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 
 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
Analog Switch Matrix questions
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [4 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
macumbista



Joined: Sep 12, 2007
Posts: 360
Location: berlin
Audio files: 3

PostPosted: Mon Aug 26, 2013 3:55 pm    Post subject: Analog Switch Matrix questions Reply with quote  Mark this post and the followings unread

I'm trying to wrap my head around the Analog Switch Matrix schematic:

http://www.cgs.synth.net/modules/cgs55_asm.html

I understand the the 4066 CMOS switch cannot handle negative voltages, and that is why there are reverse-biased diodes before and after it. However, wouldn't that remove the negative component of any bipolar signal you sent through the module?

I am looking for the place where the signal would get floated on a virtual ground, as in single-supply guitar pedal electronics for example, but I'm just not seeing it.

How does a bipolar signal pass through this module unaffected?

Thanks and best! D.

_________________
Esoteric drones and nonlinear distortion
Custom/handmade experimental instruments
macumbista.net
Back to top
View user's profile Send private message
PHOBoS



Joined: Jan 14, 2010
Posts: 1731
Location: Moon Base
Audio files: 346

PostPosted: Mon Aug 26, 2013 5:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm not seeing it either,. looks indeed like it only works with positive signals.
_________________
"My perf, it's full of holes!"
http://phobos.000space.com/ http://www.acidtrash.com/ Stickney Synthyards
Back to top
View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger MSN Messenger
macumbista



Joined: Sep 12, 2007
Posts: 360
Location: berlin
Audio files: 3

PostPosted: Mon Aug 26, 2013 5:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

SOLVED!

Ken Stone wrote:

Quote:
The diodes only have any effect when the switches are open, so they can be
ignored.
When the switches are closed, both sides of the switch are connected to the
summing node, or "virtual ground" of the op-amp circuit, thus stay at zero
volts the whole time. From that point it is just a matter of understanding
the basic inverting op-amp summer circuit.

_________________
Esoteric drones and nonlinear distortion
Custom/handmade experimental instruments
macumbista.net
Back to top
View user's profile Send private message
PHOBoS



Joined: Jan 14, 2010
Posts: 1731
Location: Moon Base
Audio files: 346

PostPosted: Mon Aug 26, 2013 6:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

aha, I was allready wondering if the fact that the switch was placed between
the resistor and the opamp (instead of before the resistor) might have anything
to do with it. yeah that makes sense Very Happy (Now I need to remember it for future circuits)

_________________
"My perf, it's full of holes!"
http://phobos.000space.com/ http://www.acidtrash.com/ Stickney Synthyards
Back to top
View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger MSN Messenger
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [4 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 » Ken Stone designs - CGS
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