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
  EdisonRex Edison's Electronic Review
Please visit the chat
 Forum index » DIY Hardware and Software » YuSynth
Yusynth CV standards
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [14 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
Funky40



Joined: Sep 24, 2005
Posts: 875
Location: Swiss
Audio files: 1
G2 patch files: 5

PostPosted: Mon Aug 25, 2008 3:26 am    Post subject: Yusynth CV standards
Subject description: recommendations for measuring Equipment required
Reply with quote  Mark this post and the followings unread

Hello Yves,

I'd like to build the CV standards, a really important project. Boards are allready here,
But:

What Equipment do i need to measure the voltages accurate enough.
My DMM is definitly not good enough.

Yves, do you have some recommendations for a good DVM ?
Whats the pricerange one must think of ?
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1234
Location: France

PostPosted: Mon Aug 25, 2008 4:42 am    Post subject: Reply with quote  Mark this post and the followings unread

As a matter of fact one needs a 1mV accuracy for the octave switch and a 0.1mV (or better 0.01mV) accuracy for the semi-tone switch.
As such a 4000/5000 pts DVM will do (let you measure up to 4volts with a 1mV accuracy), personnally I have 50000pts DVM which provides me with a high resolution (let you measure up to 40 volts with a 1mV accuracy).
Obviously the cost of a 20000/50000pts DVM is not the same as that of a 4000pts one.

I bought mine at conrad's some seven years ago and this model is no longer sold but a good one would be (at conrad.ch):
EXTECH EX-510 (6000pts, 175 CHF)
or even better the
Voltcraft VC-860 (40000 pts, 190 CHF ! )

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
Funky40



Joined: Sep 24, 2005
Posts: 875
Location: Swiss
Audio files: 1
G2 patch files: 5

PostPosted: Wed Aug 27, 2008 1:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you Yves.
so it seems all about the points.
when i looked at Mouser they speak from digits. 5 1/2 for example.
ok, i check some places. ( i found nothing at Reichelt yesterday )
Back to top
View user's profile Send private message
Jaba



Joined: Feb 27, 2009
Posts: 47
Location: Genova, Italy

PostPosted: Wed May 13, 2009 5:45 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello,

I am building your Yusynth CV Standards module, on a PCB I bought from Bridechamber (a great PCB! Smile ), but I want to be sure about some details

Confused I just don't understand the "IMPORTANT NOTE" on the project page: why must R7 be 156k ? shouldn't the two voltage dividers be symmetrical ? (I mean the positive semitones CV divider made by R5, T11, T12, T13, T14, T15, R6 and the negative semitones CV divider made by R7, T20, T19, T18, T17, T16, R8 ) ; 156k seems a little low too, IMHO

Question and then why did you choose for +5 and -5 semitones ? this way one note in the octave is left out; I would add a +6 (or a -6), using the last position of the switch and one more trimmer

and last: the parts list says "R7,R22 15k" which seems wrong to me

thank you for these great modules and for the time you spend answering these questions Very Happy

P
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1234
Location: France

PostPosted: Wed May 13, 2009 6:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Jaba
Jaba wrote:
Hello,

I am building your Yusynth CV Standards module, on a PCB I bought from Bridechamber (a great PCB! Smile ), but I want to be sure about some details

Confused I just don't understand the "IMPORTANT NOTE" on the project page: why must R7 be 156k ? shouldn't the two voltage dividers be symmetrical ? (I mean the positive semitones CV divider made by R5, T11, T12, T13, T14, T15, R6 and the negative semitones CV divider made by R7, T20, T19, T18, T17, T16, R8 ) ; 156k seems a little low too, IMHO

I can't remember why I wrote this, oviously it must be symmetrical (and was designed as such in the first place) but probably I had to do it to compensate some tolerance problem in the trimmer line up ... never mind try first 180K for R5 and R7 and if you find it difficult to adjust the extreme semi-tone values, apply the // 1.2M resistor trick.

Jaba wrote:
Question and then why did you choose for +5 and -5 semitones ? this way one note in the octave is left out; I would add a +6 (or a -6), using the last position of the switch and one more trimmer

I always hated the sixth semitone (I am kidding). No the fact was that it would result in a non symmetrical organisation... OK the 6th semitone could have been a hidden option not shown on the panel Wink

Jaba wrote:
and last: the parts list says "R7,R22 15k" which seems wrong to me

Yes this line must be removed from the table, I'll do it ASAP. Thanks for pointing this out to me.

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
numbertalk



Joined: May 05, 2008
Posts: 980
Location: Austin, TX
Audio files: 5

PostPosted: Mon Dec 07, 2009 6:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Yves,

Just finished your cv standards module and everything is great except I can't calibrate the -5 semitone setting. It's off by quite a bit (the closest I can get it is -.4223). I noticed while I had this on my bench it was really wanting more than +/-15VDC in order to calibrate everything correctly. For instance, in order to get a -.4166 I need to have my power supply set a bit higher than -15V. Which I could do, but it was a little high and I really don't want to have to recalibrate all my VCOs by changing the voltages of the supply Is there any other way around this - a resistor on the board I could tweak the value of?

EDIT - I just read the above post and I do have the 1.2M resistor in parallel with the 180K resistor. Should I try a different value other than 1.2M here?

Thanks!
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1234
Location: France

PostPosted: Tue Dec 08, 2009 12:28 am    Post subject: Reply with quote  Mark this post and the followings unread

numbertalk wrote:
Hi Yves,

Just finished your cv standards module and everything is great except I can't calibrate the -5 semitone setting. It's off by quite a bit (the closest I can get it is -.4223). I noticed while I had this on my bench it was really wanting more than +/-15VDC in order to calibrate everything correctly. For instance, in order to get a -.4166 I need to have my power supply set a bit higher than -15V. Which I could do, but it was a little high and I really don't want to have to recalibrate all my VCOs by changing the voltages of the supply Is there any other way around this - a resistor on the board I could tweak the value of?

EDIT - I just read the above post and I do have the 1.2M resistor in parallel with the 180K resistor. Should I try a different value other than 1.2M here?

Thanks!


Yes I said above, I had to add the 1.2M in parallel with the 180K to obtain the right voltage. As I said it is due to tolerance problems. 1.2M did the trick on my prototypes, thus try it first and if doesn't do the trick try other values, greater resistor in order to be more positive, smaller resistor to get more positive. Have you tried without the 1.2M resistor ?

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
numbertalk



Joined: May 05, 2008
Posts: 980
Location: Austin, TX
Audio files: 5

PostPosted: Tue Dec 08, 2009 7:35 am    Post subject: Reply with quote  Mark this post and the followings unread

I haven't tried it with just 180K yet. I just went by your website so put the 1.2M in parallel when I built, then I just read this thread last night. I will try just 180K, though it seems like I need to go with a lower resistance. Is there a don't-go-lower-than value for this resistor?

Thanks.

yusynth wrote:
numbertalk wrote:
Hi Yves,

Just finished your cv standards module and everything is great except I can't calibrate the -5 semitone setting. It's off by quite a bit (the closest I can get it is -.4223). I noticed while I had this on my bench it was really wanting more than +/-15VDC in order to calibrate everything correctly. For instance, in order to get a -.4166 I need to have my power supply set a bit higher than -15V. Which I could do, but it was a little high and I really don't want to have to recalibrate all my VCOs by changing the voltages of the supply Is there any other way around this - a resistor on the board I could tweak the value of?

EDIT - I just read the above post and I do have the 1.2M resistor in parallel with the 180K resistor. Should I try a different value other than 1.2M here?

Thanks!


Yes I said above, I had to add the 1.2M in parallel with the 180K to obtain the right voltage. As I said it is due to tolerance problems. 1.2M did the trick on my prototypes, thus try it first and if doesn't do the trick try other values, greater resistor in order to be more positive, smaller resistor to get more positive. Have you tried without the 1.2M resistor ?
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1234
Location: France

PostPosted: Tue Dec 08, 2009 8:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Is there a don't-go-lower-than value for this resistor?


Not really there is no lethal effect Wink I'd say this should not be smaller than 150K. That is in fact a value in between 150K and 180K, so you may try to replace the 1.2M by a 1M and if this doesn't solve the problem use a 820K

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
numbertalk



Joined: May 05, 2008
Posts: 980
Location: Austin, TX
Audio files: 5

PostPosted: Tue Dec 08, 2009 9:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Great thanks!!

yusynth wrote:
Quote:
Is there a don't-go-lower-than value for this resistor?


Not really there is no lethal effect Wink I'd say this should not be smaller than 150K. That is in fact a value in between 150K and 180K, so you may try to replace the 1.2M by a 1M and if this doesn't solve the problem use a 820K
Back to top
View user's profile Send private message
numbertalk



Joined: May 05, 2008
Posts: 980
Location: Austin, TX
Audio files: 5

PostPosted: Tue Dec 08, 2009 7:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok, got it!

One more question, though - I don't seem to have a stable 5VDC source I can use for calibrating the "external cv" trimmers, so I used the highest output of my CV keyboard, since it's very stable - it's 3.903VDC - is this ok or does it really need to be 5V?

Thanks!
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1234
Location: France

PostPosted: Wed Dec 09, 2009 12:27 am    Post subject: Reply with quote  Mark this post and the followings unread

numbertalk wrote:
Ok, got it!

One more question, though - I don't seem to have a stable 5VDC source I can use for calibrating the "external cv" trimmers, so I used the highest output of my CV keyboard, since it's very stable - it's 3.903VDC - is this ok or does it really need to be 5V?

Thanks!


It's OK, what is important is to use a reference voltage that you feed on the EXTERNAL CV input and adjust the trimer in order to retrieve the exact value of the input on the output with the rotaries (octave and semitones) set to the 0 mark.

By the way 3.903V is quite deviant from 4V (4 octaves) for a keyboard, may it needs to be trrimmed too Wink

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
numbertalk



Joined: May 05, 2008
Posts: 980
Location: Austin, TX
Audio files: 5

PostPosted: Wed Dec 09, 2009 8:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks Yves, that's what I thought but wanted to make sure you hadn't picked 5V for some reason I wasn't seeing.

I think the reason that voltage from my keyboard is as far off from 4V as it is is that the highest note is a B, not a C, so it's just under 4 octaves. Still it's not quite perfect and this has made me realize it could use some calibration, so I'll need to figure that out at some point.

A few notes for anyone else building this - I upgraded the op amps to LT1014s for greater stability and accuracy - the pin out is a perfect match for the TL074. Also you should calibrate this module with it connected to your synth's power supply, not your bench supply. If the voltages differ even by a small amount between your bench supply and your synth supply the calibrations will be off. Also as already noted you might need to play around with the value of R7 if you're having trouble particularly trimming the -5 semitone setting. Also if you have any trouble trimming any of the higher or lower values of the octave or semitone settings make sure your supply is calibrated to give +/-15V and not a little under (or else I guess you'll need to tweak the resistors a bit as already noted to compensate for the tolerance values of the trimmers).

I'm very excited to have this module, Yves, thank you so much for this project! Not as glamorous as your filter series but incredibly useful - not to be overlooked! Even aside from the tuning capabilities it offers, having a buffered multiple for reliably distributing critical control voltages to multiple VCOs/modules is a must in any system I think.

yusynth wrote:
numbertalk wrote:
Ok, got it!

One more question, though - I don't seem to have a stable 5VDC source I can use for calibrating the "external cv" trimmers, so I used the highest output of my CV keyboard, since it's very stable - it's 3.903VDC - is this ok or does it really need to be 5V?

Thanks!


It's OK, what is important is to use a reference voltage that you feed on the EXTERNAL CV input and adjust the trimer in order to retrieve the exact value of the input on the output with the rotaries (octave and semitones) set to the 0 mark.

By the way 3.903V is quite deviant from 4V (4 octaves) for a keyboard, may it needs to be trrimmed too Wink
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1234
Location: France

PostPosted: Wed Dec 09, 2009 8:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
I think the reason that voltage from my keyboard is as far off from 4V as it is is that the highest note is a B, not a C, so it's just under 4 octaves.


That makes sense then and yes it may still need some calibration.

You are right to say that it was designed having in mind that the PSU of the modular is well calibrated and delivers the right voltages. I could have included a voltage reference on the PCB to make it independent of the PSU voltages but it was already a very densely populated module...

Enjoy it !

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [14 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 » YuSynth
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