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 Forum index » Wanted, For Sale, Opportunites and Requests » Parts and Components
ua726
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soundforger



Joined: Jun 24, 2011
Posts: 20
Location: The Netherlands

PostPosted: Thu May 02, 2013 3:49 am    Post subject: ua726
Subject description: Does anyone know know a replacement? or a way around it?
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I want to build a few (Formant) VCO's, but I can't get my hands on UA726's.

Does anyone know a replacement, or a way around it? Can I use matched transistors with a tempco? My knowledge of electronics is limited, so very complicated design modifications of the schematic of the VCO may be a little to much for me, unless you explain it to me as if I were a six-year-old. Confused .
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soundforger



Joined: Jun 24, 2011
Posts: 20
Location: The Netherlands

PostPosted: Thu May 02, 2013 3:51 am    Post subject: Reply with quote  Mark this post and the followings unread

The Formant was published around 1980 when I was 20 or so. Back then I didnt have the money for the project. I do now, provided that the parts I need are available...
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Blue Hell
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Joined: Apr 03, 2004
Posts: 20536
Location: The Netherlands, Enschede
Audio files: 147
G2 patch files: 318

PostPosted: Thu May 02, 2013 1:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ah .. didn't have the money either at that time .. later bought a formant built by someone else .. very cheap at that time ... payed like 200 Euro for it Shocked (although the build quality is not great).

Not knowing the answer I googled a bit ... and now remember that the µa726 was used for heating too.

Technically it should be possible to change it for a matched pair indeed and a tempco would certainly be a good idea then ... best bet probably would be to find similar designs and copy from that a bit.

BTW .. a lot of 741's were used in the Formant, I'd replace those for something more modern .. the Formant is a bit noisy in parts as is.

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Blue Hell
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Joined: Apr 03, 2004
Posts: 20536
Location: The Netherlands, Enschede
Audio files: 147
G2 patch files: 318

PostPosted: Thu May 02, 2013 1:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

http://www.programmersheaven.com/download/13383/6/ZipView.aspx may give some more hints.
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oneoff



Joined: Nov 23, 2008
Posts: 43

PostPosted: Fri May 03, 2013 5:28 am    Post subject: Reply with quote  Mark this post and the followings unread

I still have 2 pcs. UA726 NOS , the originals
Golden pins , they are still in a plastic wrap .
Please send a PM if you're interested.
Cheers
Oneoff
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soundforger



Joined: Jun 24, 2011
Posts: 20
Location: The Netherlands

PostPosted: Sun May 05, 2013 5:34 am    Post subject: Reply with quote  Mark this post and the followings unread

@ Blue Hell:

I'll check out some datasheets to see what I can use instead of the 741's.

Thanks for the link. Yes, I know this one. I read the blogs of Rick Jansen, Michel van Osenbruggen, Klaus Pohlig and Bruce Bates. And I have the books by Chapman and Aigner.

@ oneoff

Thanks for the offer! I just pmd you. The formant uses 1 ua726 per VCO and I want to build 4 or 5 of them. This would mean a great start, because I dont have to change the original schematic and pcb.

If anyone else wants to part from these parts, I would be more than happy to buy them!! Razz
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