[sdiy] korg ms02 antilog amp and log amp

[René Schmitz]

Hi Ian and all,

> Ah, yes, now I remember you did those.  The pair I measured was actually 
> an NTE42, whatever that really is.  :-)

Yes, some years ago I asked about a Rbe measuring technique, and you 
came up with some measurements and the method from a GE manual.

> IIRC, the CA3083 is even less expensive than the Japanese pairs, and you 
> can use one of the free transistors to make the diode for the hf 
> tracking circuit.

That is nice, of course. The price is way lower here too.
I had thought about using the CA3083 for quite some time, and I would 
try to parallel the transistors to maybe reduce the Rbe, and possibly 
getting a poor mans version of common centroid layout. (But for that it 
would be nice to have a picture of the metallisation mask for the 
CA3083) Do you have made any tests how well the other transistors match 
to the matched pair transistors?

The only thing that bothers me is the size of the package, its rather 
huge compared to the japanese duals. Also coupling the PTC element to 
the chip is somewhat more cumbersome than with the japanese pairs. (I 
use the KTY81, which comes in a TO92 case and can be conveniently glued 
face to face on the 2SC types, whereas the leads are to short to have it 
glued to the DIP size cases.)

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159