4046 VCO experiment

[Hairy Harry]

Hi all...

The V/F chips can be very good (if you want linear...) but
most have price tags to match. I just checked out Analog Devices
(official business) and there were a lot of $30 V/F chips (@1000pcs)

err.... ouch ???

H^)  harry


>From: Jim Patchell <patchell at silcom.com>
>To: synth-diy at node12b53.a2000.nl
>Subject: Re: 4046 VCO experiment
>Date: Fri, 18 Aug 2000 08:10:00 -0700
>
>
>
>Scott Gravenhorst wrote:
>
> > Harry, Martin and all,
> >
> > Thanks for the help andsuggestions.  It seems that the 4046 VCO
> > really isn't suited for this sort of application.  It hasn't
> > performed in a linear fashion for me, at least not over a large
> > enough range to be a musical VCO.  Great little PLL though.
> >
> > I now have 3 options on the table:
> >
> > AD654, XR2206 and 566.
> >
> > I like the AD654 because it has a built in V/I converter.  The 566
> > can probably work with an external V/I converter.  Looking at XR2206,
> > I think it has one built in too.  Now I am determining how close to
> > "unobtainium" each of these is.  I've already had trouble ordering
> > the 566, I got my order bounced from 2 places for zero on hand, I
> > still have one order pending.
> >
>
>     A couple of days ago I posted a message that listed the linearities
>of selected (and ancient) VCO chips.  Even over 1 decade, the XR2206
>would not make a good musical VCO (I already forgot the number that I
>posted, but it was about 2% over 10:1, much worse over 1000:1, something
>like 5-8%).  I don't really understand why some of these oscialators are
>so bad.  And I can understand why one would want a single chip,
>inexpensive solution to a VCO (I really wish the CEM3340 was still in
>production).
>
>     The thing that amazed me was that the 8038 was the best of the lot
>(with a 0.2% linearity).
>
>     Has anybody tried the off the shelf V->F converters?  I seem to
>remember that some of these are down in the 0.01% linearity range.
>
> >
> > <sigh>
> >
> > If worse comes to worst, I may just clone the FatMan VCO.  At least
> > I can get the parts for it.
> >
> > -- Scott Gravenhorst : On The Edge, but the Edge of What?
> > -- Linux Rex, Linux Vobiscum  |  RedWebMail by RedStarWare
> > -- FatMan: www.teklab.com/~chordman
> > -- NonFatMan: members.xoom.com/_XMCM/chordman/index.html
> > -- The 21st century does NOT start in the year 2000!!!
>
>-Jim
>
>

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