[sdiy] Cheapest Matched Pair

[patchell]

    I can double that.  I made some dual VCO's from MAT-04's and had no problems with
soft syncing either.

harrybissell wrote:

> Hmmm... i wonder.
>
> I have never tried the 3046 for a dual VCO...
>
> but I have used the MAT-04 and had no soft syncing
> problems.  I used the pairs of 1,2,3 and 12,13,14 (iirc)
> for the two expo converters...
>
> and I paralleled the pair at 5,6,7 and 8,9,10 ... diode connected
> I hoped that this would give the best read of the chip temperature...
>
> It worked well.  Maybe the 3046 has some better and worse pairs
> to use in a dual...
>
> but hell, they're cheap so why not use two and not worry
>
> H^) harry
>
> Grant Richter wrote:
>
> > Merry Christmas to All,
> >
> > One other caution on the CA3046. If you use two sets of transistors
> > internally to make the expo converter for two VCOs. The VCOs will tend to
> > "soft synch" probably due to capacitive coupling in the CA3046.
> >
> > Using Rossum compensation (diode and resistor) you can make an expo VCO that
> > tracks +/- 5 cents or better over 8 octaves.
> >
> > >
> > > Joe, Oren etal --
> > >
> > > The CA3046 is indeed speced to 5 mV matching, but in practice it is usually
> > > much better due to improvements in Si technology in the years since the device
> > > originally came out.
> > >
> > > Also the beta is usually much better than speced.
> > >
> > > The main drawback of this array is the relatively high emitter series
> > > resistance.  This needs to be compensated for in critical converter
> > > applications.
> > >
> > > If you can find it, the CA3083 is quite a bit better than the CA3046 in this
> > > regard.
> > >
> > > Seasons greetings to all!
> > >

--
 -Jim
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