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Need help with design.
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isak



Joined: Dec 13, 2009
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PostPosted: Thu Jan 17, 2013 1:51 am    Post subject: Need help with design. Reply with quote  Mark this post and the followings unread

Hi guys.

i'm in the prosses of building a synth, not mdular, semi modular.
im having a truble finding a way to control the 3 vco's cv's simulteneusly.
i will want to use 1 pot cv for all 3 vco's, is there any way to do it properly?
i know i can use a dual pot but it will give me to control only 2 vco's not 3.
is there any triple pot out there or any other solution?
if there isnt a good way i will have to pass 1 vco and i really dont want to do that.

the panel design is attched.

cheers,
Isak E.


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isak



Joined: Dec 13, 2009
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PostPosted: Thu Jan 17, 2013 3:24 am    Post subject: Reply with quote  Mark this post and the followings unread

I found a triple pot but not the value i need.
I found a 50k linear.
The question is...
In the vco design The pot is 100k and in series with 100k resistor.
Can I make the triple 50k pot in series with 150k resistor?
BTW the vco is Andy's Ody vco.
http://www.ebay.com/itm/4-Panel-PCB-Mini-Triple-Deck-B-50k-Potentiometer-P004-/220516287227?pt=LH_DefaultDomain_0&hash=item3357cb82fb

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Osal



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PostPosted: Thu Jan 17, 2013 3:58 am    Post subject: Reply with quote  Mark this post and the followings unread

The oscillators are CV, so you can control the three oscillators with a single potentiometer.
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isak



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PostPosted: Thu Jan 17, 2013 4:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Really?
The pot I'm talking about is the cv input amount of the vco.
Are you sure that 1 pot will be ok as cv input for all 3 vco's?
Can you explain a bit more please?

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syntherjack



Joined: Oct 29, 2012
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PostPosted: Thu Jan 17, 2013 5:22 am    Post subject: Reply with quote  Mark this post and the followings unread

Hallo,
i don't know how your VCO CV input circuit looks like, but there is some possibility, that with just one pot for 3 CV the VCO's will interfere with each other. But you can always add op-amp buffer before each CV input, then drive all op-amp input from one CV source. I think it should work.
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isak



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PostPosted: Thu Jan 17, 2013 6:01 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks.

did you mean something like the attached scheme?
BTW this is the VCO..
http://electro-music.com/forum/phpbb-files/arp_odyssey_vco_layout_287.pdf


3 VCO's CV in.png
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syntherjack



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PostPosted: Thu Jan 17, 2013 6:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes, this is exactly what i mean.

http://www.arpodyssey.com/schematics/ody_32.gif

There you have 2 VCOs with connected CV inputs. Some are have just resistors, some diodes. So op-amp in not nesessary.
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isak



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PostPosted: Thu Jan 17, 2013 7:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you!
Smile

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syntherjack



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PostPosted: Thu Jan 17, 2013 7:43 am    Post subject: Reply with quote  Mark this post and the followings unread

No problem!

BTW
Nice goa there Smile
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isak



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PostPosted: Thu Jan 17, 2013 8:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks Smile

Didn't do music for a long time now.
after our debut album we didn't do much.
Hope to get back to music soon, I miss that.
Day job is killing me.

Cheers man,
Isak E.

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