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
Question about PAIA 2720-3L LPF design
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
Page 1 of 1 [7 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
lostinpurdy



Joined: Nov 16, 2007
Posts: 37
Location: Gig Harbor

PostPosted: Tue Nov 06, 2012 9:47 am    Post subject: Question about PAIA 2720-3L LPF design
Subject description: modify to adjust resonance?
Reply with quote  Mark this post and the followings unread

The PAIA 2720 LPF seems to be a simple enough design for me to put together but I do have one question about it though - is it possible to modify it in a way so that it's possible to control the resonance as well, and what would be the simplest method to accomplish this? I would really like to keep the circuit as simple and low parts as possible.



Posted Image, might have been reduced in size. Click Image to view fullscreen.[/img]
Back to top
View user's profile Send private message
Psyingo



Joined: Jun 11, 2009
Posts: 247
Location: Canada

PostPosted: Thu Nov 08, 2012 7:34 am    Post subject: Reply with quote  Mark this post and the followings unread

The paia 2700 lpf doesn't have resonance. You would have to do some serious modifications to it to make it resonant.

If you want a simple resonant filter, i hear the wsg filter by music from outer space is popular.
Back to top
View user's profile Send private message Visit poster's website MSN Messenger
valis



Joined: Sep 16, 2008
Posts: 121
Location: Oregon, USA
Audio files: 6

PostPosted: Sun Nov 11, 2012 11:51 am    Post subject: Reply with quote  Mark this post and the followings unread

As far as PAiA filters go, it sounds like the 2720-5 resonant BPF might be a better option for you. It's a simple circuit. You can change the range of the filter to better suit your needs by proportionally altering C3, C4, and C5. Halving the values should double both the high and low end of the filter.





Posted Image, might have been reduced in size. Click Image to view fullscreen.
Back to top
View user's profile Send private message
Cynosure
Site Admin


Joined: Dec 11, 2010
Posts: 692
Location: Toronto, Ontario - Canada
Audio files: 39

PostPosted: Sun Nov 11, 2012 1:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

I have something very similar to the Paia filter that is both lowpass and bandpass. I haven't posted the schematic yet because I am still working on soldering it all together with the rest of the project. I will cut out the filter part and post it later today.
Back to top
View user's profile Send private message
Cynosure
Site Admin


Joined: Dec 11, 2010
Posts: 692
Location: Toronto, Ontario - Canada
Audio files: 39

PostPosted: Sun Nov 11, 2012 2:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok here is the schematic.

It is the same filter from the LM13700 datasheet but with a resonance loop and pot added to the first stage of the filter.

The control voltage is from -5V to +5V, but if you tweak the values of C47 and C48 you should be able to get it to work from 0V to +5V.

If all you want is the lowpass portion then you can leave out the TL opamp and just take the output from C37. That part was just added to boost the bandpass output level.


simple_lp_bp.png
 Description:
 Filesize:  21.94 KB
 Viewed:  90 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

simple_lp_bp.png


Back to top
View user's profile Send private message
Cynosure
Site Admin


Joined: Dec 11, 2010
Posts: 692
Location: Toronto, Ontario - Canada
Audio files: 39

PostPosted: Mon Nov 12, 2012 7:17 am    Post subject: Reply with quote  Mark this post and the followings unread

For some reason your schematic wasn't showing up for me and I thought you meant the svf in the fatman. The one you are looking at is actually a lot mor simple than the one I posted.

It looks like a sallen key filter. Maybe try looking at some schematics for those and see how they add resonance. Or try just creating your own feedback loop with a buffer like in the MS20 filter. Try by starting with A3 from this:

http://www.uni-bonn.de/~uzs159/rs20.png
Back to top
View user's profile Send private message
Psyingo



Joined: Jun 11, 2009
Posts: 247
Location: Canada

PostPosted: Mon Nov 12, 2012 10:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Neither the 2720-3L or 2720-3b are sallen keys. Resonance will not be as easy as adding a feedback path unfortunately.
Back to top
View user's profile Send private message Visit poster's website MSN Messenger
Display posts from previous:   
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
Page 1 of 1 [7 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
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