Quadrature VCO

[Jim Patchell]

KA4HJH wrote:

> >     Yes it is.  In the Nov/.Dec 1980 issue of Polyphony there is a circuit
> >that uses a single CA3280, but an LM13700 could be used instead.  Another
> >reference, if you don't have that one is page 80 in the Analog Devices
> >Non-linear circuits handbook (which is where the first circuit I mentioned
> >was derived).  If you don't have either, I can xerox off a copy and send
> >them to you.
>
> Jim, you humble SOB. I went to look at that and found out you wrote it!
>
> Still got any 3280's? How about the TD401?  8^)

    The TD401 was a matched (and that term is used loosely here, delta Vbe was
10mV) PNP transistor.  You can probably match a pair of 2n3906's a lot better
than that, or I would be willing to bet just picking two at random would probbly
be matched better than that.  The TD401 was convienent because it was a dual,
and wasn't very expensive.  Sprague, who made the TD401, put that part out to
pasutre a long time ago.  I do have the CA3280.  I got mine from Newark.  I am
also willing to sell mine.  I can't remember how much, off the top of my head,
but are listed on my web site http://www.silcom.com/~patchell.


>
>
> --
> Terry Bowman, KA4HJH
> "The Mac Doctor"

    -Jim