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
Buchla VCO
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
Page 7 of 7 [163 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, 3, 4, 5, 6, 7
Author Message
Snaper



Joined: Feb 28, 2014
Posts: 217
Location: Hungary

PostPosted: Thu Aug 14, 2014 3:43 am    Post subject: Reply with quote  Mark this post and the followings unread

vladosh wrote:
Snaper you can use SSM2220 in the v/oct expo converter and use matched 2N3904 for the other as it's in the original Mark Verbos pdf somewhere on this thread if it isn't removed just gotta watch for the pinout ,thanks L1 for sharing the layout ,it is a great VCO ,i wonder what is the best choice for initial freq pot ,my 258 sounds great to me but the init freq pot can act bit weird when moving from zero ,and soldering those SMD isn't much of big deal ,they are really tiny , but it is actually easy once you try few times

Thanks for the info.
Can I use matched 3904 in both places with a tempco?
For me V/Oct tracking isnt that important :S
Back to top
View user's profile Send private message
vladosh



Joined: Aug 02, 2010
Posts: 659
Location: macedonia
Audio files: 46

PostPosted: Thu Aug 14, 2014 2:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

you can use 2N3906 for the other as it's a PNP ,but i'm not an expert really ,well matched transistors are well matched it's up to how good is your DMM and if you've made the Moog matching circuit or other and making it precise ,if you couple them thermally and all that ,i think it's not only about v/oct tracking.. match 2 x 2N3906 and try it ,i sourced those SMD somehow
cheers

_________________
http://synthacks.blogspot.com/ шематикс
Back to top
View user's profile Send private message
Snaper



Joined: Feb 28, 2014
Posts: 217
Location: Hungary

PostPosted: Mon Oct 20, 2014 1:18 am    Post subject: Reply with quote  Mark this post and the followings unread

Did somebody built this?
I think I've wired wrong the switch...
No sound...just kind of "buzz", hum...and...weird...but it seems that I can receive local AM radios with this :S
Back to top
View user's profile Send private message
Snaper



Joined: Feb 28, 2014
Posts: 217
Location: Hungary

PostPosted: Mon Dec 15, 2014 10:07 am    Post subject: Reply with quote  Mark this post and the followings unread

My last silly question.
Is it possible to do a mod to avoid the switch?
I mean, Im ok with one waveform, but I think the cause of my not working modules are those damn switches. Hate them:)
Back to top
View user's profile Send private message
thermionicjunky



Joined: Dec 07, 2006
Posts: 90
Location: san francisco

PostPosted: Tue Dec 16, 2014 8:09 am    Post subject: Reply with quote  Mark this post and the followings unread

Snaper wrote:
My last silly question.
Is it possible to do a mod to avoid the switch?
I mean, Im ok with one waveform, but I think the cause of my not working modules are those damn switches. Hate them:)


The switch is a mod. Simply install either the resistor values listed for saw or square in the schematic. And of course, infinite resistance means that no resistor is installed.
Back to top
View user's profile Send private message
J3RK



Joined: Jun 05, 2006
Posts: 123
Location: Seattle

PostPosted: Fri Dec 19, 2014 9:55 am    Post subject: Reply with quote  Mark this post and the followings unread

I agree 100%. Ditch the switch. It's a nice idea, but the execution is very unreliable. Lifting resistor ends, and wiring a 3P switch... IMO it's not worth it. If you want both square and saw versions, I'd say it's easier to build both, one per PCB.
Back to top
View user's profile Send private message
Snaper



Joined: Feb 28, 2014
Posts: 217
Location: Hungary

PostPosted: Sun Dec 21, 2014 9:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

J3RK wrote:
I agree 100%. Ditch the switch. It's a nice idea, but the execution is very unreliable. Lifting resistor ends, and wiring a 3P switch... IMO it's not worth it. If you want both square and saw versions, I'd say it's easier to build both, one per PCB.

I see. I think I should buy 2 of your pcbs instead.
Have you some spare?
Back to top
View user's profile Send private message
J3RK



Joined: Jun 05, 2006
Posts: 123
Location: Seattle

PostPosted: Mon Dec 22, 2014 2:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

Snaper wrote:
J3RK wrote:
I agree 100%. Ditch the switch. It's a nice idea, but the execution is very unreliable. Lifting resistor ends, and wiring a 3P switch... IMO it's not worth it. If you want both square and saw versions, I'd say it's easier to build both, one per PCB.

I see. I think I should buy 2 of your pcbs instead.
Have you some spare?


Unfortunately I don't stock the 258J anymore. I believe Synthcube and Thonk should have some. (I send these to them every so often.) The reason for that is that I did the UltraFade VCO as a successor. It refines and fixes things, as well as provides more features. It's also a lot easier to build and wire. There's a thread on Muff's in the DIY forum, if you'd like to see more details on it.

FYI: In case my comment wasn't clear, my 258J boards still need to be modded in the same way if you want to add that waveform select switch. It still requires lifting the resistors, and using a 3 pole switch.

The UltraFade uses a different crossfade circuit, and only uses a simple SPDT switch for selecting the faded waveform.
Back to top
View user's profile Send private message
akrearke



Joined: Sep 08, 2008
Posts: 53
Location: US

PostPosted: Sat Mar 14, 2015 7:40 am    Post subject: Reply with quote  Mark this post and the followings unread

does anyone have any idea on a low frequency setting for this vco? possibly increasing the .0047 uf capacitor in the core?
Back to top
View user's profile Send private message
m.o



Joined: Jul 05, 2014
Posts: 44
Location: Sweden

PostPosted: Sun Mar 15, 2015 9:16 am    Post subject: Reply with quote  Mark this post and the followings unread

akrearke wrote:
does anyone have any idea on a low frequency setting for this vco? possibly increasing the .0047 uf capacitor in the core?


Yeah, that would seem like the first and best approach.
Possibly you could start messing with the expo converter currents, maybe increase the 1.5M resistor in the lower left beside the 3140...
Back to top
View user's profile Send private message
J3RK



Joined: Jun 05, 2006
Posts: 123
Location: Seattle

PostPosted: Mon Mar 16, 2015 3:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

You should have no problem doing this with a capacitor. What I would do is connect one lead of a 100nF cap to one lead of the 4.7nF cap. Then use an SPST switch between the other two ends. That way you can switch the low frequency cap in and out.

When they are connected in parallel the slower speed will occur. When you disconnect the 100nF cap, only the 4.7nF will be used.

It's not terribly critical which type of cap you use for the LFO cap. I'd still use something fairly stable though. MLCC, Styrene, Polypropylene or the like. (though even a standard ceramic or Polyester will be fine.)
Back to top
View user's profile Send private message
Karlisss



Joined: Apr 20, 2015
Posts: 25
Location: Latvia (EU)

PostPosted: Sat Aug 29, 2015 12:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

Can it run from 12v dual?
Back to top
View user's profile Send private message
vladosh



Joined: Aug 02, 2010
Posts: 659
Location: macedonia
Audio files: 46

PostPosted: Wed Jul 31, 2019 11:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

i just built this yesterday and can't get it to run ,i've built maybe 10 of these vco's but the last two times i tried i failed ,i get -12V at the output ,anyone have idea what is voltage at pin 5 of CA3080 ? or some other tips ?
Thanks
Vladko

_________________
http://synthacks.blogspot.com/ шематикс
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 7 of 7 [163 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2, 3, 4, 5, 6, 7
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