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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
Dual MFOS VCO build
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friedo



Joined: Sep 28, 2013
Posts: 7
Location: Brooklyn, NY

PostPosted: Sun Nov 03, 2013 1:38 pm    Post subject: Dual MFOS VCO build Reply with quote  Mark this post and the followings unread

Howdy,

Following on from my last thread about my first experiment in building an MFOS board, here is my latest accomplishment: a fully built dual MFOS VCO module.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

The front panel is my own design, made through Front Panel Express. (They are awesome.) I made a new video documenting the complete build process (including several dumb mistakes I made) and put it up here:

http://www.youtube.com/watch?v=6RGbt6iPLLw

One thing I haven't figured out yet is why the triangle and sine wave appear to be misbehaving. The triangle wave output seems to be generating merely a reversed ramp wave. IIRC, that's supposed to me mixed with the original ramp wave signal and a diode used to filter it into a triangle wave, but that doesn't seem to be working for a reason I can't seem to track down.

Since the sine wave is built from the triangle wave output, that's also messed up. You basically get a half sine wave rather than a complete one. (See the scope shots towards the end of the video.)

I don't particularly need a super-accurate VCO, but it would be nice to figure out what's causing that problem so if you have any advice I'd love to hear it.
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ashleym



Joined: Aug 20, 2009
Posts: 181
Location: uk

PostPosted: Sun Nov 03, 2013 4:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

Good work fella.

I hope you aren't, but in case you are worrying about making mistakes with soldering- we all did/do/and will do!!!

I had a quick look at the video and I will look at the circuits to see if there are any suggestions I might have. My advice will come from a fresh set of eyes rather than any great brain. BTW is it a first to have decent sound on a youtube clip?

One thought I had from looking at your panel is that some of the labelling of the sockets looks cramped. Perhaps you could try a different labelling layout? Something like a column with CV at the top then just a line linking sockets so they all group together visually
CV
O
|
O
|
O

or rows with
SQ Tri Sin Sync
A O O O O
B O O O O
(I am now using symbols rather than words, /\ ~ etc)

From what I see of your design and what I do we use different amounts of labelling......but if you get a but stuck for panel space you can eliminate some labels. For example on this panel as you have already called it a VCO you could get away with just having a label A or B rather than oscillator A as we already know it is an oscillator. Please don't take this as any sort of criticism, I am just giving you my thoughts- hopefully constructive ones.

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friedo



Joined: Sep 28, 2013
Posts: 7
Location: Brooklyn, NY

PostPosted: Sun Nov 03, 2013 7:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for your comments, ashleym. Yep, the labeling is a bit cramped. That was due to my laying everything out in Front Panel Designer, which takes account of the drill holes and labels but makes it easy to forget that every jack is surrounded by a big ol' nut.

My subsequent designs for my VCF and VCA panels have some more breathing room for the jacks. (They also require far fewer jacks which makes that easier.)

The module is also pretty small compared to what most people build for MFOS boards, just 3.5 by 7 inches. (And it's a dual). That's why I decided to put all the jacks at the bottom, to keep the patch cords out of the way.

BTW, I didn't do anything fancy for the audio. Literally just pointed my speaker (half of an old powered computer speaker set) at the camera and made sure I had a quiet room to work in. Cool
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Wed Nov 06, 2013 4:19 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice Job!

I did a dual MFOS a while back - I just did the panel with spray paint and a label machine -
Here it is...
http://www.youtube.com/watch?v=fthnNCiAP08

Gary
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friedo



Joined: Sep 28, 2013
Posts: 7
Location: Brooklyn, NY

PostPosted: Wed Nov 06, 2013 6:23 pm    Post subject: Reply with quote  Mark this post and the followings unread

Very cool! Love those shiny pot knobs. Cool
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Thu Nov 07, 2013 8:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks - I really love the old Black and Silver look.
I'm getting started on a 4U system now, but it feels weird switching to the different aesthetic...

Gary
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Skrog Productions



Joined: Jan 07, 2009
Posts: 1196
Location: Scottish Borders
Audio files: 155

PostPosted: Mon Nov 11, 2013 1:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice panel colours Very Happy

Dave.
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