build your own tempco resistors ??

[Haible_Juergen#Tel2743]

Hi!

I just took a first glance on the Transcendent 2000 at Anders Sponton's 
page.

http://www.tellus.vallentuna.se/gymninfo/personal/anders/andersus.html

 There are two iteresting things about
expo converters in VCOs:

(1) A different expo converter topology! Instead of the usual
differential pair with a current regulation loop around the
transistor that serves as a reference, they keep the
current constant by *separating* the pair with a voltage
buffer! The idea looks nice; are there any drawbacks?

(2) The tempco resistor is interesting. They write that copper
has approximately the right tempco - now can we wind our
own tempco resistors with thin copper wire? (Drilling
machine; first half of windings one direction, second half
reverse direction, to get low L ...)
What do you think?

JH.