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



Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark

PostPosted: Fri Jul 25, 2008 1:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

Great initiative there, Ole... Cool

C

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okvern



Joined: Feb 05, 2008
Posts: 78
Location: Seattle, Washington
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PostPosted: Fri Jul 25, 2008 1:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

Fellow Builders,

Speaking of the Buchla that I used to work with, here's an incredibly bad photo of our setup. When we had to close the studio down, I understand that the system was the subject of a small bidding war between the Smithsonian and the Stearns Musical Instrument Collection (at the University of Michigan).

Note the four model 112 touchplate keyboards! Also, just for Fonik--there's a model 292 quad lowpass gate in the upper left. It was from a later generation of modules, so it needed its own power supply--that's what's in the duct-taped box beneath it.

I've been missing this machine since 1994. Crying or Very sad

Thanks,

Ole


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Coriolis



Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark

PostPosted: Fri Jul 25, 2008 2:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

Just beautiful!
Well, at least you have had the opportunity to play with a Buchla - I don't even think are any in my country... Crying or Very sad

C

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mono-poly



Joined: Jul 07, 2004
Posts: 935
Location: Rotterdam, Netherlands
Audio files: 2

PostPosted: Sat Jul 26, 2008 2:27 am    Post subject: Reply with quote  Mark this post and the followings unread

European countrys with old Buchla are:

- Sweden
- Belgium
- Netherllands

As far as i know.
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ericcoleridge



Joined: Jan 16, 2007
Posts: 885
Location: NYC

PostPosted: Sat Jul 26, 2008 2:38 am    Post subject: Reply with quote  Mark this post and the followings unread

Check this out; Posted on matrixsynth: this guy is building synth modules with cut cardboard enclosures, and most interesting, control surfaces from "special conductive paint"!

This is the control surface I've been looking for; I'm imagining a plastic Shaeffer panel, with key sized etchings that could be filled in with this silver conductive paint. This would be so freakin cool!

http://noisedesign.blogspot.com/

http://www.youtube.com/watch?v=kYAyX5DWkdo

http://youtube.com/watch?v=9wU7DUODM5Q


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fonik



Joined: Jun 07, 2006
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PostPosted: Mon Jul 28, 2008 9:28 am    Post subject: Reply with quote  Mark this post and the followings unread

actually off topic, but:

what about using analog switch ICs (like the MAX323). the switch is on whenever logic in is at 0V. so couldn't i just selt the logic low by grounding it's input with my finger?
these switches could then control a diode matrix which has to be scanned...

such a keyboard would not provide any touch sensivity but it would be still nice for playing glissandos.

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ericcoleridge



Joined: Jan 16, 2007
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PostPosted: Mon Jul 28, 2008 11:29 am    Post subject: Reply with quote  Mark this post and the followings unread

fonik wrote:
actually off topic, but:

what about using analog switch ICs (like the MAX323). the switch is on whenever logic in is at 0V. so couldn't i just selt the logic low by grounding it's input with my finger?
these switches could then control a diode matrix which has to be scanned...

such a keyboard would not provide any touch sensivity but it would be still nice for playing glissandos.


Don't you like the Synapse circuit? Or is it not suited for what you want?
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fonik



Joined: Jun 07, 2006
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Location: Germany
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PostPosted: Mon Jul 28, 2008 11:54 am    Post subject: Reply with quote  Mark this post and the followings unread

ericcoleridge wrote:
Don't you like the Synapse circuit? Or is it not suited for what you want?

Laughing
you are right. i should try the synapse circuit. OTH thiese would require a lot of parts. that alone would not be that bad, but i have a lot of other projects still going on. so i thought the CMOS diode matrix scanner circuit would be easy and fast to build...?

i don't know. it was just an idea. when i have finished the most urgent open projects (vocal filter and PSU/MIDI for the klee2) i will probably give the synapse circuit a go...

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widdly



Joined: Jun 25, 2007
Posts: 265
Location: singapore
G2 patch files: 2

PostPosted: Mon Jul 28, 2008 6:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

If you don't need the pressure output, Mr Clack published a very simple touch switch here... http://electro-music.com/forum/topic-24011.html

I haven't tried it but it does look very simple.

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CJ Miller



Joined: Jan 07, 2007
Posts: 371
Location: 127.0.0.1

PostPosted: Wed Jul 30, 2008 6:33 am    Post subject: Reply with quote  Mark this post and the followings unread

I just got home from work a couple of hours ago, and am busy at building my 12-pad Synapse-style Serge keyboard. It is getting close to being done! Can't find those 430pF timing caps I bought a few weeks ago... Soon though, maybe I can have it all connected, cleaned, and dryed by the weekend so I can test it out. I am sure it'll be fun.

I do also want to check out the more complex Serge keyboard and the Buchlas in more detail later. Maybe once I finally make a few of my own PCBs. Even laying out a Buchla keyboard on (a very large piece of!) perfboard doesn't look to hard if one thinks strategy ahead of time. There are a lot of possibilities here to explore.

I'll get a little more done now before I've got to get to sleep
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fonik



Joined: Jun 07, 2006
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PostPosted: Wed Jul 30, 2008 6:52 am    Post subject: Reply with quote  Mark this post and the followings unread

i am curious how important the shape of the keypads amy be? do you plan to test several shapes then?
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CJ Miller



Joined: Jan 07, 2007
Posts: 371
Location: 127.0.0.1

PostPosted: Wed Jul 30, 2008 7:49 am    Post subject: Reply with quote  Mark this post and the followings unread

fonik wrote:
i am curious how important the shape of the keypads amy be? do you plan to test several shapes then?


Still awake!

The shape supposedly isn't too crucial. I doubt if many have been tried though, I have seen only circles, ovals, squares, and rectangles of various sorts. Photos of Serge pads seem to indicate that they are only circular pads which are separate from a large ground plane. So there's a small solder pad which comes off of the touch plate for affixing a wire behind it, and a single ground connection for the rest of it.

The Buchla keyboards appear to use several rectilinear patterns. I have seen keys which are nested "U" shaped figures, perhaps alternating signal and ground. As I recall now, pictures of the Music Easel had shown touch plates in the shape of miniature piano-like keys. Here are some pics.

I like how Buchla expanded the idea with more touch button surfaces and psuedo ribbon controllers. I don't know anything about RF electronics but it appears that there is a lot we can try here.


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ericcoleridge



Joined: Jan 16, 2007
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PostPosted: Wed Jul 30, 2008 7:52 am    Post subject: Reply with quote  Mark this post and the followings unread

fonik wrote:
i am curious how important the shape of the keypads amy be? do you plan to test several shapes then?


Blue Hell posted a link to this open source, capacitance-touch sensing application, microchip mTouch sensing solutions

Although much of what is there is beyond my understanding, there's a document there called Layout and Physical Design Guidelines for Capacitive Sensing, that describes design issues like pad size and spacing.
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Coriolis



Joined: Apr 11, 2005
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Location: Stilling, Denmark

PostPosted: Wed Jul 30, 2008 12:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

CJ - it's very exciting that you are trying out the Synapse circuits, do keep us posted... Very Happy

C

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dar303



Joined: Jul 15, 2007
Posts: 97
Location: Sweden

PostPosted: Sun Aug 03, 2008 12:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

I would recommend the Serge TKB circuit for anyone that wants to build a complex touchcontroller with good feel and easy interfacing to sequencers or other logic circuits. Is should be available somewhere on the net, I found it over 10 years ago!
It is constructed of quite common CMOS chips with only one TTL chip (74150 if I remember correctly) that needs to be the exact type used in the schematic to get the touch sense to work.

The Buchla 221 is a beast, I actually have one in my pile of stuff to fix but it is a very big and scary project! Smile
I managed to repair another one about a year ago but it was hard. The schematic (wich I cannot share, sorry!) is hand drawn by Don across several pages. It has very complex logic due to the fact that is was meant to be a programming interface for the 300 system.
It has several fun features like generating a control voltage from a lamp and a photocell when the front panel flexes from you finger pressure, four preset voltages with pots activated when you touch the pads to the upper right.
The
PCB touch plates looks tin plated and are protected with a layer of laquer and are separated by thin strips of aluminium that sits in pockets in the pcb.
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fonik



Joined: Jun 07, 2006
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PostPosted: Sun Aug 03, 2008 11:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

CJ Miller wrote:
I just got home from work a couple of hours ago, and am busy at building my 12-pad Synapse-style Serge keyboard. It is getting close to being done!

how did you connect the trigger out of the keyboard to the programmers input?

the programmer article states that "...the pushbutton may be replaced by hardwiring their lead connections to the pulse outputs of the Touch Sensitive Keyboard...".

would that mean to connect the trigger of the TSK to both sides of the diode of the programmer instead of a switch??? i don't get it.
the 470pF cap, the diode and the 47k resistor of the external pulse in can be omitted then, right?

why not just leave off the whole pushbutton circuitry of the programmer (including common pulse) and summing the triggers with diodes? the keyboard trigger could get connected to the external trigger in, then.

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Coriolis



Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark

PostPosted: Mon Aug 04, 2008 1:53 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
I would recommend the Serge TKB circuit for anyone that wants to build a complex touchcontroller with good feel


I have those schems you are referring to.
The Synapse article (touch switch) hints at the production TKB having piezo-elements instead of capacitive plates - so are those actually piezos in that schem?

I'm not sure I should post the schem for reference...

C

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dar303



Joined: Jul 15, 2007
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PostPosted: Mon Aug 04, 2008 3:39 am    Post subject: Reply with quote  Mark this post and the followings unread

There are no piezos in there, the scanning is built around a TTL multiplexer.
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CJ Miller



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PostPosted: Mon Aug 04, 2008 5:22 am    Post subject: Reply with quote  Mark this post and the followings unread

fonik wrote:
how did you connect the trigger out of the keyboard to the programmers input?

the programmer article states that "...the pushbutton may be replaced by hardwiring their lead connections to the pulse outputs of the Touch Sensitive Keyboard...".

would that mean to connect the trigger of the TSK to both sides of the diode of the programmer instead of a switch??? i don't get it.
the 470pF cap, the diode and the 47k resistor of the external pulse in can be omitted then, right?

why not just leave off the whole pushbutton circuitry of the programmer (including common pulse) and summing the triggers with diodes? the keyboard trigger could get connected to the external trigger in, then.


I haven't made a programmer yet. I have been thinking about making one for my portable system, but haven't decided how many rows or columns yet.

The Synapse keyboard has no piezo elements, it is purely capacitative. Without the programmer, it is nothing more than a generalized touch interface. A way to get triggers, gates, and voltages from a simple touch controller. Like any module, I can wire it into a programmer, step sequencer, or indeed anything else. As for replacing programmer pushbuttons, one could easily just connect a transistor, CMOS, or analog switch.

I don't really have any grand scheme for how to use this, my system is very basic at this stage. It's just a project that I have always wanted to play with. Years ago I did make a monophonic keyboard circuit, but the only keynoard I had was of poor quality, so the contacts always bent out of shape. What I have really wanted is a polyphonic keyboard that was tunable, and could output a voltage directly, based on some expressive gesture. This keyboard qualifies as such. The Buchla concepts are a bit more sophisticated, as they can also offer a regular voltage step per key, not unlike a bus keyboard, while still offering these other features.

Of my three day weekend, I spent about 60% of it sleeping, which is unusual for me. The insomnia caught up. So I am awake now for another 10 hours before I am due at work, and will try to get a few things done.
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buchlajoe



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Location: new york

PostPosted: Mon Aug 04, 2008 5:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi.
i have this and i dont use it with my system .... i would be happy to photograph any part of it for you to help out with your project.
this is the 216 keyboard made for the CBS performance system.


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mono-poly



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PostPosted: Tue Aug 05, 2008 2:21 am    Post subject: Reply with quote  Mark this post and the followings unread

I love to use it with my system Smile
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CJ Miller



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PostPosted: Tue Aug 05, 2008 3:10 am    Post subject: Reply with quote  Mark this post and the followings unread

buchlajoe wrote:
hi.
i have this and i dont use it with my system .... i would be happy to photograph any part of it for you to help out with your project.
this is the 216 keyboard made for the CBS performance system.


Wow, it's beautiful! And in great condition. Of course, any more photos would be more tham welcome!
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buchlajoe



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PostPosted: Tue Aug 05, 2008 12:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

here is a more detailed pic. let me know if you need something specific.


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scriptstyle



Joined: Jan 22, 2008
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Location: nj

PostPosted: Thu Mar 05, 2009 10:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

I am currently in the middle breadboarding the touch responsive keyboard from the synapse article. What transistors did you guys use? im thinking i can just use 2n3904's?
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andrewF



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PostPosted: Fri Mar 06, 2009 8:27 am    Post subject: Reply with quote  Mark this post and the followings unread

should be fine
I tried it with C1815 which is about as general purpose as it gets
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