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 » YuSynth
YUSYNTH EMS-diode ladder filter
Post new topic   Reply to topic Moderators: Scott Stites
Page 2 of 6 [129 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Goto page: Previous 1, 2, 3, 4, 5, 6 Next
Author Message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sun Mar 16, 2008 2:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well if it oscillates the problem comes definitely from Q12 or its polarization circuit.
The -3V seems a normal value (divider 680K and two 220K in parallel (R39 and R45 if the ouput (pin 7) of U1b is at 0V.

The sudden change to -1.3V is quite weird indeed... is U1b OK ?
Sounds like something misconnected : is the resonance pot connected to -9V on one side (CW) and to ground (CCW) ?

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



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sun Mar 16, 2008 2:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Could you try flipping the 2N3819, I know that one can find two brands that have opposite pin-outs , that's very puzzling when you check the datasheet from various constructor the pin-out can be reversed. ????

If this does not solve the problem try replacing the 680k by a 220K as in the original schematic. I changed this value to 680K because on my prototypes this change was necessary.

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



Joined: May 26, 2007
Posts: 413
Location: England
Audio files: 3

PostPosted: Sun Mar 16, 2008 7:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
could you try flipping the 2N3819, I know that one can find two brands that have opposite pin-outs , that's very puzzling when you check the datasheet from various constructor the pin-out can be reversed. ????


Hi Yves.
That's very valuable information - thanks. I have a few EFM modules that use 2N3819s. On the datasheets I've got, the fairchild component has this - with the flat side of the TO-92 case flat down on the table , and the legs pointing towards you, it goes Source, gate, drain (left to right). The vishay part is the opposite! This *might* explain the failure of the S+H section on some EFMLFO5As to actually sample and hold. Fonik had this problem IIRC, and one of mine didn't do the business either....

I seem to remember reading somewhere that drain and source were often interchangeable? scratch It seems that they aren't....
Can anyone confirm or deny this? The last few 2N3819s I have are unbranded. so, er, I might get into some trouble......

cheers,
Dave
Back to top
View user's profile Send private message
Etaoin



Joined: Jun 30, 2005
Posts: 760
Location: Utrecht, NL

PostPosted: Sun Mar 16, 2008 11:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

yusson wrote:
Could you try flipping the 2N3819, I know that one can find two brands that have opposite pin-outs , that's very puzzling when you check the datasheet from various constructor the pin-out can be reversed. ????


Yeah, I knew about that one so I had already checked this. But I have a marked Fairchild FET, so there was little doubt.

Quote:
If this does not solve the problem try replacing the 680k by a 220K as in the original schematic.


That worked! Seems to be fine now...

_________________
http://www.casia.org/modular/
Back to top
View user's profile Send private message Visit poster's website MSN Messenger
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Mon Mar 17, 2008 12:05 am    Post subject: Reply with quote  Mark this post and the followings unread

OK then I will add a note on my page that the value of this resistor must be adapted to the 2N3819 used or may be is it due to the use of B brand which gives a lower gain. On my proptotype I used C brand which gives a higher gain and I add to increase the resistance from 220K to 680K in order to obtain a resonance range that spread nicely over the pot run.

Cheer Louis

_________________
Yves
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: Mon Mar 17, 2008 2:01 am    Post subject: Reply with quote  Mark this post and the followings unread

yusson wrote:
OK then I will add a note on my page that the value of this resistor must be adapted to the 2N3819 used or may be is it due to the use of B brand which gives a lower gain. On my proptotype I used C brand which gives a higher gain and I add to increase the resistance from 220K to 680K in order to obtain a resonance range that spread nicely over the pot run.

Aren't you just seeing variations in pinchoff voltage from device to device? I have a bank of six VCAs made from FET-based variable resistors, and I had to select devices for the same pinchoff. But the response is so sensitive to pinchoff that I had to trim the bias points by hand to get even close to the same range on each channel. And this was with devices from the same batch. Look at the specified pinchoff voltage and you will see there is a huge range.

Very Happy

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



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Mon Mar 17, 2008 4:09 am    Post subject: Reply with quote  Mark this post and the followings unread

frijitz wrote:

Aren't you just seeing variations in pinchoff voltage from device to device? I have a bank of six VCAs made from FET-based variable resistors, and I had to select devices for the same pinchoff. But the response is so sensitive to pinchoff that I had to trim the bias points by hand to get even close to the same range on each channel. And this was with devices from the same batch. Look at the specified pinchoff voltage and you will see there is a huge range.

Very Happy

Ian


Yes that was my first hypothesis but I was not sure,
Quote:
the value of this resistor must be adapted to the 2N3819 used
your info about FET from the same batch with such variations is very interesting indeed

Cheers

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



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Tue Aug 12, 2008 6:24 am    Post subject: Reply with quote  Mark this post and the followings unread

I have updated (august 12th 2008) my diode-ladder filter page.
I just changed the value of R47 from10K to 39K which seems to give a better output level (at least in the range of the other yusynth VCFs anyway).

Cheers

_________________
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: Sat Sep 13, 2008 9:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello Yves,

i see at Reichelt that the BC327 is available in different types.
BC 327-16 / -25 / -40
which one should i take ?

edit:
uhhh, the 2N3819 costs 20 times more at conrad then at Reichelt.
are there different Qualitys available ? something to care ? ( i have to Order at both places )



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



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sat Sep 13, 2008 9:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi

The brand of BC327 is not important you can pick any of these.

For the 2N3819, take the cheapest. Active components at Conrad's are well overpriced !

Wink

_________________
Yves

Last edited by yusynth on Tue Sep 30, 2008 11:05 am; edited 1 time in total
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 Sep 30, 2008 10:34 am    Post subject: Reply with quote  Mark this post and the followings unread

So this would be pin 2 of the CA3046, right? On the PCB you would just tap an output somewhere in the trace between pin 2 and R13 and would connect the positive lead of the cap to this side and then the negative lead to 0V, right?

yusson wrote:
OK I checked the bubbly stuff in Autobahn and I understand what you mean.
I also checked the various EMS schematics I have and apparently I have two versions, one is a polarized cap connected to the base of Q4 (first transistor of the expo converter) which I considered as a design mistake and a second version where the very same cap is connected between the negative rail and ground which makes sense indeed. In my "clone" I suppressed this cap.
If you want to recreate this bug/feature of the old version you will have to add a 10uF cap between the base of Q4 and the 0V level.
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Tue Sep 30, 2008 11:11 am    Post subject: Reply with quote  Mark this post and the followings unread

numbertalk wrote:
So this would be pin 2 of the CA3046, right? On the PCB you would just tap an output somewhere in the trace between pin 2 and R13 and would connect the positive lead of the cap to this side and then the negative lead to 0V, right?

yusson wrote:
OK I checked the bubbly stuff in Autobahn and I understand what you mean.
I also checked the various EMS schematics I have and apparently I have two versions, one is a polarized cap connected to the base of Q4 (first transistor of the expo converter) which I considered as a design mistake and a second version where the very same cap is connected between the negative rail and ground which makes sense indeed. In my "clone" I suppressed this cap.
If you want to recreate this bug/feature of the old version you will have to add a 10uF cap between the base of Q4 and the 0V level.


Hi Paul

No it's pin 9 as a matter of fact, therefore you just need to solder a 10uF cap in parallel with R22 (1K)...

Here is a tip : for those of you who want to obtain a genuine EMS sound while using DOTCOM or YUSYNTH VCOs it is recommended to change the value of R8 to 27K. The output levels of these VCOs are much higher than those of an AKS and this makes a big difference in sound.

I have recently added a demo file on the diode VCF page... Check it out.

_________________
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 Sep 30, 2008 11:30 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks Yves!

So if I wanted to wire this up through a toggle, does it matter which end of the cap is left floating when the switch is bypassed? Should I hard wire the cap between ground and the switch or to the lead out of pin 9 and the switch or does it not matter? I'm going to guess if it matters it would be to ground, so any signals or what not picked up would be shunted to ground.
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Tue Sep 30, 2008 11:49 am    Post subject: Reply with quote  Mark this post and the followings unread

numbertalk wrote:
Thanks Yves!

So if I wanted to wire this up through a toggle, does it matter which end of the cap is left floating when the switch is bypassed? Should I hard wire the cap between ground and the switch or to the lead out of pin 9 and the switch or does it not matter? I'm going to guess if it matters it would be to ground, so any signals or what not picked up would be shunted to ground.


Yes the best is to leave the cap connected to the ground and insert the switch between the cap and pin 9.

As a matter of fact I have added this mod on the PCB that is used by Suit&Tie Guy for the Sea Devil filter Wink

_________________
Yves

Last edited by yusynth on Tue Sep 30, 2008 12:41 pm; edited 1 time in total
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 Sep 30, 2008 12:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

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



Joined: Feb 05, 2007
Posts: 29
Location: Chillicothe IL USA

PostPosted: Sun Oct 05, 2008 7:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

FYI currently the resistor changes i'm using for 10v p-p signal levels are the aforementioned 27K, but also the 2.2K shunt to ground is changed to 220 ohm, and the feedback resistor on the output opamp is changed to 15K instead of 10K.

i'm still fussing with it, but these values seem to work well.
Back to top
View user's profile Send private message Visit poster's website AIM Address
Funky40



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

PostPosted: Sat Oct 18, 2008 8:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Etaoin wrote:
The filter works fine, but I only have a bit of resonance if I turn the res pot fully CW and put a large CV into the red mod input. With large enough CV, the res pot works as expected, with no CV, the res pot doesn't do anything. .

Just wired the Yusynth Diode Ladder VCF
I had the very same Problem.
First thing i tryed was to change as mentioned above the 680K Res to 220K.
Now i have Resonance.
Seems to work fine now ! thanks for that Module Yves
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sat Oct 18, 2008 9:14 am    Post subject: Reply with quote  Mark this post and the followings unread

You're welcome Funky40 !
_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
stijn



Joined: Jul 21, 2008
Posts: 39
Location: utrecht, netherlands

PostPosted: Thu Nov 20, 2008 12:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Yves,

I am about finished populating the board. The bom on your site states that 5 100nF caps are needed, but on the board (bridechamber) there is 6 needed. Is this correct?
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Thu Nov 20, 2008 12:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Stijn

6 is the right number , I forgot one on the BOM on my site , I will correct this ASAP Wink

Have fun with this great filter.

Cheers

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



Joined: Jul 21, 2008
Posts: 39
Location: utrecht, netherlands

PostPosted: Sun Dec 21, 2008 4:31 am    Post subject: Reply with quote  Mark this post and the followings unread

well I seem to have the opposit problem, my filter self oscillates all the time. resonance pot doesn't do anything. For the rest the filter is working fine.
Where should I look to solve this problem?
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sun Dec 21, 2008 4:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Is C14 (100uF) polarised the right way (- to FET drain and + to R42/R40)?

On first analysis I'd say there is either a dead FET or a faulty polarisation of the Fet grid. Are you using a 2N3819 ? If so is it correctly placed that is as shown on the silkscreen ?
After check the voltage at the G pin of the FET, when tweaking the resonance pot this value must vary from 0V down to -2.4V (for R41=680K) or -5V (for R41=220K).
I all these are correct you may try increasing the value of R41

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



Joined: Jul 21, 2008
Posts: 39
Location: utrecht, netherlands

PostPosted: Sun Dec 21, 2008 8:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Ives,

the polarization of the cap and fet are ok, the voltege at the G pin varies from 0,32 to - 0,47 V when tweaking the resonance pot (I am using a 22k resistor for R41). Oh and I am testing it with a +12/-12 V power supply.
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sun Dec 21, 2008 8:31 am    Post subject: Reply with quote  Mark this post and the followings unread

stijn wrote:
the voltege at the G pin varies from 0,32 to - 0,47 V when tweaking the resonance pot (I am using a 22k resistor for R41). Oh and I am testing it with a +12/-12 V power supply.

It should vary from 0 to -2.4V !!!!! and 22K for R41 is way too SMALL !!!! It should be at least 220K!!!!!

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



Joined: Jul 21, 2008
Posts: 39
Location: utrecht, netherlands

PostPosted: Sun Dec 21, 2008 8:41 am    Post subject: Reply with quote  Mark this post and the followings unread

yusson wrote:
stijn wrote:
the voltege at the G pin varies from 0,32 to - 0,47 V when tweaking the resonance pot (I am using a 22k resistor for R41). Oh and I am testing it with a +12/-12 V power supply.

It should vary from 0 to -2.4V !!!!! and 22K for R41 is way too SMALL !!!! It should be at least 220K!!!!!


off course I mean 220k Embarassed
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 2 of 6 [129 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2, 3, 4, 5, 6 Next
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