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 » Developers' Corner
Ultra simple saw LFO?
Post new topic   Reply to topic Moderators: DrJustice
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
Kenneth



Joined: Apr 16, 2009
Posts: 43
Location: Stockholm, Sweden

PostPosted: Mon May 11, 2009 7:42 am    Post subject: Ultra simple saw LFO? Reply with quote  Mark this post and the followings unread

Will this work?

Code:

Shematic:
           ____
5 volt ---|NAND|________.     
       .--|gate|        |---(square)
       |   __________   |
       |--|portamento|--´
       |
       ´---------------------(saw)


As I understand there is a difference between the voltages where the output from the NAND goes from 0 to 1 and from where it goes from 1 to 0. The idea is to use that difference to create a saw LFO (and get a square for free but I need the saw).

The portamento is a knob and a cap that creates a delay in the change of voltage, if this works, what values would i need to get "normal" LFO rates? (like 0.5 to 30 hz or something)
Back to top
View user's profile Send private message
Blue Hell
Site Admin


Joined: Apr 03, 2004
Posts: 20536
Location: The Netherlands, Enschede
Audio files: 147
G2 patch files: 318

PostPosted: Mon May 11, 2009 9:32 am    Post subject: Re: Ultra simple saw LFO? Reply with quote  Mark this post and the followings unread

Kenneth wrote:
As I understand there is a difference between the voltages where the output from the NAND goes from 0 to 1 and from where it goes from 1 to 0.


There would be when you'd use a hysteresis port like the cd4093, or alternatively just use an inverter with schitt trigger on it's input, like the cd40106.

For non schmitt triggered inputs there is not really much difference in the switching levels for upgoing or downgoing edges, it would oscillate on a very high frequency.

Anyway, you just re-invented the relaxation oscillator Cool

As for the timing (in seconds), a rough indication would be the product of R (in Ohms) and C (in Farads), just experiment a bit ... however there will be some issues for very low frequencies, and the wave form wll not be exactly like you'd expect it to be ... but it would work Exclamation

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



Joined: Apr 16, 2009
Posts: 43
Location: Stockholm, Sweden

PostPosted: Mon May 11, 2009 11:11 am    Post subject: Reply with quote  Mark this post and the followings unread

OK, thank's a lot Smile

I just happen to found a dual NAND in an old VCR and I thought it may be useful. I'm trying to put my DIY parts together from scrap parts only, that VCR had two cups full of nice parts...

Well have to look at some old computer cards I got laying around then, to find more useful stuff than my NAND and then go for the experiments Cool
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: DrJustice
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 » Developers' Corner
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