PostPosted: Wed Jul 23, 2008 8:57 am    Post subject: Reply with quote  Mark this post and the followings unread

I really like these pictures...


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fonik



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PostPosted: Wed Jul 23, 2008 9:13 am    Post subject: Re: pr0n salad Reply with quote  Mark this post and the followings unread

fonik wrote:
CJ Miller wrote:
...different from the one in Synapse. Enjoy... !

so what about the synapse circuit? one would have to add a keyboard scanner cicuit (MFOS?) and that's it?

uuh, i don't understand it...

the keyboard delivers triggers (and additional pressure voltages, the common would be enough, i think).
what would i have to add to get a chromatic keyboard?

here is the synapse article (cyndustries):
Posted Image, might have been reduced in size. Click Image to view fullscreen.

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ericcoleridge



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PostPosted: Wed Jul 23, 2008 11:37 am    Post subject: Re: pr0n salad Reply with quote  Mark this post and the followings unread

[quote="fonik"]
fonik wrote:

the keyboard delivers triggers (and additional pressure voltages, the common would be enough, i think).
what would i have to add to get a chromatic keyboard?


Couldn't you just use the triggers to (CMOS) switches in place of standard keyboard switch action? Then, as you mentioned, you could just use something like Ray Wilson's volt/oct keyboard circuit.

I'm still wondering what could make really nice, physical key pads though (besides etched PCB).

Fonik, do you think that Schaeffer could produce thin keypads, that could be mounted on a (plastic?) panel? I'm asking because I know you've done alot of your stuff through Shaeffer. I think they do aluminum cut-outs, but I also am not sure how conductive/capacitive the alluminum would be.
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Peake



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PostPosted: Wed Jul 23, 2008 5:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

I had a 217 touch keyboard once and it was notoriously difficult and time-consuming to calibrate (one that I wouldn't attempt myself; gave it to a tech). It seems that each key calibration can interfere with the neighboring calibrations, or something similar. I can't say that I would recommend that circuit. I haven't played one of the smaller ones so I don't know if it's more responsive (the 217 sometimes didn't "see" when you played a key).

I'd certainly be into a remake, if it weren't too non-discrete. Modern component speeds take away from the analog character.
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Blue Hell
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PostPosted: Wed Jul 23, 2008 5:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Maybe this (microchip mTouch sensing solutions) could be an interesting modern day solution for capacitive keyboards?
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vtl5c3



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PostPosted: Wed Jul 23, 2008 6:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey Peake,

You had a 217? How was the touch control strip above the touch keys? I've always wondered if that wouldn't be a good DIY solution for a ribbon controller like device. For those who don't know what I'm talking about, there's a pic and description on Buchla's website:

http://www.buchla.com/historical/b200/217-keyboard.html
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Peake



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PostPosted: Wed Jul 23, 2008 6:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

vtl5c3 wrote:
Hey Peake,

You had a 217? How was the touch control strip above the touch keys? I've always wondered if that wouldn't be a good DIY solution for a ribbon controller like device. For those who don't know what I'm talking about, there's a pic and description on Buchla's website:

http://www.buchla.com/historical/b200/217-keyboard.html


It was excellent; I'd buy a box with two of them alone if it were available. (Edit: Only if they were vintage circuits- none of this modern high-speed stuff, thanks.)

They each output gate, pressure, and position (both increasing toward the center of the unit, IIRC). Because they're nonlinear they're a lot of fun.

Buchla also included a set of four individual keys which output a settable voltage, gate, and pressure (each). Very useful for initiating events or modulation paths.
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toppobrillo



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PostPosted: Wed Jul 23, 2008 8:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Maybe this (microchip mTouch sensing solutions) could be an interesting modern day solution for capacitive keyboards?


or these: http://www.cypress.com/capsense/?id=37

the development software looks easy for a novice [like me] to get into, with alot of time [not like me] there are some examples that might fit the bill as is.. i haven't really looked into it a whole lot. check out PSOC express..
they sell development kits as well, for $89.

here is a good article that details the construction of a control surface and the application of one of these cypress ICs:

http://www.planetanalog.com/features/showArticle.jhtml?articleID=181401898
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ericcoleridge



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PostPosted: Wed Jul 23, 2008 8:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

Peake wrote:
I had a 217 touch keyboard once and it was notoriously difficult and time-consuming to calibrate (one that I wouldn't attempt myself; gave it to a tech). It seems that each key calibration can interfere with the neighboring calibrations, or something similar. I can't say that I would recommend that circuit.


I may be totally off here, but it seems to me that this would be more of a problem with the 'programmer' circuit, as opposed to the actual keypad/trigger circuit. If the Buchla is like the Serge, the keys simply trigger another circuit that is programmed or set to output a specific voltage. Being able to program your scale and key voltages makes the circuit very versatile-- but I'm not surprised to hear that it required much calibration.

I have a Minimoog, which of course has a standard keyboard, and it requires quite a bit of calibration as well to get 'perfect' tuning.

How did you feel about the key response in general? and the 'pressure' output?
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ericcoleridge



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PostPosted: Wed Jul 23, 2008 8:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

topp wrote:
Quote:
Maybe this (microchip mTouch sensing solutions) could be an interesting modern day solution for capacitive keyboards?


or these: http://www.cypress.com/capsense/?id=37


This looks pretty great. But what would you construct the keys from, if not from copper etching, that is? The problem I have with etched copper clad is just aesthetic. It's not always easy (for me anyway) to get super sharp edges when etching, and also obviously the fiberglass (or whatever it is) can look at bit lackluster. Also I'd really like silver keys. I realize this should all be besides the point, an etched board should function--but just for the sake of argument-- any ideas?
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