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
<on air> Jez Adventures in Sound
Please visit the chat
 Forum index » DIY Hardware and Software
VCO Modulation
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
Page 1 of 1 [24 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Fri Oct 25, 2013 11:29 pm    Post subject:  VCO Modulation Reply with quote  Mark this post and the followings unread

Hi guys.

need help with in wiring Embarassed

building a new synth and i want the ability to send one LFO to the 2 vco's separately and together, meaning...
using on-off-on toggle switch:
left side "ON" will be VCO 1
right side "ON" will be VCO 2
center "OFF" will be VCO 1 and 2.
is it possible to do?

i was stayed up late trying to drew this but didnt got to any solutions.
if you guys have any idea of how to do it i'll be happy to hear, as long as its with 3way toggle switch.

attached is the basic idea.
the buffer is for the 2 vco's from one LFO.

cheers.
Isak E.


vco modulation.png
 Description:
 Filesize:  22.25 KB
 Viewed:  21 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

vco modulation.png



_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
analogmonster



Joined: May 30, 2011
Posts: 13
Location: Germany

PostPosted: Fri Oct 25, 2013 11:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

As you can't route a signal thru an "off" position directly you need additional logic like electronic switches driven by the "on" positions and an inverter in the "off" case.

Easier way would be to use a three position rotary switch Razz

_________________
Regards

Carsten
http://www.analog-monster.de/index_en.html
Back to top
View user's profile Send private message Visit poster's website
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Sat Oct 26, 2013 12:15 am    Post subject: Reply with quote  Mark this post and the followings unread

I though it would be the answer.
I don't have space for additional rotary switch.

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
gdavis



Joined: Feb 27, 2013
Posts: 150
Location: San Diego

PostPosted: Sat Oct 26, 2013 9:22 am    Post subject: Reply with quote  Mark this post and the followings unread

This is my circuit to do exactly what you're talking about, not fully tested yet though.

Replace R5 and the circuit to the left of it with your LFO output.

SEL_A and SEL_B are connected to each end lug of the switch, center lug is connected to ground.

When the panel switch is open, R6 and R7 pull up the control inputs to turn on the LFO to the VCO's. When the switch is closed one way or the other, that control input is grounded turning off the LFO to the corresponding VCO.


vco_mod_switch.png
 Description:
 Filesize:  17.99 KB
 Viewed:  25 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

vco_mod_switch.png



_________________
My synth build blog: http://gndsynth.blogspot.com/
Back to top
View user's profile Send private message
thermionicjunky



Joined: Dec 07, 2006
Posts: 72
Location: san francisco

PostPosted: Sat Oct 26, 2013 8:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

You can wire up a C&K 7211 DPDT as an on-on-on with one position connected to VCO 1, another to VCO 2 and the third to both. A diagram can be found here:

http://www.simple-answer.com/DIY.html
Back to top
View user's profile Send private message
AndyR1960



Joined: Feb 16, 2007
Posts: 281
Location: Manchester UK
Audio files: 5

PostPosted: Sun Oct 27, 2013 12:07 am    Post subject: Reply with quote  Mark this post and the followings unread

...or try a 2P3T switch.

Centre position = Mod to both VCO's
Left Position = Mod to VCO 1
Right Position = Mod to VCO2

The problem is getting hold of a 2P3T toggle switch - I've only seen them in slide (eg. Fender Mustang Switch)


2P3T Switch.jpg
 Description:
 Filesize:  56.87 KB
 Viewed:  2637 Time(s)

2P3T Switch.jpg


Back to top
View user's profile Send private message
AndyR1960



Joined: Feb 16, 2007
Posts: 281
Location: Manchester UK
Audio files: 5

PostPosted: Sun Oct 27, 2013 12:31 am    Post subject: Reply with quote  Mark this post and the followings unread

thermionicjunky wrote:
You can wire up a C&K 7211 DPDT as an on-on-on with one position connected to VCO 1, another to VCO 2 and the third to both. A diagram can be found here:

http://www.simple-answer.com/DIY.html


I didn't quite understand the diagram at first, but there's a simple slide show explaining it here :

http://www.youtube.com/watch?v=14i2B8scNaI

If only I'd known about this before I ordered a bunch of rather expensive Fender 2P3T switches Rolling Eyes
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Sun Oct 27, 2013 5:00 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks guys.

Even after seen the tube vid I don't understand the logic of it Embarassed Confused
I see it is a regular on off on switch, it's the wiring and the outputs I don't understand..

EDIT:
Ok, so if I understadnd this correctly by the tube vid..
A is down
C is up
B is center

?

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
gdavis



Joined: Feb 27, 2013
Posts: 150
Location: San Diego

PostPosted: Sun Oct 27, 2013 10:58 am    Post subject: Reply with quote  Mark this post and the followings unread

That's actually not quite what you need. It connects "common" to one of three different points. Though I guess you could connect "center" to both VCO's to get what you want, but this might be a little cleaner:


DPDTonononSP3T.png
 Description:
 Filesize:  10.62 KB
 Viewed:  2530 Time(s)

DPDTonononSP3T.png



_________________
My synth build blog: http://gndsynth.blogspot.com/
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Sun Oct 27, 2013 1:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Now I understand what I don't understand.

As I see the layout you show me is on on on, the red lines are changing by the switch position, the blue line is a jumper, till here I'm ok.
In the on off on switch I don't get the red lines like in the on on on switch.
This is got me confused.
I see that when the on on on switch is in center position it shorts from the upper right to center and the lower left to center which I don't get in the on off on switch.

I guess the conclusion is I will need an on on on switch and can't do this with on off on switch, right?

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1472
Location: Chicago
Audio files: 14

PostPosted: Sun Oct 27, 2013 6:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

I think the point is that the on-on-on switch would be more straightforward (once you wrap your head around it--a tough job, it took me a while too). You can use on-off-on, but you'll have to add additional logic and something like a 4066 switch to route the signals the way you have stated, whereas with the on-on-on it's just a wiring exercise. A tricky one, but still you basically just wire your inputs to the right places, and a common to the next stage, and you're done.


Here's Scott Stites' version of explaining the switch, you may find it easier to follow. As someone else already said, you could wire it so that each VCO was connected to one 'side' of the switch, and the center position would combine them--assuming you had summing resistors before the switch.

http://www.birthofasynth.com/Thomas_Henry/Images/SN-Voice_construction/c&k7211_3way.jpg

Edit: I'd wire VCO1 to pin 3, VCO2 to pin 4, wire 5 & 2 together and run them to the thing that was taking the sum (likely an op amp). Or maybe reverse pins 3 & 4 if I got the direction of the switch wrong Very Happy
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Mon Oct 28, 2013 7:54 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks, all the time I was thinking they takes about the on off on switch, this I why I got confused.

Now its all clear to me Smile
Any source to the on on on switch?
All I find in eBay is the on off on, not on on on.

Cheers.

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1472
Location: Chicago
Audio files: 14

PostPosted: Mon Oct 28, 2013 9:25 am    Post subject: Reply with quote  Mark this post and the followings unread

I bought some from Mouser....
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Mon Oct 28, 2013 11:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

The problem with mouser is the expensive shipping.
If you don't make a BIG buy it's not worth the shipping.

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1472
Location: Chicago
Audio files: 14

PostPosted: Tue Oct 29, 2013 4:48 am    Post subject: Reply with quote  Mark this post and the followings unread

I would imagine there are other sources, but I'm at a point where EBay is last resort, because I've been burned and hear too many bad stories.
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Tue Oct 29, 2013 5:38 am    Post subject: Reply with quote  Mark this post and the followings unread

elmegil wrote:
I would imagine there are other sources, but I'm at a point where EBay is last resort, because I've been burned and hear too many bad stories.

its depends, you need to know from who to buy.
i have my my fav shops, only from there im ordering, never failed me.
i ordered some TL074 from unknown source and got burned so i know what your talking about.

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
Sebo



Joined: Apr 27, 2007
Posts: 538
Location: Argentina

PostPosted: Thu Oct 31, 2013 8:15 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi:
May be you can try a circuit like the one used in panpots.
Connect the LFO to both VCOs throught a resistor, then use a common on-off-on switch, extreme pins conected to VCO mod inputs after de resistor, and middle pin connected to ground. So when the switch is in the middle both VCOs have the LFO modulation, when you move the switch to one side, the input goes to ground and that VCO will have no modulation.

_________________
Sebo
---------------------------------------
My Music:
www.cosaquitosenglobo.com.ar
www.myspace.com/cosaquitosenglobo
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Thu Oct 31, 2013 12:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Sebo.

You got me confused.. Confused
Any pic to follow your description?

Cheers

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
Sebo



Joined: Apr 27, 2007
Posts: 538
Location: Argentina

PostPosted: Thu Oct 31, 2013 1:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

Something like this:


VCO Modulation.png
 Description:
 Filesize:  3.63 KB
 Viewed:  2036 Time(s)

VCO Modulation.png



_________________
Sebo
---------------------------------------
My Music:
www.cosaquitosenglobo.com.ar
www.myspace.com/cosaquitosenglobo
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Thu Oct 31, 2013 3:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the scheme Sebo!

As I understand it's not an DPDT switch?
What would be the appropriate values of R1,2,3,4? 1k for each one will be ok?
Last question...
I see what you mean by center position will be both vco's.
But if I'm not mistaken when the switch position will be up for example one path will be passing smoothly, the second path will short with ground but part of it wouldn't go to the vco? I'm asking cause eventually I see it's connected to the vco through a resistor but still connected.

_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
Sebo



Joined: Apr 27, 2007
Posts: 538
Location: Argentina

PostPosted: Thu Oct 31, 2013 4:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

The switch is a common on-off-on switch.
The values for R1, R2, R3 & R4 depends on the value of the input resistor of the VCO CV summing network. Usually this resistor is 100K. You have to remove the original resitor and use R3/R4 instead. In that case a good value will be 51K for all resistors. If you don't want to remove the resistor on the VCO, ommit R3 & R4 and try a small value for R1 & R2, something like 10K will work (I think), but the modulation deep will be a little less than normal...

_________________
Sebo
---------------------------------------
My Music:
www.cosaquitosenglobo.com.ar
www.myspace.com/cosaquitosenglobo
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Thu Oct 31, 2013 11:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok, now after sleeping all make sence to me.

Yes, I'll remove the 100k from the vco's.
The only thing I'm nor sure about is how/where to connect the 100k amount pot.
I think I'll put it from the LFO out before going to the switch.
like the attached pic, what do you think?

Thanks Sebo.


vco_modulation_162.png
 Description:
 Filesize:  4.86 KB
 Viewed:  1923 Time(s)

vco_modulation_162.png



_________________
http://www.myspace.com/mgmtrance
Back to top
View user's profile Send private message
Sebo



Joined: Apr 27, 2007
Posts: 538
Location: Argentina

PostPosted: Fri Nov 01, 2013 10:50 am    Post subject: Reply with quote  Mark this post and the followings unread

That's right.
_________________
Sebo
---------------------------------------
My Music:
www.cosaquitosenglobo.com.ar
www.myspace.com/cosaquitosenglobo
Back to top
View user's profile Send private message
isak



Joined: Dec 13, 2009
Posts: 696
Location: Israel
Audio files: 18

PostPosted: Fri Nov 01, 2013 12:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

Cheers man Smile
_________________
http://www.myspace.com/mgmtrance
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 [24 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