[sdiy] UAF42

[phillip m gallo]

Well according to TI it's still in production in DIP and SMD but now
that  Burr Brown is TI, the old fab is obsolete.  You can find it's
product page @:

http://focus.ti.com/docs/prod/folders/print/uaf42.html#inventory

The appnotes and the design software can be found there.  

The budgetary for 1k pcs is $7.55 US so the old Digikey markup rears
it's head again.    These chips conform to the standard "pricey" Burr
Brown marketing model.

Being that an SVF needs only two precision caps, a Mouser order for
poly's and a little handpicking is probably a better solution.  

regards,
p




-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Scott
Gravenhorst
Sent: Tuesday, February 24, 2004 2:53 PM
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] UAF42


I thought for a fixed cutoff filter bank, "why not?" until I did a
search.  I checked Jameco, Digikey and Mouser, only Digikey 
had it (around 1000 in stock) for $12.58 in unit quantities, no larger
quantity prices were listed.  Digikey notes that it is 
obsolete.  For _that_ much $, I think a  decent quad opamp and 
some good caps might be more economical.



Scott Stites <scottnoanh at peoplepc.com> wrote:
>Hi Scott,
>
>Good points, indeed. I have to agree with Phillip, though, for
>Vactrol hounds like me, it would make a pretty compact little SVF 
>(haven't calculated it yet, but I think the 1000 pF caps in that 
>case would be fine). Of course, the matching of the Vactrols 
>would obliterate the spec on the caps =-D. 
>
>An exponential current sink to drive the Vactrols would take a
>couple of transistors, and, while I'm at it, hang a Vactrol off 
>of pin 3 and get VC resonance. 
>
>Now that Rene Schmitz 4007 design......I'll definitely have to try 
>that, too!
>
>Cheers,
>Scott
>
>-----Original Message-----
>From: Scott Gravenhorst <music.maker at gte.net>
>Sent: Feb 24, 2004 12:37 PM
>To: synth-diy at dropmix.xs4all.nl
>Subject: Re: [sdiy] Cool chip alert
>
>Wow, I thought it was a wanked design as well.
>
>The other URLs pointing to clever usage of this were OK, but I think 
>there's something seriously wrong with using external OTAs to allow 
>voltage control of something like this.  The integrators on the chip 
>should have been made of OTAs, not opamps, IMHO.  That would have been 
>far more useful than what they did.  After all, a SVF - VOLTAGE 
>CONTROLLED, can be made out of a single dual OTA IC.  And if I want to 
>mess with unusual designs, I'll happily build the René Schmitz 4007 VC 
>state variable filter.  I fail to see anything superior about this IC 
>other than the matched 1000pf caps (which are too large IMHO and you're

>stuck with them).  And I think that there are ways we can match caps to

>make a better OTA based VC-SVF.
>
>Just my $.02 worth of pure opinion.
>
>
>
>
>
>
>
>
>
>
>
>Colin Hinz <asfi at eol.ca> wrote:
>>On Mon, 23 Feb 2004, Tim Escobedo wrote:
>>
>>> http://www.speakjet.com
>>>
>>> Might be useful for sone nice effects.
>>
>>Who are these people? And why did they let such a wanker design their 
>>website?
>>
>>Okay, I don't really expect an answer to the second question, though 
>>neither of their news items display anything except the headline. Oh 
>>well, I'm sure they've got a very good reason for doing it this way.
>>
>>The company's main website is much closer to being wank-free, luckily:
>>
>>http://www.magnevation.com/
>>
>>I do wonder what's in the guts of the SpeakJet -- it's not like a few 
>>guys working in an industrial park in Alabama can suddenly build a fab

>>to start churning out mixed-signal ASICs..........and as they're 
>>really clear about providing an entirely American-made product (and I 
>>don't have any problem with "buy domestic" campaigns, as we could use 
>>a bit of that up here), so that implies a fab in the USA.
>>
>>Looks like quite an interesting chip. If I thought there'd be any 
>>chance I'd get around to doing something with them in my lifetime, I'd

>>buy a few. But first I'd better build something permanent with my pair

>>of SN76477s......
>>
>>- Colin Hinz
>>  Toronto, Canada
>>
>>
>
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>-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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=========================================================  
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/FatMan/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.