[sdiy] uA726 transistor array

[harrybissell]

Hmmm...

You CAN parallel the transistors in the MAT-04.   I built a hack
of TomG's VCO3 that was set up for the CA3046.  I wanted the
better transistors of the MAT-04... but that design uses one tranny
as a diode (with op-amp) to set the operating point for a single
transistor VCO.  So the design used three trannies... and I had four.
Because they are pairs... I worried about thermal effects... one tranny
would be closer to the expo of OSC1 than OSC2... so I paralleled the
diode trannies...figuring I'd get a better approximation.

It worked well... but hey it don't answer your question Rene, does it ?
Anyway its worth a try...

Makes you think you might cross connect the MAT-04 trannies as well
for greater thermal stability.  (after the MAT-01, 02 samples run out ;^)

H^) harry

René Schmitz wrote:

> Hi everyone!
>
> >Jörgen Bergfors reported to me in a private email-session that he noted that
> >the LM311 comparator where a source of thermally induced frequency shift. This
> >is logical since the comparator is used to detect the phase-ramp against some
> >stable level. The comparator core is another diffrential transistor-pair, so
> >we should not be supprised.
>
> Can someone quantify this effect? (The last few hundred ppm are the hardest ;-)
>
> IMO having two comparators and thresholds (i.e. precision schmitt trigger)
> is better anyway, the drift will cancel.
>
> >I've been thinking about MAT-04's too. What I really would like to see is a
> >MAT-02 (which is a MAT-04 but with pair-wise wireing of transistors to better
> >handle temperature gradients, a chip-trick being a bit hard to do otherwise)
> >but with a handfull of extra transistors so that a distributed heater and
> >multiple senses can be applied.
>
> Hmm, and just two hours ago I wondered if one could parallel the transistors in
> a MAT04 to get lower rBE....
>
> Cheers,
>  René
>
> --
> uzs159 at uni-bonn.de
> http://www.uni-bonn.de/~uzs159
>
>