electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links
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 » Thomas Henry designs
VCO-1 on +/- 12V?
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [2 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
mikeb



Joined: Nov 20, 2006
Posts: 59
Location: The Automotive Capital of Canada

PostPosted: Tue Jul 10, 2012 1:27 pm    Post subject: VCO-1 on +/- 12V? Reply with quote  Mark this post and the followings unread

Hey all,
Just wondering if anyone is successfully using Thomas' VCO-1 on a 12V supply?
I know R23 and R43 change, is there any other changes that anyone would suggest making?

Mike
Back to top
View user's profile Send private message
Osal



Joined: Aug 16, 2011
Posts: 147
Location: Here

PostPosted: Thu Jul 12, 2012 1:22 am    Post subject: Reply with quote  Mark this post and the followings unread

Time ago I wrote this:

The basic idea is to look for current and voltage references, offsets and amplitudes.
The number references of the components refer to the schematics of the VCO1 that you can find here: http://www.birthofasynth.com/Thomas_Henry/Pages/VCO-1.html

R43 provides a current reference. You change it with a simple rule of three, so if for 15V is 1.5M for 12V is 1.2M

The coarse and fine controls will see reduced their span.
Look that with a +15V/-15V supply, the coarse control does span 30 octaves. So maybe in this case you don't need to change it. With a +12/-12V supply it does span 24 octaves.
However, if you desire decrease or increase the span, it is achieved increasing or decreasing R28.
About the fine control, it could be useful to change it. For example for a +15/-15V supply R46=3M, it does span one octave. So, for a +12/-12V R46=2.4, it does span also one octave.

This could be useful useful for all expo converters... like the one in the VCF1

.....
At this point I bread-boarded the VCO1 core and its waveshapers.
.....

I measured the triangle output and the amplitude was about 8 p-p , I achieved it to be close to 10Vp-p with:
R22=24K
R13=3.9K
R30=110K

Then, for the sine output I achieved 10V p-p with:
R18=14K
R19=14K

For the pulse output I expected also a smaller output, since the comparator goes from one rail to the other.
I achieved 10V p-p and 1KΩ of standard output impedance with:
R12=2K
R7=2K

Finally, we have R41. It decides the pulse width span of the potentiometer.
In my breadboard, I noticed that with R41=265K, the pulse goes from approx. 5% to 95% . Other folks could prefer other configuration.

Oscar.

_________________
electronic-sea.net
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [2 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 » Thomas Henry designs
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


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use