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
  Rob Adventures in Sound
Please visit the chat
 Forum index » DIY Hardware and Software » Circuit Bending
"Oscillators" for circuit bent machines?
Post new topic   Reply to topic Moderators: dnny, v-un-v
Page 1 of 1 [3 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
Rolbista



Joined: Nov 17, 2012
Posts: 20
Location: Poland

PostPosted: Sun Feb 03, 2013 1:43 pm    Post subject: "Oscillators" for circuit bent machines? Reply with quote  Mark this post and the followings unread

Ok, so here's a concept: take the most sinusoidal waveform of your bent keyboard and filter it a little to remove harmonics. Step 2: convert it to a square wave with a Schmitt trigger - here's your first waveform. Step 3: use a 4040 to get one and two octaves below. Step 3: either route the received square wave of chosen octave straight to the output or feed it into this: http://electro-music.com/forum/post-244968.html to get a sawtooth. Build 3 of such units and voila! you have 3 "VCO" on your cheap Casio keyboard! Ok, does that even make sense, I've never seen anyone do it, maybe there's a reason? And what would be the right Schmitt setup to get it to work? I used a TL072 set up as a non-inverting trigger from wikipedia with two 25k trimpots, but no matter how i set the trimpots, it doesn't output any square. Power: +/-5V, I'm viewing the signal on a scope. The signal from the Casio is around 1Vpp.
Back to top
View user's profile Send private message
JingleJoe



Joined: Nov 10, 2011
Posts: 876
Location: Lancashire, England
Audio files: 14

PostPosted: Tue Feb 19, 2013 8:08 am    Post subject: Reply with quote  Mark this post and the followings unread

Your casio output is too low, add a pre-amplifier, a simple op amp circuit should do. Incase you don't know and for anyone else who doesn't, to make it work from a single rail supply you can bias up your non inverting input to half supply AKA virtual ground.

a circuit you could use:
http://i.cmpnet.com/audiodesignline/2008/03/2vrms_fig4.jpg
(I'd suggect you make the input capacitor above 1uF to avoid filtration effects on low frequencies, it is effectively a high pass filter to remove any existing DC offset)
real ground and virtual ground:
http://lh3.ggpht.com/_gnU30vMbtYg/Tcsp40CovkI/AAAAAAAAAlo/5B6pBJftET8/dual%20ground_thumb.png

Technically it's not 3 vcos because they are all at the same frequency, inr eality 3 vco's would be entirely separate things which can be at individual pitches.
However some complex waveshaping for your simple keyboard does bring it ever closer to being a true synthesizer Smile

_________________
As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"


Green Dungeon Alchemist Laboratories
Back to top
View user's profile Send private message
Rolbista



Joined: Nov 17, 2012
Posts: 20
Location: Poland

PostPosted: Tue Feb 19, 2013 10:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the reply! Yeah, that's why I put "VCO" in quotes Very Happy. So paired with a preamp stage, the circuit you posted in the first link should output a square wave of the same frequency as the input signal? How much should I amplify the signal? Would 5Vpp be fine? I've been thinking about this for a while now, I recently thought about incorporating a fragment of an analog guitar octaver to extract fundamental frequency, but I don't know where that fragment ends. Such "VCO" paired with an LTC1799 pitch bend mod could give me a wide range of possibilities (for a Casio anyway).
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: dnny, v-un-v
Page 1 of 1 [3 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 » Circuit Bending
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
AmbiphonicDSP

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