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
VCF circuit to run off batteries?
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
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
gmeredith



Joined: Jun 28, 2006
Posts: 82
Location: Tasmania, Australia
Audio files: 1

PostPosted: Tue Aug 15, 2006 7:38 pm    Post subject: VCF circuit to run off batteries? Reply with quote  Mark this post and the followings unread

Here I go again, something extra for my freaked out mega Casio SK8!! afro

I want to add a VCF to it. There are 4 separate output lines (for each voice of its 4 note polyphony) that go directly from the processor/ROM, outputting the raw samples, which then feed into a VCA chip.

I was wanting to slip a VCF in between these components. All the VCF circuits I have found so far all run off dual rail + - supplies, not single rail, battery level supplies. The Casio has 2 voltage levels inside: +5V for the logic, and about +10V for the audio. I could use either one of these to power a circuit.

Is there any VCF circuits out there that will run off 5-10V DC single rail? With some sort of ADSR and resonance, and CV in?

In reality, I suspect that I will actually need 4 VCF circuits, one for each voice, so a quad VCF would be nice, but I'll take what I can get at this stage, as I'm still 'loinin Mr. Green

Cheers, Graham
Back to top
View user's profile Send private message
zipzap



Joined: Nov 22, 2005
Posts: 559
Location: germany
Audio files: 24

PostPosted: Wed Aug 16, 2006 4:27 am    Post subject: Reply with quote  Mark this post and the followings unread

I have some circuits somewhere, see if i can find them. Basically it should be no problem. You definatly want to use the analog 10v supply. First of all it gives you more headroom, secondly most single supply designs i know run between 9-12v, and most important you want to keep that logic supply with the logic.
I´ll have a look, in any case, for single supply designs it´s good to look at guitareffect diy pages. They normaly run on single 9v bateries.

_________________
http://www.myspace.com/lorolocoacousticpop
http://www.myspace.com/petrolvendor
music and transcribed jazz basslines
Back to top
View user's profile Send private message
zipzap



Joined: Nov 22, 2005
Posts: 559
Location: germany
Audio files: 24

PostPosted: Wed Aug 16, 2006 4:38 am    Post subject: Reply with quote  Mark this post and the followings unread

The wasp filter works on single supply i think. And the other schematic is the one i thought of. It´s from this great page with masses of 9v effects. What you´re doing sounds like a really cool idea. maybe you want to add some more effects...
http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html#lofomofo
In case some unsolvable trouble accurs, you can alwys hang a filter after the vcas.


sk.gif
 Description:
 Filesize:  6.88 KB
 Viewed:  4406 Time(s)

sk.gif



_________________
http://www.myspace.com/lorolocoacousticpop
http://www.myspace.com/petrolvendor
music and transcribed jazz basslines
Back to top
View user's profile Send private message
gmeredith



Joined: Jun 28, 2006
Posts: 82
Location: Tasmania, Australia
Audio files: 1

PostPosted: Wed Aug 16, 2006 4:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks, zipzap that is a great site! I think I found one that is a good starter - it also has a CV input.

I'm still a bit of a noob - what does the symbol "Vr" stand for in this circuit? and the little isolated schematic that has +9V at the top of it - where does that fit in the circuit?

Cheers, Graham


quad vcf res cv.JPG
 Description:
 Filesize:  93.65 KB
 Viewed:  150 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

quad vcf res cv.JPG


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


Joined: Apr 03, 2004
Posts: 20623
Location: The Netherlands, Enschede
Audio files: 150
G2 patch files: 318

PostPosted: Wed Aug 16, 2006 5:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

gmeredith wrote:
what does the symbol "Vr" stand for in this circuit? and the little isolated schematic that has +9V at the top of it - where does that fit in the circuit?


Vr stands for reference voltage. That little circuit "makes" Vr (equal to 4.5 V). This a trick really to make it possible for opamp circuits to using a single supply.

Usually opamp circuits use a power supply with both a positive and a negative supply voltage (or supply rail). In such a circuit an input of an opamp can be connected to the ground, which is inbetween the positive and the negative supply voltage, and "by definition" at 0 Volts.

For opamp circuits that use only a zero and a (usually) positive supply a trick is needed as opamp inputs don't feel at ease (the opamp will be used outside it specificated operating range) when connected to either supply voltage. So the conection to the 0 Volt rail can't be used here. Instead a reference voltage can be generated then to which such opamp inputs are then connected instead. The reference voltage is usually in the middle between the positive and negative rails, which then sort of equals the situation as described in the previous paragraph.

The relatively large capacitor that is used in the "little circuit" makes it look for AC signals as if the reference still is a true zero signal. The trick is just meant to keep the opamps with operating ranges while for the processed signals it still looks as if the circuit were using a dual supply.

_________________
Jan
Back to top
View user's profile Send private message Visit poster's website
gmeredith



Joined: Jun 28, 2006
Posts: 82
Location: Tasmania, Australia
Audio files: 1

PostPosted: Wed Aug 16, 2006 5:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ahh, so then the little separate circuit with the +9V at the top is the Vr supply circuit, to which its Vr output line connects to all of the other Vr labelled lines in the big circuit? I think I got it!

Cheers, Graham
Back to top
View user's profile Send private message
Blue Hell
Site Admin


Joined: Apr 03, 2004
Posts: 20623
Location: The Netherlands, Enschede
Audio files: 150
G2 patch files: 318

PostPosted: Wed Aug 16, 2006 5:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

Think so Very Happy
_________________
Jan
Back to top
View user's profile Send private message Visit poster's website
gmeredith



Joined: Jun 28, 2006
Posts: 82
Location: Tasmania, Australia
Audio files: 1

PostPosted: Wed Aug 16, 2006 6:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for your help!! I have a TL071 op amp lying around. Would that be suitable for the circuit?

Cheers, Graham
Back to top
View user's profile Send private message
zipzap



Joined: Nov 22, 2005
Posts: 559
Location: germany
Audio files: 24

PostPosted: Thu Aug 17, 2006 12:25 am    Post subject: Reply with quote  Mark this post and the followings unread

It should.
_________________
http://www.myspace.com/lorolocoacousticpop
http://www.myspace.com/petrolvendor
music and transcribed jazz basslines
Back to top
View user's profile Send private message
trevize



Joined: Jul 23, 2006
Posts: 3
Location: Venice (Italy)

PostPosted: Thu Aug 17, 2006 2:15 am    Post subject: Reply with quote  Mark this post and the followings unread

i did the pcb of the quick&dirty vcf in eagle cad if you want i can send you the files.
Back to top
View user's profile Send private message
gmeredith



Joined: Jun 28, 2006
Posts: 82
Location: Tasmania, Australia
Audio files: 1

PostPosted: Thu Aug 17, 2006 6:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks, trevize! My email is:

gmeredith1 at yahoo dot com dot au

Cheers, Graham

Last edited by gmeredith on Sun Aug 20, 2006 7:00 pm; edited 1 time in total
Back to top
View user's profile Send private message
zipzap



Joined: Nov 22, 2005
Posts: 559
Location: germany
Audio files: 24

PostPosted: Fri Aug 18, 2006 1:30 am    Post subject: Reply with quote  Mark this post and the followings unread

I would advise you to send your email in a PM! You know there´s spambots that collect everything on the web that looks like a email adress. I´ve already had burned adresses...
_________________
http://www.myspace.com/lorolocoacousticpop
http://www.myspace.com/petrolvendor
music and transcribed jazz basslines
Back to top
View user's profile Send private message
trevize



Joined: Jul 23, 2006
Posts: 3
Location: Venice (Italy)

PostPosted: Fri Aug 18, 2006 7:55 am    Post subject: Reply with quote  Mark this post and the followings unread

zipzap is right! edit your post as soon as possible, btw email sent!
Back to top
View user's profile Send private message
gmeredith



Joined: Jun 28, 2006
Posts: 82
Location: Tasmania, Australia
Audio files: 1

PostPosted: Sun Aug 20, 2006 7:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks, guys, done!! Pesky 'bots!!

Thanks, Trevize, for the PCB layout, that's great!!

Cheers, Graham
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
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
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