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 Forum index » DIY Hardware and Software
Buchla 218 VC-able Portamento - Works!
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vtl5c3



Joined: Sep 08, 2006
Posts: 423
Location: PDX
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PostPosted: Thu Jun 28, 2007 9:57 am    Post subject: Buchla 218 VC-able Portamento - Works! Reply with quote  Mark this post and the followings unread

Last night I finally tested the slew circuit that I cloned from the Buchla 218 keyboard. I'm happy to say that it works. I've posted the schematic and a couple of sound samples below. I may have to do a bit of fine tuning... if nothing else I will try smaller cap values, since it's pretty easy to get way too much portamento going.

Update: I've uploaded the PCB layout, for those who like to roll their own.


Buchla_218_Portamento.jpg
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Buchla_218_Portamento.jpg



buchla_VTL_slew_PCB.jpg
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PCB Layout. Works!
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buchla_VTL_slew_PCB.jpg



218_slew_01.mp3
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218_Slew_02.mp3
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buchla_218_Slew_parts.pdf
 Description:
Parts layout. Corrected diode part number.

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 Filename:  buchla_218_Slew_parts.pdf
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Last edited by vtl5c3 on Tue Dec 30, 2008 11:19 am; edited 5 times in total
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StephenGiles



Joined: Apr 17, 2006
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PostPosted: Thu Jun 28, 2007 10:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Interesting - I was waiting for Jeff Beck to crash in! Have you heard him make similar sounds!
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StephenGiles



Joined: Apr 17, 2006
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PostPosted: Thu Jun 28, 2007 10:59 am    Post subject: Reply with quote  Mark this post and the followings unread

Here's a sample of Jeff Beck doing just that
http://www.4shared.com/file/18815193/15b17a7/JBeck.html

His fingers, a whammy bar and a Rat distortion!
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bubblechamber



Joined: Nov 04, 2006
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PostPosted: Thu Jun 28, 2007 10:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

thanks for posting
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krisp14u



Joined: Nov 11, 2006
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PostPosted: Fri Jun 29, 2007 8:32 am    Post subject: Reply with quote  Mark this post and the followings unread

Cheers for that vtl5c3 I will have a go at this 1 over the weekend

paul D

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StephenGiles



Joined: Apr 17, 2006
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PostPosted: Sat Jun 30, 2007 5:19 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm not quite sure if I needed to have bothered (subjunctivo!) with the Jeff Beck sample - a lot of synth players would give their right arm to play like that!!
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Quad



Joined: Dec 30, 2006
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Location: Stockholm, Sweden

PostPosted: Sat Jun 30, 2007 8:42 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for posting!

What is the difference between Ground and N Ground? and what is L1 & L2?

thanks!
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vtl5c3



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PostPosted: Sat Jun 30, 2007 8:53 am    Post subject: Reply with quote  Mark this post and the followings unread

Quad wrote:
Thanks for posting!

What is the difference between Ground and N Ground? and what is L1 & L2?

thanks!


Noisy ground and regular (quiet?) ground. Buchla often had separate grounds in his modules. As you can see they join together on this PCB. No need to worry about the differences. L1 & L2 are ferrite beads, same as you find on most prefab DIY PCBs these days. You can use low value resistors or jumpers if you don't have ferrite beads.

Romeo
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Fernando



Joined: Dec 30, 2006
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PostPosted: Tue Jul 10, 2007 7:30 am    Post subject: Reply with quote  Mark this post and the followings unread

I missed the thread.

wow, thank you so much!
(actually the "wow" was a "fantastico" before being slewed)



Is the 4.7uF capacitor that you are refering to?

maybe is the control of the LED's vactrol what should be finetuned...?


_
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Dave Manley



Joined: Sep 03, 2007
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Location: North Bay, California

PostPosted: Sun May 04, 2008 9:25 am    Post subject: Reply with quote  Mark this post and the followings unread

I was looking for the 218 schematics yeseterday and couldn't find them in the usual places. Are they online somewhere?

-Dave

P.S. Is there anything Buchla couldn't (wouldn't?) do with a vactrol? Very Happy
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cbm



Joined: Oct 25, 2005
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PostPosted: Sun May 04, 2008 1:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

Dave Manley wrote:
Is there anything Buchla couldn't (wouldn't?) do with a vactrol? Very Happy


Sort of like Serge and the LM3900.

-C

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vtl5c3



Joined: Sep 08, 2006
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PostPosted: Fri May 09, 2008 10:59 am    Post subject: Reply with quote  Mark this post and the followings unread

Did you need the entire 218 schematic set? I don't think it's online, but I have them. Could have sworn I got them off the web at some point.

R.

Dave Manley wrote:
I was looking for the 218 schematics yeseterday and couldn't find them in the usual places. Are they online somewhere?

-Dave

P.S. Is there anything Buchla couldn't (wouldn't?) do with a vactrol? Very Happy
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cbm



Joined: Oct 25, 2005
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PostPosted: Fri May 09, 2008 12:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quite a few older Buchla schemos:
http://rubidium.dyndns.org/~magnus/synths/companies/buchla/

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Dave Manley



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PostPosted: Sat May 10, 2008 12:12 am    Post subject: Reply with quote  Mark this post and the followings unread

I was studying the Easel and the 218 is a key part of it. The 216 and 217 are online at Magnus' site, but the 218 is absent. It would be a good addition to his pages if available.

How many pages total are there in the 218?
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CJ Miller



Joined: Jan 07, 2007
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PostPosted: Tue May 27, 2008 1:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool... I was just looking over slew/portamento ideas, and I was surprised how few are VC-able.

In the schematic, it calls for a 6V Zener diode. But on your PCB diagram it says 1N5224. Isn't this a 2.8V Zener? What Zener did you use here? I don't know how crucial it is, as I have neither anyway. I'm a vactrol n00b and I don't want to fry them.

Nice efforts studying Buchla's work! Most of his stuff makes my head spin.
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vtl5c3



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PostPosted: Tue May 27, 2008 8:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Good question. I'll have to check my work when I get home. You're correct that the 1N5224 is a 2.8 Zener. It should read 1N5233. Thanks for pointing it out.

R.

CJ Miller wrote:
Cool... I was just looking over slew/portamento ideas, and I was surprised how few are VC-able.

In the schematic, it calls for a 6V Zener diode. But on your PCB diagram it says 1N5224. Isn't this a 2.8V Zener? What Zener did you use here? I don't know how crucial it is, as I have neither anyway. I'm a vactrol n00b and I don't want to fry them.

Nice efforts studying Buchla's work! Most of his stuff makes my head spin.
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haxster



Joined: Feb 01, 2006
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PostPosted: Sun Nov 16, 2008 12:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Is the type of vactrol used critical? Would a VTL5C4 be okay to use. I am new to vactrols.
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doctorvague



Joined: Mar 14, 2007
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PostPosted: Sun Nov 16, 2008 1:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

The VTL5C4 would be slower than the usual VTL5C3 that Buchla uses. It's not spec'd here but I'm assuming it is a VTL5C3 in this circuit. The 'slower' would just be response to control changes, not the portamento itself. IOW, if you wanted quick turn-on and turn-off of portamento via control voltages it will have more lag time, especially the turning off or quick turning down of the portamento. Kinda like portamento'd portamento. Shocked

Cheers
Phil

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vtl5c3



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PostPosted: Sun Nov 16, 2008 3:25 pm    Post subject: Schematics Reply with quote  Mark this post and the followings unread

Forgot that I was gonna post them, but here they are.


Buchla218-1.jpg
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218 Schem Page 1
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Buchla218-1.jpg



Buchla218-2.jpg
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Buchla 218 Page 2 Schem
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Buchla218-2.jpg



Buchla218-3.jpg
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Buchla 218 Board Part Placement
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Buchla218-3.jpg


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probablyjoel



Joined: Aug 31, 2008
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PostPosted: Sun Dec 07, 2008 9:47 am    Post subject: dumb newbie question... Reply with quote  Mark this post and the followings unread

What type of offboard components are you using for the control inputs? Just standard 1/4" jacks?
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vtl5c3



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PostPosted: Sun Dec 07, 2008 10:07 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm using 1/8th inch jacks. Nothing fancy.
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probablyjoel



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PostPosted: Sun Dec 07, 2008 10:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you! One more question...I'm not so familiar with the buchla... how do the control inputs differ from the input? If i use it for my 4017 step sequencer, would it work through the normal input or through the control input?
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vtl5c3



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PostPosted: Sun Dec 07, 2008 11:39 am    Post subject: Reply with quote  Mark this post and the followings unread

Whatever CVs you'll be processing go into the normal input. The CV input controls how much portamento is applied to the processed voltage.

probablyjoel wrote:
Thank you! One more question...I'm not so familiar with the buchla... how do the control inputs differ from the input? If i use it for my 4017 step sequencer, would it work through the normal input or through the control input?
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probablyjoel



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PostPosted: Sun Dec 07, 2008 2:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

So i would need another CV control to control the level of portamento? What types work best as controllers? Sorry if this is super obvious... I'm still a newbie:).
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vtl5c3



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PostPosted: Sun Dec 07, 2008 2:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

You can use the manual control to set a portamento amount, but the value only changes when you turn the knob. To CV control it, run an LFO into it, have a second analog sequencer control it, or even aftertouch from a keyboard... really any CV source will work.

probablyjoel wrote:
So i would need another CV control to control the level of portamento? What types work best as controllers? Sorry if this is super obvious... I'm still a newbie:).
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