electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
Live streaming at radio.electro-music.com

  host / artist show at your time
  mosc Back on the air tonight - Twyndyllyngs
Please visit the chat
 Forum index » DIY Hardware and Software » PAIA Equipment
Paia two-note ribbon controller
Post new topic   Reply to topic
Page 1 of 1 [11 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
MirlitronOne



Joined: Nov 07, 2009
Posts: 77
Location: Surrey, UK
Audio files: 2

PostPosted: Tue Jan 03, 2012 12:50 pm    Post subject: Paia two-note ribbon controller Reply with quote  Mark this post and the followings unread

I'm sure that this question should have been asked elsewhere, but I've searched and can't find anything relevant. The question is:

"Has anyone ever successfully built John Simonton's two-note ribbon controller circuit, shown at http://www.paia.com/ProdArticles/dual-ribbon-howto.htm?"

The reason I ask, naturally, is that I have spent the last week laying the circuit out on stripboard and everything works except for the follow-and-hold circuitry. The 'hi' note generator derivation circuitry works fine as does the trigger generator. If isolated, the follow-and-hold circuits work fine. If I unplug the 4066 chip, I can set and hold both ribbon voltages using wire bridges; however, when the chip is in place, both high and low outputs drop to zero as soon as the finger is removed and the gate signal switches off. Same when the 'hold' switches are used (I've used ordinary toggles for hold rather than the touch plate approach).

I've tried two 4066 chips and a 4016 - same results every time. Oh, and I'm using a Spectrasymbol linear sensor for the ribbon.

My tests indicate that the control voltages for the 4066 switches are way out - the control inputs are biassed slightly negative of zero to ensure a clean trigger and when the gate operates, the voltage at the control inputs only rises to about 1 V. However, the switches open fine - it's just that they leak as soon as the gate signal disappears.

All suggestions gratefully received! scratch scratch scratch


[Incidentally, did Paia ever sell a kit for this circuit?]

_________________
Life is like an analogue sequencer. Twiddle the knobs to avoid boredom.
Back to top
View user's profile Send private message Visit poster's website
MirlitronOne



Joined: Nov 07, 2009
Posts: 77
Location: Surrey, UK
Audio files: 2

PostPosted: Tue Jan 03, 2012 3:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

Okay, update - slight impedance issue overcome. The voltages controlling the switch control inputs on the 4066 are actually operating between -0.7 V (off state) and +5.8 V (on state), which, although short of VDD, should be okay for switching states.

The only remaining explanation is one of timing - I guess the 'Lo' and 'Hi' voltages are dropping faster on releasing the ribbon than the 4066 can isolate the follow-and-hold circuitry, so next task is to examine the capacitor values more critically.

_________________
Life is like an analogue sequencer. Twiddle the knobs to avoid boredom.
Back to top
View user's profile Send private message Visit poster's website
TheLoneRoger



Joined: Dec 14, 2008
Posts: 3
Location: Wales, UK

PostPosted: Thu Feb 23, 2012 11:16 am    Post subject: Reply with quote  Mark this post and the followings unread

How are you getting along with this?
It's been on my project to-do list for several years, and now I'm finally about to make a start on it, so any tips or info I can get will be greatly appreciated (don't suppose you drew a stripboard layout...?).

I contacted Paia some time ago, and sadly the project's author John Simonton died of cancer before it got as far as being a commercial project, and they said they thought it unlikely that they ever would be.

Where did you get your ribbon, btw? I have an old piece of anti-static bag i was going to use, but it's looking a bit ragged now...
Back to top
View user's profile Send private message
MirlitronOne



Joined: Nov 07, 2009
Posts: 77
Location: Surrey, UK
Audio files: 2

PostPosted: Fri Feb 24, 2012 5:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well, you got a reply from Paia - they ignored my enquiry.

I gave up temporarily in frustration and haven't revisited it since. Suffice to say that the published circuit doesn't work. I fixed a few problems, but every time I fixed one another appeared! I now have a unit that triggers and sweeps up perfectly, but any downward glissando just drifts down far too slowly, and I still haven't found the reason. If I get it to work I'll post the stripboard layout, modifications and notes, but not until then - it would just mislead people into wasting time and effort on it. I may just give up and design something from scratch.

The strip I'm using is a 300 mm 'Spectrasymbol' linear position sensor from CPC Farnell. They're expensive - nearly £30 each - but I get a discount through work. There are shorter ones.

_________________
Life is like an analogue sequencer. Twiddle the knobs to avoid boredom.
Back to top
View user's profile Send private message Visit poster's website
TheLoneRoger



Joined: Dec 14, 2008
Posts: 3
Location: Wales, UK

PostPosted: Sat Feb 25, 2012 11:30 am    Post subject: Reply with quote  Mark this post and the followings unread

OK, thanks for your reply. I'll see how I get on...

We also have a CPC account where I work, but the search engine on their site is useless and is not turning up anything under 'Spectrasymbol','hotpot' 'position sensor' etc. etc. Do you have a part no.?
Back to top
View user's profile Send private message
MirlitronOne



Joined: Nov 07, 2009
Posts: 77
Location: Surrey, UK
Audio files: 2

PostPosted: Sun Feb 26, 2012 4:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

I agree, the CPC / Farnell search engine is hopeless.

This isn't the exact one that I ordered, but it looks like it has replaced the Spectrasymbol part:

http://uk.farnell.com/multicomp/sp-l-0500-st/sensor-linear-membrane-500mm/dp/1734693

It's the same price and is also available in shorter lengths.

_________________
Life is like an analogue sequencer. Twiddle the knobs to avoid boredom.
Back to top
View user's profile Send private message Visit poster's website
corex



Joined: Mar 02, 2010
Posts: 114
Location: Las Vegas

PostPosted: Tue Mar 06, 2012 12:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm not sure how Mouser is from the UK, but it's easy to find Spectra Symbol SoftPot ribbons, in sizes from 25mm to 1000mm:
http://www.mouser.com/Search/Refine.aspx?Keyword=softpot
Back to top
View user's profile Send private message
vladosh



Joined: Aug 02, 2010
Posts: 422
Location: macedonia
Audio files: 6

PostPosted: Fri Mar 09, 2012 9:10 am    Post subject: Reply with quote  Mark this post and the followings unread

greetings
This has also been on my - to do list . Well i guess ,who wouldn't want a TWO note ribon controller ,sounds more than great , i hope you folks can sort it out somehow ,it's just in some old post here on the forum there was someone who made some mods with success ,or he just said he did ,but what should be done i have no idea , anyway good luck with your work
vlad
Back to top
View user's profile Send private message
frijitz



Joined: May 04, 2007
Posts: 1712
Location: NM USA
Audio files: 54

PostPosted: Sun Oct 21, 2012 12:13 pm    Post subject: Reply with quote  Mark this post and the followings unread

I looked at this several years ago and never got it to work. I took a deeper look at this just the other day. A quick circuit analysis suggests that the Track/Hold cannot possibly work correctly.

The T/H is operated by the "Trigger proc." section, ie the circuitry around IC3C. IC3C fires the Hold function when pin 10 goes below zero volts. This happens when the (smoothed) input signal goes below 0.24 volts. This is the voltage that is held. Always. Capacitor C2 discharges slowly through R24 when the finger contact is removed, so what you hear is a slow sweep down to the pitch corresponding to 0.24 V.

I wrote PAIA the other day to see if they could explain what's going on, but the guy there has no experience with the circuit and does not have a working version to look at. He didn't seem to understand the analysis I gave above.

I've scratched my head to see if the problem could be explained by some small error on the schematic, but so far I have come up blank.

I gave a fairly simple circuit that works well with the Softpot here:
http://www.electro-music.com/forum/topic-32246.html
The latest version is a bit of an improvement, but not by much.

Ian
Back to top
View user's profile Send private message
MirlitronOne



Joined: Nov 07, 2009
Posts: 77
Location: Surrey, UK
Audio files: 2

PostPosted: Sun Oct 21, 2012 4:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

Many would-be Nobel Laureates have spent huge amounts of effort trying to make sense of the last writings of Albert Einstein. Unfortunately, it appears to have been what might be euphemistically referred to as "not his best work". In other words, he was way off the mark.

Sadly, I think that, in a very real sense, this presumably untested circuit was not John Simonton's best work either. I wish Paia would take this misleading document off their website.

Thanks Ian for pointing out your contribution, which presumably is tested. I became so frustrated with the Paia circuit that my most recent thoughts have been to press an Arduino into action to do the difficult stuff in conjunction with a dual serial DAC for output. However, it's a little way down the 'to-do' list.

_________________
Life is like an analogue sequencer. Twiddle the knobs to avoid boredom.
Back to top
View user's profile Send private message Visit poster's website
frijitz



Joined: May 04, 2007
Posts: 1712
Location: NM USA
Audio files: 54

PostPosted: Sun Oct 21, 2012 5:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

MirlitronOne wrote:
...Sadly, I think that, in a very real sense, this presumably untested circuit was not John Simonton's best work either.

I guess we will never know the whole story here. Maybe a schematic got switched or something. It's certainly difficult to concentrate on anything -- even your life's work --when you have serious medical issues.

Quote:
Thanks Ian for pointing out your contribution, which presumably is tested.

Yep, have it sitting right here in a little white project box. It seems to work well with the softpot. There's a bit of a squish factor that changes the pitch a bit on release, but I've learned to compensate for that by rolling my finger a tad as I raise it.

There have been a couple of changes to the circuit to make it respond a bit faster and to reduce the levels into the CA3280 (5V input max on that one!) I should probably put up a modified schematic. It's a slightly "nicer" circuit, but I don't think it works much better in practice.

Quote:
I became so frustrated with the Paia circuit that my most recent thoughts have been to press an Arduino into action to do the difficult stuff in conjunction with a dual serial DAC for output. However, it's a little way down the 'to-do' list.

Yeah, I've been thinking about getting a touch screen for this and other applications. Lots of possibilities once you go to digital. (You've seen bebot? Linked by Howard in the other thread.)

Ian
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic
Page 1 of 1 [11 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » PAIA Equipment
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
e-m mkii

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use