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 
go to the radio page Live at electro-music.com radio 1 Please visit the chat
poster
 Forum index » DIY Hardware and Software
ARP 4027-1 VCO Saw Core
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
Page 2 of 2 [27 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Goto page: Previous 1, 2
Author Message
gdavis



Joined: Feb 27, 2013
Posts: 359
Location: San Diego
Audio files: 1

PostPosted: Wed Jul 09, 2014 1:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

koenpepping wrote:
Hi,

first of all thanks for sharing the vco Smile
I was looking at the BOM and noticed the ST3P switch.

my question is:
what does it do? and where can i find one?

thanks again and already!


It switches the frequency range between audio and LFO. See LF-SWITCH-A,B and C in the schematic.

Pole A changes the frequency CV, pole B switches in another capacitor at what I'm guessing is the core integrator (A and B both result in lower frequency) and pole C switches in a trimmer for the triangle shaper (presumably to improve the triangle shape in LFO mode).

I don't know what sources you have available to you but Mouser seems to have plenty of 3PST switches to choose from. You could also use a 3PDT if that's easier to find, just leave one throw unconnected.

_________________
My synth build blog: http://gndsynth.blogspot.com/
Back to top
View user's profile Send private message
w5cdt



Joined: Dec 31, 2014
Posts: 1
Location: Austin

PostPosted: Wed Dec 31, 2014 1:16 pm    Post subject: ARP 4027-1 LTSpice simulations
Subject description: Simulating the 4027-1 oscillator
Reply with quote  Mark this post and the followings unread

I just put together a 4027-1 VCO simulation in LTSpice. Works good but I did notice that any JFETs will work as long at their VTo is larger than about -2 volts. I also incluced the HF track feedback circuit (as annotated).
See attached schematic and simulation waveforms. This is a good way to see firsthand what waveforms should look like before you build the actual circuit.


4072-1_transient.png
 Description:
 Filesize:  53.89 KB
 Viewed:  322 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

4072-1_transient.png



4072-1_transient_zoomed.png
 Description:
 Filesize:  47 KB
 Viewed:  229 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

4072-1_transient_zoomed.png


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 2 of 2 [27 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2
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


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