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Tasmanian Alkaloid
Joined: Jun 29, 2008 Posts: 116 Location: Isle De Mort
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Posted: Mon Mar 16, 2009 2:02 am Post subject:
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What value pots did you guys use for this? I find the schematic a bit cryptic, but maybe i'm not reading it right. |
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akrearke
Joined: Sep 08, 2008 Posts: 53 Location: US
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Posted: Tue Mar 31, 2009 11:33 pm Post subject:
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Just finished two boards. one for saw, one for square. I'm using these as development boards for further study of the wave shaping circuit. the pin placement for the ssm2220 is incorrect. there are good expo circuits out there for sure... the potentiometer values are on the original (buchla brand) schematic. |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Posted: Wed Apr 01, 2009 1:32 am Post subject:
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akrearke wrote: | Just finished two boards. one for saw, one for square. I'm using these as development boards for further study of the wave shaping circuit. the pin placement for the ssm2220 is incorrect. there are good expo circuits out there for sure... the potentiometer values are on the original (buchla brand) schematic. |
Great news! I'm gonna be building a few of these myself soon; Could you post some pictures of your build? |
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akrearke
Joined: Sep 08, 2008 Posts: 53 Location: US
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Posted: Wed Apr 01, 2009 7:38 am Post subject:
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Still waiting to post pics of the TKB stuff, don't own a digi-cam. will try soon to post pictures |
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forbin
Joined: Jan 29, 2009 Posts: 120 Location: Fremantle, Australia
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Posted: Thu Jun 04, 2009 9:02 pm Post subject:
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Well it's been a bit of a saga, which now I'm at the end of it all seems a bit unnecessary. I was probably thrown a bit by some of my SPICE modelling which took me off at a tangent. Anyway sourced some 2N4339's -- as recommended by Don -- and it now flies!
Thanks again to Mark Verbos for the layout!
For photos and comparison see my blog: http://forbinthesynthesizer.blogspot.com/ |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Posted: Thu Jun 04, 2009 10:21 pm Post subject:
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forbin wrote: | Anyway sourced some 2N4339's -- as recommended by Don -- and it now flies!
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Had you tried the 3819 first--with less success? Just curious. As usual, inspiring, informative website; Anxious to see how your SOU Romeo-Board 4 comes out! |
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forbin
Joined: Jan 29, 2009 Posts: 120 Location: Fremantle, Australia
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Posted: Thu Jun 04, 2009 10:43 pm Post subject:
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The 3819 problem was that the behavior of the sine generator "flips over" for want of some real understanding of what is going on. Some "interesting" bias issues i think. This results in quite a nice sinewave shape but at a greatly reduced amplitude. I became more preoccupied with the shape and less so with the amplitude. When you come to mixing in the flat topped sawtooth it produced rubbish really.
SoU board #1 (my 3rd board) is running very well and i am now embarking on the last one -- waiting from some LF398's -- I am also working on a board 5 which is an AVR digital/analog noise source and a Grey filter |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Posted: Thu Jun 04, 2009 10:57 pm Post subject:
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forbin wrote: | The 3819 problem was that the behavior of the sine generator "flips over" for want of some real understanding of what is going on. |
Good to know, thanks. Is there a reliable source for the 2N4339 that you can mention?
forbin wrote: |
i am now embarking on the last one -- waiting from some LF398's |
I believe this is the one I'm particularly interested to hear about, board#4. Mostly because I wasn't able to get mine working! |
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forbin
Joined: Jan 29, 2009 Posts: 120 Location: Fremantle, Australia
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Posted: Fri Jun 05, 2009 1:52 am Post subject:
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I bought mine from Farnell, in the US they are Newark I think. They were fairly expensive though... but since it was only two parts and it was for my sanity! I did find a document that said that the J201 is exactly the same just a plastic package instead of a metal one. They were cheaper but not available
I must admit to having a number of S&H and was tempted to not bother with #4 of SoU but for completeness why not... |
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Posted: Fri Jun 05, 2009 12:55 pm Post subject:
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forbin wrote: | I bought mine from Farnell, in the US they are Newark I think. |
Thanks, I´ll take a look for them.
There is a 2N4339-ES available from Mouser also, if anyone else is looking.
forbin wrote: |
I must admit to having a number of S&H and was tempted to not bother with #4 of SoU but for completeness why not... |
Understandable, but there´s also the VC Lag and switching pulse outputs. Seems pretty neat to me. I wish I could get back to work on mine; am very far away from projects presently. |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Posted: Mon Jun 08, 2009 3:42 pm Post subject:
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Peake:
Have you made progress with your 258b clone? I was reading about it with much interest for long while. Last edited by ericcoleridge on Mon Sep 07, 2009 2:45 am; edited 2 times in total |
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TekniK
Joined: Aug 10, 2008 Posts: 1059
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Posted: Tue Jun 09, 2009 2:07 am Post subject:
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Peake wrote: | http://www.flickr.com/photos/11165691@N03/1459599639/ |
thanks! |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Fri Jun 12, 2009 3:09 pm Post subject:
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ericcoleridge wrote: | Have you made progress with your 258b clone? I was reading about it with much interest for long while. |
All it requires is a bit of time and effort (currently not possible). Remember, Don did not give me permission to publish the PCB artwork.
I have a Moog 901a/b direct PCB trace copy artwork ready to post, excepting wiring diagrams and the technical work required to select the critical transistors; however, like the Buchla, it's in storage and not easily avaialble! Shrug.. _________________ We are selling emotions, there are no emotions in a grid. -mwagener
"IC 741. Sometimes you don't want fidelity." -Small Bear Electronics Catalog |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Posted: Mon Sep 07, 2009 2:44 am Post subject:
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Tasmanian Alkaloid wrote: | What value pots did you guys use for this? I find the schematic a bit cryptic, but maybe i'm not reading it right. |
Based on the two online schematics (for the 258, and 258c), I've found the following pot values:
CV +/- : 10k
FM Input: 50k Audio
Waveshape Control: 10k
Frequency Control: 10k
However, I noticed that there are only pads for 4 pots on the Verbos layout, but 5 pots on the original module. Does anyone know what the other pot does? It's between 'FM' and 'Waveshape' and it's a +/- input. I thought at first it could be a +/- index for the FM? But looking at the schematic (top left hand corner), it seems to be a second +/- CV input. Am I looking at this right?
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Mon Sep 07, 2009 5:11 am Post subject:
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I think you're right, it looks like a second CV in.
So it's:
Exp CV in
FM in
Exp CV in
Waveshape in _________________ http://www.thehumancomparator.net/ |
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Tasmanian Alkaloid
Joined: Jun 29, 2008 Posts: 116 Location: Isle De Mort
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Posted: Mon Sep 07, 2009 7:41 am Post subject:
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ericcoleridge wrote: | Tasmanian Alkaloid wrote: | What value pots did you guys use for this? I find the schematic a bit cryptic, but maybe i'm not reading it right. |
Based on the two online schematics (for the 258, and 258c), I've found the following pot values:
CV +/- : 10k
FM Input: 50k Audio
Waveshape Control: 10k
Frequency Control: 10k
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Thanks
I also spoke to forbin, & he told me he used 100k Linear pots for all of them, & that they worked ok. I still haven't gotten round to building mine yet, but i have the parts now...just gotta focus & get it done
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mono-poly
Joined: Jul 07, 2004 Posts: 937 Location: Rotterdam, Netherlands
Audio files: 2
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Posted: Mon Sep 07, 2009 3:54 pm Post subject:
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zthee wrote: | I think you're right, it looks like a second CV in.
So it's:
Exp CV in
FM in
Exp CV in
Waveshape in |
Bingo! |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Mon Sep 07, 2009 11:23 pm Post subject:
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Peake wrote: | http://www.flickr.com/photos/11165691@N03/1459599639/ |
Is that a real panel, or you made it yourself? _________________ http://www.thehumancomparator.net/ |
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forbin
Joined: Jan 29, 2009 Posts: 120 Location: Fremantle, Australia
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Posted: Mon Sep 07, 2009 11:47 pm Post subject:
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To try and help I have put some more pictures on my Blog site... The whole VCO project has started to grow a second head -- since i am not really that interested in creating a perfect clone I have made a second wave shaper that is fed from the same control voltage and I have also picked out the triangle signal. My panel no has fine/coarse frequency, two frequency modulations (linear and log) with CV amounts, and the waveshape control with a CV amount (+ and -) and an offset and the three outputs, triangle, saw and square. I have made a small PCB that buffers the three outputs and also has a summer and gain and offset control for the waveshaper. Currently waiting for more cliff sockets to finish the panel!
Blog: http://forbinthesynthesizer.blogspot.com/ |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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