[sdiy] Fw: Reference stabilizes exponential current

[harry bissell]

BILL TRAVIS circuit ???

This is a problem. The circuit was by Tom Napier,
North Wales, PA.

Bill Travis (while a good enough guy) is an
EDITOR at EDN, not the designer.

I did not see the online version but if you did...
and it attributes this design idea to Bill Travis...

PLEASE contact EDN immediatly and request they publish
a correction (because its wrong) and an APOLOGY...

because this is not the first time they've done this.
I have contected them in the past. They should KNOW by
now...

H^(  harry   (un-Happy)




--- Jim Patchell <patchell at silcom.com> wrote:
>     What he did is not all that different from
> experments that I have done, as
> well as JH did.  The output of IC3 is proportional
> to temperature, and can be
> used to control the gain of the expo driver.  The
> methodes that JH and myself
> use don't require an extra transistor in expo array
> so that they could be used
> with just matched pairs.  However, I have to say, if
> you are going to be using a
> DAC to set the pitch of your VCO, the Bill Travis
> circuit does have a certain
> apeal.
> 
> Craig Critchley wrote:
> 
> > The author of this article must be a nut for
> different ways to build an
> > exponential converter.  I thought the name looked
> familiar from a recent
> > Circuit Cellar article, from the September issue,
> and sure enough the name's
> > the same.
> >
> > In the Circuit Cellar article, he uses two
> additional transistors in a
> > ca3046 to heat the chip to a constant temperature.
>  In that article it was
> > driving a 74hct4046 vco.  He claimed 4 decades of
> accuracy for it.
> >
> > It doesn't look like this article is online yet,
> but the Circuit Cellar
> > archive only goes up to Aug. so maybe it will be
> available later.
> >
> >                             ...Craig
> >
> > ----- Original Message -----
> > From: "Michael Lloyd" <mlloyd1 at enteract.com>
> > To: <synth-diy at dropmix.xs4all.nl>
> > Sent: Wednesday, October 31, 2001 6:20 PM
> > Subject: [sdiy] Fw: Reference stabilizes
> exponential current
> >
> > ----- Original Message -----
> > From: Michael Lloyd
> > To: mlloyd
> > Sent: Wednesday, October 31, 2001 2:59 PM
> > Subject: Reference stabilizes exponential current
> >
> >
>
http://www.e-insite.net/ednmag/index.asp?layout=article&stt=000&articleid=CA
> > 178103&pubdate=10/25/2001
> 
> 
> 


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