matched expo source / sink idea

[Haible Juergen]

I remember in this Aries VCO with Triangle master and
SAW slave there was a special expo converter that was
not shown in the schemos (at least not in the copy I have).

When I build my own dual core VCO (yes, inspired by that
Aries circuit) I don't remember what kind of expo converters I
used. 

But lately I was thinking of an easy solution. I've drawn a little
circuit that should work with a 3096, but it's UNTESTED.
Simulation results are good, so I've put it on the web for
discussion:

http://home.debitel.net/user/jhaible/jh_expo_source_sink.gif

Comments and critical feedback welcome.

JH.